Chapter 15 The Urinary System

Cortex

Most nephrons are located within the renal ___.

Nephron

The functional unit of the kidney that filters blood and forms urine is the _____.

Glomerulus

Knot of capillaries in the renal corpuscle

Hydrogen ions/bicarbonate ions

How does the urinary system respond to blood that has become acidic? -Both secrete more _______ and reabsorb more ____________

Filtered but poorly reabsorbed

Nitrogenous waste products, such as urea and uric acid, are _____.

bicarbonate; hydrogen

The kidneys help maintain a rising blood pH by excreting _____ ions and reabsorbing ____ ions by the tubule cells.

Intracellular fluid

What is the largest fluid compartment in the body?

urea

Which of the following is NOT a substance typically reabsorbed by the tubules under normal healthy conditions? -urea -sodium -glucose -amino acids -water

Transitional

The urinary bladder is able to expand as urine accumulates within it due to the presence of ______ epithelium.

Reduce water content of urine

What is the main effect of ADH?

99%

The percentage of filtrate eventually reabsorbed into the bloodstream is closest to:

Renal pyramids

The triangular regions of the kidneys that are striped in appearance and separated by the renal columns are the _____.

1500 mL/day

The average output of urine for a normal healthy adult is:

Strong acids

What chemical dissociates completely and liberates all the hydrogen ions when dissolved in water?

Ureter

The tube connecting the renal hilum of the kidney to the bladder is the ____.

Glucose

Aldosterone does NOT directly or indirectly regulate _____.

Proximal convoluted tubule (PCT)

The portion of the renal tubule closest to the glomerulus is the ______.

External urethral sphincter

The voluntarily controlled sphincter fashioned by skeletal muscle at the point where the urethra passes through the pelvic floor is called the ____.

Glomerular capsule

Filtrate formed during glomerular filtration is captured by the ______.

Produce hormones that assist in digestion

Which one of the following is NOT one of the functions of the kidneys? -convert vitamin D from its inactive to its active form -regulate blood volume -manufacture urine -dispose of metabolic waste products -produce hormones that assist in digestion

Depressed

When blood pH begins to rise, the respiratory control centers in the brain are ______.

reduce water content of urine

What is the main effect of ADH?

It causes sodium to be reabsorbed and potassium excreted.

What is the mechanism of aldosterone?

glucose

Which of these is not found in normal urine? potassium urea sodium glucose

bicarbonate; hydrogen

The kidneys can help maintain a rising blood pH by excreting ________ ions and reabsorbing ________ ions by the tubule cells.

afferent arteriole

The blood vessel directly feeding the glomerulus with blood from the cortical radiate artery is the ________.

creatinine

Which one of the following substances is normally found in urine?

11th and 12th ribs

What bones provide some protection for the kidneys?

glomerular capsule

Which part of the nephron is involved in filtration?

glomerulus

Of the capillary beds associated with each nephron, the one that is both fed and drained by arterioles is the:

renal (medullary) pyramids

The triangular regions of the kidneys that are striped in appearance and separated by the renal columns are the ________.

bicarbonate buffer system

The chemical buffer system that includes carbonic acid and its salt, which ties up the H+ released by strong acids, is called the:

blood proteins

Filtrate typically does NOT contain:

normal

A blood pH of 7.4 is considered:

renal pelvis

To what part of the kidney does the ureter attach?

pigment normally found in urine

What is urochrome?

retroperitoneal

Which one of the following terms describes the location of the kidneys:

hydrogen ions

Buffers prevent dramatic changes in concentrations of ______.

tubular reabsorption

Aldosterone promotes sodium and thus water to move from the filtrate through the tubule cells into the blood

efferent arteriole

Items in the blood that are NOT filtered will travel from the glomerulus to the ________.

Tubular Secretion

Unneeded substances such as potassium, urea, and creatinine are moved from the blood of the peritubular capillaries into the filtrate

Glomerular filtration

Water and solutes are forced from the blood into the glomerular capsule of the nephron

It causes kidney-collecting ducts to reabsorb more water.

What is the primary action of antidiuretic hormone?

cortical radiate veins, arcuate veins, interlobar veins, renal vein

As venous blood is drained from the kidney, which path does it follow:

proximal convoluted tubule

Which part of the nephron receives fluid from the glomerular capsular space?

Filtrate formed by the glomerular capillaries is captured by a portion of the renal tubule (shown at the arrow designated A) known as the ______.

glomerular (Bowman’s) capsule

What renal process occurs at the glomerular capillaries of the nephron?

glomerular filtration

Which tube is the passageway for urine as it travels from each kidney to the bladder?

ureter

What bones provide some protection for the kidneys?

11th and 12th ribs

Which of these is found in the medulla of a kidney?

renal pyramid

What part of a nephron connects to both the proximal and the distal convoluted tubules?

loop of henle

Which of these is a nitrogenous waste produced by the liver and poorly reabsorbed by the kidney?

urea

What is the source of the usual color of pigment in urine?

hemoglobin breakdown

Which of these is not found in normal urine?

glucose

To what part of the kidney does the ureter attach?

renal pelvis

What part of a nephron is responsible for absorbing just water and salt?

loop of henle

Which of these is a nitrogenous waste associated with muscle tissue?

creatinine

What is urochrome?

a pigment normally found in urine

What part of the urinary bladder is bounded by the orifices of the ureter and urethra?

trigone

What happens when the external urethral sphincter is voluntarily relaxed at the same time that the pelvic splanchnic nerves are active?

micturition

What causes the opening of the internal urethral sphincter?

pressure from the contracting bladder

What is the area in the urinary bladder that is bordered by the three orifices of the bladder?

trigone

Which of these must be inhibited for micturition to occur?

contraction of these must be inhibited for micturition to occur

Where is the majority of water located in the human body?

intracellular fluid (ICF)

When hypothalamic osmoreceptors become more active as blood plasma solute levels increase, what hormone is released?

antidiuretic hormone (ADH)

Which hormone regulates the sodium ion content of the ECF to assist with the regulation of water balance?

aldosterone

What is the main effect of ADH?

reduce water content of urine

What substance’s urinary reabsorption is influenced by aldosterone?

sodium

calyx

a cup of flowers (minor calyx)

detrudere

to push down (detrusor muscle)

fenestra

a window (fenestrated capillaries)

glomus

a ball (glomerulus)

gonion

angle (trigone)

juxta

near (juxtaglomerular apparatus)

micturire

to urinate (micturation)

nephros

kidney (nephron)

papillae

small, nipple-shaped projections (renal papillae)

[pdpm

fppt (podocyte)

rectus

straight (vasa recta)

ren

kidney (renal artery)

retro-

behind (retroperitoneal)

vasa

vessels (vasa recta)

5 Functions of the Urinary System

Elimate organic wastes; Regulate blood volume & blood pressure (adjust water loss; release cardiovascular hormones); Regulate plasma ion levels; Stabilize blood pH; Conserve nutrients.

3 ways Urinary System regulates
blood volume & pressure

(1) adjusting the volume of water lost in the urine, (2) releasing erythropoietin, (3) releasing renin.

Regulation of plasm ion levels by the Urinary System

The plasma concentrations of sodium, potassium, chloride, & other ions are regulated by controlling the quantities lost in the urine, & the plasma concentration of calcium ions is regulated by the synthesis of calcitriol.

How the Urinary System stabilizes blood pH

Blood pH is stabilized by controlling the loss of hydrogen ions (H+) & bicarbonate ions (HCO3) in the urine.

How the Urinary System conserves nutrients

Nutrients such as glucose & amino acids are conserved by preventing their excretion in the urine while organic waste products (especially the nitrogenous wastes urea & uric acid) are eliminated.

Components of the Urinary System

Kidneys (produce urine, a fluid made of water, ions, soluble compounds); Ureters; Urinary bladder; Urethra.

Structural Features of the Kidneys

The kidneys are located on either side of the vertebral column between the last thoracic & third lumbar vertebrae. The right kidney often sits slightly lower than the left, & both lie between the muscles of the dorsal body wall & the peritoneal lining. This position is called retroperitoneal (retro-, behind) because the organs are behind the peritoneum. The position of the kidneys is maintained by the overlying peritoneum, contact with adjacent organs, and supporting connective tissues. Each kidney is covered by a dense, fibrous renal capsule and is packed in a soft cushion of adipose tissue. The renal capsule covers the surface of the kidney & lines the renal sinus, an internal cavity. An indentation called the hilum is the site of exit for the ureter, as well as the site at which the renal artery & renal nerve enter & the renal vein exits. A typical kidney is reddish-brown & about 10 cm (4 in.) long, 5.5 cm (2.2 in.) wide, & 3 cm (1.2 in.) thick in adults. Each kidney weighs about 150 g (5.25 oz).

Internal Anatomy of the Kidney

Urine production occurs in the renal pyramids & overlying areas of renal cortex. Ducts within each renal papilla discharge urine into a cup-shaped drain, called a minor calyx (calyx, a cup of flowers; plural calyces). Four or five minor calyces merge to form the major calyces, both of which combine to form a large, funnel-shaped chamber, the renal pelvis. The renal pelvis is connected to the ureter, through which urine drains out of the kidney.

What is the Renal Cortex?

The outer layer (enclosed/covered by the renal capsule).

What is the Renal Medulla?

The inner layer, containing 6 t 18 conical renal pyramids. The tip of each pyramid, known as the renal papilla, projects into the renal sinus. Bands of cortical tissue called renal columns extend toward the renal sinus between adjacent renal pyramids.

Difference between the Renal Hilum & the Renal Pelvis?

The hilum is the convergence of all the veins, arteries, & nerves entering the organ while the pelvis is the convergence of the major calyxes in the kidney.

In which part of the kidneys does urine production occur?

Urine production occurs in the renal pyramids & overlying areas of renal cortex. Ducts within each renal papilla discharge urine into a cup-shaped drain, called a minor calyx (calyx, a cup of flowers; plural calyces). Four or five minor calyces merge to form the major calyces, both of which combine to form a large, funnel-shaped chamber, the renal pelvis. The renal pelvis is connected to the ureter, through which urine drains out of the kidney.

Nephrons

Urine production begins in the renal cortex, in microscopic tubular structures called nephrons . Each kidney has roughly 1.25 million nephrons.

Flow of blood through a kidney

Each kidney receives blood from a renal artery that originates from the abdominal aorta. As the RENAL ARTERY enters the renal sinus, it divides into branches that supply a series of INTERLOBAR ARTERIES that radiate outward between the renal pyramids. They then turn, arching along the boundary lines between the cortex & medulla as the ARCUATE ARTERIES. Each arcuate artery gives rise to a number of INTERLOBULAR ARTERIES supplying the cortex. Afferent arterioles branching from each interlobular artery deliver blood to the capillaries supplying individual nephrons.

Breakdown of Renal Blood Supply (arterial)

RENAL ARTERY; INTERLOBAR arteries (radiate out between renal pyramids); ARCUATE arteries (arching along the boundary lines between the cortex & medulla); INTERLOBULAR arteries (arcuate arteries give rise to interlobular arteries, which supply the renal cortex).

Afferent arterioles

Afferent arterioles branch from each interlobular artery & deliver blood to the capillaries supplying individual nephrons.

Amount of blood flowing through the Kidneys each minute (and percentage of cardiac output)

About 1200ml of blood flows through the kidneys each minute, or some 20-25 percent of the cardiac output.

Nephron Level of Blood Supply

Blood reaches each nephron through an afferent arteriole & leaves in an efferent arteriole. It then travels to the PERITUBULAR CAPILLARIES that surround the proximal & distal convoluted tubules (PCT & DCT). The peritubular capillaries provide a route for the pickup or delivery of substances that are reabsorbed or secreted by these portions of the nephron. In juxtamedullary nephrons (juxta, near), which are located near the renal medulla, the peritubular capillaries are connected to the VASA RECTUS (rectus, straight)—long, straight capillaries that parallel the loop of Henle deep into the medulla . It is the juxtamedullary nephrons that enable the kidneys to produce concentrated urine. lood from the peritubular capillaries and vasa recta enters a network of venules and small veins that converge on the INTERLOBULAR VEINS. In a mirror image of the arterial distribution, blood continues to converge & empty into the ARCUATE, INTERLOBAR, & RENAL VEINS.

Structure & Overview of a Nephron

The nephron begins at the RENAL CORPUSCLE, a round structure consisting of a cup-shaped chamber (called Bowman’s capsule) that contains a capillary network, or GLOMERULUS. Blood arrives at the glomerulus by way of an afferent arteriole & departs in an efferent arteriole. In the renal corpuscle, blood pressure forces fluid & dissolved solutes out of the glomerular capillaries & into the surrounding capsular space. This process is called ‘filtration’. Filtration produces a protein-free solution known as ‘filtrate’. From the renal corpuscle, the filtrate enters the renal tubule. The major segments of the renal tubule are the Proximal Convoluted Tubule (PCT), the loop of Henle, & the Distal Convoluted Tubule (DCT). As filtrate travels along the tubule, its composition gradually changes, & it is then called ‘tubular fluid’. The changes that occur & the urine that results depend on the specialized activities under way in each segment of the nephron. Each nephron empties into a ‘collecting duct’, the start of the ‘collecting system’. The ‘collecting duct’ leaves the cortex & descends into the medulla, carrying ‘tubular fluid’ from many nephrons toward a ‘papillary duct’ that delivers the fluid, now called URINE, into the calyces & no to the renal pelvis….

Which part of the nephron does filtration occur?

Renal corpuscle

How does the Bowman’s capsule relate to the Glomerulus?

The renal corpuscle consists of (1) the capillary network of the glomerulus, & (2) a structure known as the Bowman’s capsule, which forms the outer wall of the renal corpuscle & encapsulates the glomerular capillaries. Inbetween the ‘capsular epithelium’ lining the inside of the Bowman’s capsule, & the ‘specialized epithelium’ covering the glomerular capillaries is the ‘capsular space’. Filtrate is squeezed from the glomerulus into the capsular space, where it begins its journey through the PCT, loop of Henle, & DCT…

The Process of Filtration

The ‘specialized epithelium’ covering the glomerular capillaries consists of cells called podocytes. Podocytes have long cellular processes called pedicels that wrap around individual capillaries. A thick basement membrane sperates the ‘specialized endothelial cells’ of the capillaries from the podocytes. The glomerular capillaries are said to be ‘fenestrated’ – because their ‘specialized endothelial cells’ contain pores. To enter the capsular space (to become ‘flitrate’), a solute must be small enough to pass through (1) the pores of the specialized endothelial cells, (2) the fibers of the basement membrane, & (3) the filtration slits between the slender processes of the podocytes. The fenestrated capillary, basement membrane, & filtration slits form a ‘filtration membrane’ that prevents the passage of blood cells & most plasma proteins but permits the movement of water, metabolic wastes, ions, glucose, fatty acids, amino acids, vitamins, & other solutes into the capsular space. Most of the valuable solutes will be reabsorbed by the proximal convoluted tubule (PCT).

Flow of Filtrate through a Nephron to a Calycate

From the renal corpuscle, the filtrate enters the renal tubule. The major segments of the renal tubule are the proximal convoluted tubule (PCT), the loop of Henle, & the distal convoluted tubule (DCT). As the filtrate travels along the tubule, its composition gradually changes, & it is then called tubular fluid. The changes that occur and the urine that results depend on the specialized activities under way in each segment of the nephron. Each nephron empties into a collecting duct, the start of the collecting system. The collecting duct leaves the cortex & descends into the medulla, carrying tubular fluid from many nephrons toward a papillary duct that delivers the fluid, now called urine, into the calyces & on to the renal pelvis.

Functions of the Kidneys

Remove waste products from blood; Assist in regulation of blood volume & blood pressure, ion levels, & blood pH.

Functions of Renal Tubule

Reabsorbing all of the useful organic molecules from the filtrate; Reabsorbing over 90% of the water in the filtrate; Secreting into the tubular fluid any waste products that were missed by the filtration process.

Functions of the Nephron

Production of filtrate (Glomerulus); Reabsorption of nutrients (PCT); Reabsorption of water & ions (DCT, collecting duct).

Proximal Convoluted Tubule (PCT)

Filtrate moves into the first segment of the renal tubule, the proximal convoluted tubule (PCT). The cells lining the PCT absorb organic nutrients, plasma proteins, & ions from the tubular fluid & release them into the interstitial fluid surrounding the renal tubule where this reabsorbed fluid enters the peritubular capillaries. As a result of this transport, the solute concentration of the interstitial fluid increases while that of the tubular fluid decreases. Water then moves out of the tubular fluid by osmosis, reducing the volume of tubular fluid.

Transport of reabsorbed substances from filtrate in PCT back to bloodstream:

Reabsorbs critical substances from filtrate (ions, proteins, & nutrients like glucose & amino acids); Releases them into surrounding interstitial fluid; Enter peritubular capillaries & return to bloodstream.

Loop of Henle

This loop is composed of a descending limb that travels toward the renal pelvis & an ascending limb that returns to the cortex. The ASCENDING LIMB, which is NOT PERMEABLE TO WATER & SOLUTES, actively transports sodium & chloride ions out of the tubular fluid. As a result, the interstitial fluid of the medulla contains an unusually high solute concentration. The DESCENDING LIMB IS PERMEABLE TO WATER, & as it descends into the medulla, water moves out of the tubular fluid by osmosis.

Distal Convoluted Tubule (DCT)

The ascending limb of the loop of Henle ends where it bends & comes in close contact with the glomerulus & its vessels. At this point, the distal convoluted tubule (DCT) begins, & it passes immediately adjacent to the afferent & efferent arterioles. The DCT is an important site for the active SECRETION of ions, acids, drugs, & toxins & the selective reabsorption of sodium ions from the tubular fluid. In the final portions of the DCT, an osmotic flow of water assists in concentrating the tubular fluid. The epithelial cells of the DCT closest to the glomerulus are unusually tall, & their nuclei are clustered together. This region of the DCT is called the macula densa. The cells of the macula densa are closely associated with unusual smooth muscle fibers – the juxtaglomerular (juxta, near) cells – in the wall of the afferent arteriole. Together, the macula densa & juxtaglomerular cells form the juxtaglomerular apparatus, an endocrine structure that secretes the hormone erythropoietin and enzyme renin.

Juxtaglomerular Apparatus

The juxtaglomerular apparatus is a microscopic structure in the kidney, which regulates the function of each nephron. The juxtaglomerular apparatus is named for its proximity to the glomerulus: it is found between the vascular pole of the renal corpuscle & the returning Distal Convoluted Tubule (DCT) of the same nephron. This location is critical to its function in regulating renal blood flow & glomerular filtration rate. The three cellular components of the apparatus are the macula densa of the distal convoluted tubule, smooth muscle cells of the afferent arteriole and juxtaglomerular cells. The juxtaglomerular apparatus secretes the hormone erythropoietin & the enzyme renin.

Erythropoietin

EPO secretion is stimulated by low O2 concentration in the blood. EPO stimulates erythrocyte production in the red marrow. EPO also increases blood volume, & consequently blood pressure.

Renin

The enzyme renin is released by kidney cells in response to a decline in blood volume, blood pressure, or both. Once in the bloodstream, renin starts an enzymatic chain reaction known as the renin-angiotensin system, that leads to the formation of the hormone angiotensin II. Renin carries out the conversion of angiotensinogen in the liver to angiotensin I. Angiotensin I is subsequently converted to angiotensin II by ‘angiotensin converting enzyme’ found in the lungs. Angiotensin II is a potent vaso-active peptide that causes blood vessels to constrict, resulting in increased blood pressure. Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the tubules of the kidneys to increase the reabsorption of sodium and water into the blood. This increases the volume of fluid in the body, which also increases blood pressure.

The Collecting System /
The Collecting Ducts

The distal convoluted tubule, the last segment of the nephron, opens into the collecting system. The collecting system consists of collecting ducts & papillary ducts. Each collecting duct receives tubular fluid from many nephrons, & several collecting ducts merge to form a papillary duct, which delivers urine to a minor calyx. In addition to transporting tubular fluid from the nephron to the renal pelvis, the collecting system can make final adjustments to the composition of the urine by reabsorbing water & by reabsorbing or secreting sodium, potassium, hydrogen, & bicarbonate ions.

Basic Overview of Collecting Ducts

Receive urine from nephrons; Merge into papillary ducts (delivers urine to minor calyx); Adjust final osmotic pressure of urine (by reabsorbing water & by transporting ions).

Cortical nephrons vs Juxtamedullary nephrons

Classified according to the length of their associated Loop of Henle & location of their renal corpuscle. All nephrons have their renal corpuscles in the cortex. Cortical nephrons have their Loop of Henle in the renal medulla near its junction with the renal cortex, while the Loop of Henle of juxtamedullary nephrons is located deep in the renal medulla; they are called juxtamedullary because their renal corpuscle is located near the medulla (but still in the cortex). The majority of nephrons are cortical. Cortical nephrons have a shorter loop of Henle compared to juxtamedullary nephrons. The longer loop of Henle in juxtamedullary nephrons create a hyperosmolar gradient that allows for the creation of concentrated urine. The path of blood from the peritubular capillaries differs in cortical & juxtamedullary nephrons: In juxtamedullary nephrons, the peritubular capillaries are connected to the vasa recta. It is the juxtamedullary nephrons that enable the kidneys to produce concentrated urine.

Overview of the Nephron & Collection System

Renal corpuscle – filtration of plasma to initiate urine formation; Proximal Convoluted Tubule (PCT) – reabsorption of ions, organic molecules, vitamins, water; Loop of Henle – Descending limb: reabsorption of water from tubular fluid / Ascending limb: reapsorption of ions; creates the concentration gradient in the medulla, enabling the kidney to produce concentrated urine; Distal Convoluted Tubule (DCT) – reabsorption of sodium ions; secretion of acids, ammonia, drugs; Collecting Duct – reabsorption of water & of sodium & bicarbonate ions; Papillary Duct – conduction of urine to minor calyx.

3 nitrogenous wastes the kidney excretes:

urea, creatinine, & uric acid

Urea

Urea is the most abundant organic waste. You generate about 21 grams of urea each day, most of it during the breakdown of amino acids.

Creatinine

Creatinine is generated in skeletal muscle tissue through the breakdown of creatine phosphate, a high energy compound that plays an important role in muscle contraction. Your body generates roughly 1.8 g of creatinine each day.

Uric acid

Uric acid is produced during the breakdown and recycling of RNA. You generate about 480 mg of uric acid each day.

Why is it important for the kidneys to be able to produce ‘concentrated’ urine?

Waste products (urea, creatinine, & uric acid) must be excreted in solution, & their elimination is accompanied by an unavoidable water loss. The kidneys can minimize this water loss by producing urine that is four to five times more concentrated than normal body fluids. If the kidneys could not concentrate the filtrate produced by glomerular filtration, water losses would lead to fatal dehydration within hours.

3 processes in urine formation

filtration, reabsorption, secretion

filtration

In filtration, blood PRESSURE forces water across the filtration membrane in the renal corpuscle. Solute molecules small enough to pass through the membrane are carried into the filtrate by the surrounding water molecules. Filtration occurs exclusively in the renal corpuscle, across the capillary walls of the glomerulus

reabsorption

Reabsorption is the removal of water & solute molecules from the filtrate & their reentry into the circulation at the peritubular capillaries. Reabsorption occurs after the filtrate enters the renal tubule. Whereas filtration occurs solely on the basis of size, reabsorption of solutes is a selective process involving simple DIFFUSION or the activity of carrier proteins in the tubular epithelium. Water reabsorption occurs passively through OSMOSIS. Reabsorption of nutrients occurs primarily at the proximal convoluted tubule (PCT).

secretion

Secretion is the transport of solutes out of the peritubular capillaries, across the tubular epithelium, and into the filtrate. This process is necessary because filtration does not force all of the dissolved materials out of the blood. Secretion can further lower the plasma concentration of undesirable materials, including many drugs. Active secretion occurs primarily at the distal convoluted tubule (DCT).

Where does regulation of the amount of water, sodium ions, & potassium ions lost in the urine occur?

Results from interactions between the loop of Henle & the collecting system.

Glomelular Filtration

Because the efferent arteriole has a high flow resistance, the blood hydrostatic pressure is much higher. The capsular pressure (interstitial pressure) is higher as well, but the net filtration pressure is much higher than in most tissue capillaries. The higher pressure, coupled with high solute & water permeability & large surface area, leads to an extraordinary flow of filtrate into Bowman’s capsule (125 mL/minute!). Blood pressure at the glomerulus forces water & solutes out of the bloodstream & into the capsular space. For filtration to occur, this outward force must exceed any opposing pressures, such as the osmotic pressure of the blood. The net force promoting filtration is called the filtration pressure. Filtration pressure at the glomerulus is higher than capillary blood pressure elsewhere in the body because of the slight difference in the diameters of afferent & efferent arterioles. The diameter of the efferent arteriole is slightly smaller, so it offers more resistance to blood flow than does the afferent arteriole. As a result, blood "backs up" in the afferent arteriole, increasing the blood pressure in the glomerular capillaries.

Glomerular Filtration Rate (GFR)

The glomerular filtration rate (GFR) is the amount of filtrate produced in the kidneys each minute. Because each kidney contains about 6 square meters of filtration surface, the GFR averages an astounding 125 ml per minute. This means that almost 20 percent of the fluid delivered to the kidneys by the renal arteries leaves the bloodstream & enters the capsular spaces. In the course of a single day, the glomeruli generate about 180 liters (50 gal) of filtrate, roughly 70 times the total plasma volume. But as the filtrate passes through the renal tubules, over 99 percent of it is reabsorbed.

Blood Pressure & GFR

Filtration pressure is very low (around 10mmHg), & kidney filtration will stop if glomerular blood pressure falls significantly. Reflexive changes in the diameters of the afferent arterioles, the efferent arterioles, and/or the glomerular capillaries can compensate for minor variations in blood pressure. These changes can occur automatically or in response to sympathetic stimulation. More serious declines in systemic blood pressure can reduce or even stop glomerular filtration. As a result, hemorrhaging, shock, or dehydration can cause a dangerous or even fatal reduction in kidney function. Because the kidneys are more sensitive to blood pressure than are other organs, it is not surprising to find that they control many of the hemostatic mechanisms responsible for regulating blood pressure & blood volume.

Proximal Convoluted Tubule (PCT) & Reabsorption

The cuboidal cells of the PCT have apical microvilli that increase luminal surface area & enhance reabsorption. These cells actively reabsorb nutrients, plasma proteins, & ions from the filtrate. The PCT returns about 70 percent of the filtrate to the peritubular capillary network, from where it returns to the circulation in the renal vein. Osmotic forces pull water across the wall of the PCT and into the surrounding interstitial fluid. The reabsorbed materials & water diffuse into peritubular capillaries. The PCT also actively reabsorbs ions, including sodium, potassium, calcium, magnesium, bicarbonate, phosphate, & sulfate ions. The ion pumps involved are individually regulated & may be influenced by circulating ion or hormone levels. For example, the presence of parathyroid hormone stimulates calcium ion reabsorption. Although reabsorption represents the primary function of the PCT, a few substances (such as hydrogen ions) can be actively secreted into the tubular fluid. Such active secretion can play an important role in the regulation of blood pH. A few compounds in the tubular fluid, including urea & uric acid, are ignored by the PCT & by other segments of the renal tubule. As water & other nutrients are removed, the concentrations of these waste products gradually rise in the tubular fluid.

Overview of Loop of Henle

The loop of Henle reabsorbs about half the water & two-thirds of the NaCl that remains in the tubular fluid. The descending limb reabsorbs water from the filtrate while the ascending limb pumps sodium & chloride ions from the filtrate into the interstitial space. This difference in transport between the two limbs establishes the hypertonic solute concentration in the interstitial space near the papilla needed to produce hypertonic urine. The ascending limb actively pumps sodium & chloride ions out of the tubular fluid & into the interstitial fluid of the renal medulla. Over time, a concentration gradient is created in the medulla; the highest concentration of solutes (roughly four times that of plasma) occurs near the bend in the loop of Henle. Because the descending limb is freely permeable to water, as tubular fluid flows along that limb, water continually flows out of the tubular fluid & into the interstitial fluid by osmosis. Roughly half the volume of filtrate that enters the loop of Henle is reabsorbed in the descending limb, & most of the sodium & chloride ions are removed in the ascending limb, leaving relatively highly concentrated waste products behind.

ADH, Aldosterone & Reabsorption

The DCT & collecting ducts contain ion pumps that respond to the hormone aldosterone produced by the adrenal cortex. Aldosterone secretion occurs in response to lowered sodium ion concentrations or elevated potassium ion concentrations in the blood. The higher the aldosterone levels, the more sodium ions are reclaimed, & the more potassium ions are lost. If circulating ADH levels are low, little water reabsorption will occur, & virtually all of the water reaching the DCT will be lost in the urine. If circulating ADH levels are high, the DCT and collecting duct will be very permeable to water. In this case, the individual will produce a small quantity of urine with a solute concentration four to five times that of extracellular fluids.

6 Steps of Kidney Function & Urine Production:

Step 1: Glomerular filtration produces a filtrate resembling blood plasma but containing few plasma proteins. This filtrate has the same osmotic, or solute, concentration as plasma or interstitial fluid. Step 2: In the proximal convoluted tubule (PCT), 60-70% of the water & almost all of the dissolved nutrients are reabsorbed. The osmotic concentration of the tubular fluid remains unchanged. Step 3: In the PCT & descending limb of the loop of Henle, water moves into the surrounding interstitial fluid, leaving a small fluid volume (roughly 20 percent of the original filtrate) of highly concentrated tubular fluid. Step 4: The ascending limb is impermeable to water & solutes. The tubular cells actively pump sodium & chloride ions out of the tubular fluid. Because only sodium & chloride ions are removed, urea now accounts for a greater proportion of the solutes in the tubular fluid. Step 5: The final composition & concentration of the tubular fluid are determined by events under way in the DCT & the collecting ducts. These segments are impermeable to solutes, but ions may be actively transported into or out of the filtrate under the control of hormones such as aldosterone. Step 6: The concentration of urine is controlled by variations in the water permeability of the DCT & the collecting ducts. These segments are impermeable to water unless exposed to antidiuretic hormone (ADH). In the absence of ADH, no water reabsorption occurs, & the individual produces a large volume of dilute urine. At high concentrations of ADH, the collecting ducts become freely permeable to water, 7 the individual produces a small volume of highly concentrated urine.

Disease in which kidneys do not process waste products effectively, characterized by proteinuria

Glomerulonephritis, the basement membrane loses its fixed negative charge. In this case, plasma proteins enter the filtrate & are found in the urine, a condition known as proteinuria (protein in the urine). Glomerulonephritis may be cause by Strep Throat.

"________ follows salt."

"Water follows salt."

3 Ways GFR is regulated?

1) local automatic adjustments in glomerular pressure; through activities of the SYMPATHETIC division of the autonomic nervous system (ANS); during ‘fight or flight’ the ANS redirects blood flow to other organs; 2) HORMONAL mechanisms result in long-term adjustments in blood pressure & blood volume that stabilize the GFR. 3) LOCAL, automatic changes in the diameters of the afferent arterioles, the efferent arterioles, & the glomerular capillaries can compensate for minor variations in blood pressure. For example, a reduction in blood flow & a decline in glomerular filtration pressure trigger dilation of the afferent arteriole and glomerular capillaries & constriction of the efferent arteriole. This combination keeps glomerular blood pressure & blood flow within normal limits. As a result, glomerular filtration rates remain relatively constant. If blood pressure rises, the afferent arteriole walls become stretched, & smooth muscle cells respond by contracting. The resulting reduction in the diameter of the afferent arterioles decreases glomerular blood flow & keeps the GFR within normal limits.

Negative effects of prolonged strenous exercise on renal system

Autonomic regulation of kidney function occurs primarily through the sympathetic division of the ANS. Sympathetic activity primarily serves to shift blood flow away from the kidneys, which lowers the glomerular filtration rate. Sympathetic activation has both direct & indirect effects on kidney function. The direct effect of sympathetic activation is a powerful constriction of the afferent arterioles, decreasing the GFR & slowing production of filtrate. Triggered by a sudden crisis, such as an acute reduction in blood pressure or a heart attack, sympathetic activation can override the local regulatory mechanisms that act to stabilize the GFR. As the crisis passes & sympathetic activity decreases, the GFR returns to normal. When the sympathetic division changes the regional pattern of blood circulation, blood flow to the kidneys is often affected. This change can further reduce the GFR. For example, during periods of strenuous exercise. As blood flow increases to the skin & skeletal muscles, it decreases to the kidneys. At maximal levels of exertion, renal blood flow may be less than one-quarter of normal resting levels. Such a reduction can create problems for distance swimmers & marathon runners, whose glomerular cells may be damaged by low oxygen levels & the buildup of metabolic wastes over the course of a long event. After such events, protein is commonly lost in the urine, & in some cases, blood appears in the urine. Such problems generally disappear within 48 hours, although a small number of runners experience kidney failure (renal failure) & permanent impairment of kidney function.

4 Hormones that regulate renal function

Angiotensin II ADH Aldosterone Atrial Natriuretic Peptide (ANP)

Angiotensin II

Angiotensin II is produced by the lungs, but triggered by renin in the kidneys & a chain reaction involving the liver. If glomerular pressures remain low because of a decrease in blood volume or pressures (e.g. stress, strenuous exercise, shock), the juxtaglomerular apparatus releases the enzyme renin into the circulation. Renin converts inactive angiotensinogen to angiotensin I, which a converting enzyme activates to angiotensin II. ■ In peripheral capillary beds, it causes a brief but powerful vasoconstriction, elevating blood pressure in the renal arteries. ■ At the nephron, it triggers constriction of the efferent arterioles, elevating glomerular pressures & filtration rates. ■ In the CNS, it triggers the release of ADH, which in turn stimulates the reabsorption of water & sodium ions & induces the sensation of thirst. ■ At the adrenal gland, it stimulates the secretion of aldosterone by the adrenal cortex & of epinephrine and norepinephrine (NE) by the adrenal medullae. The result is a sudden, dramatic increase in systemic blood pressure. At the kidneys, aldosterone stimulates sodium reabsorption along the DCT and collecting system.

Antidiuretic Hormone (ADH)

Antidiuretic hormone (ADH), is produced in the hypothalamus – it increases the water permeability of the DCT & collecting duct, stimulating the reabsorption of water from the tubular fluid, & induces the sensation of thirst, leading to the consumption of additional water. ADH release occurs under angiotensin II stimulation; it also occurs independently, when hypothalamic neurons are stimulated by a reduction in blood pressure or an increase in the solute concentration of the circulating blood. These specialized hypothalamic neurons are called osmoreceptors.

Aldosterone

Aldosterone is produced by the Adrenal Cortex. Aldosterone secretion stimulates the reabsorption of sodium ions & the secretion of potassium ions along the DCT & collecting duct. Aldosterone secretion primarily occurs under angiotensin II stimulation & in response to a rise in the potassium ion concentration of the blood.

Atrial Natriuretic Peptide (ANP)

ANP is secreted by the right atrium of the heart when pressure in the right atrium is increase. It is the only hormone of the 4 regulatory renal hormones that REDUCES blood pressure. The actions of atrial natriuretic peptide (ANP) oppose those of the renin-angiotensin system. This hormone is released by atrial cardiac muscle cells when blood volume & blood pressure are too high. The actions of ANP that affect the kidneys include: -a decrease in the rate of sodium ion reabsorption in the DCT, leading to increased sodium ion loss in the urine; dilation of the glomerular capillaries, which results in increased glomerular filtration & urinary water loss; -the inactivation of the renin-angiotensin system through the inhibition of renin, aldosterone, & ADH secretion. -The net result is an accelerated loss of sodium ions & an increase in the volume of urine produced. This combination lowers blood volume & blood pressure.

Structures & Functions of Ureters, Urinary Bladder, & Urethra

Filtration & urine production ends when the fluid enters the RENAL PELVIS. The ureters, urinary bladder, & urethra are responsible for the transport, storage, & elimination of the urine.

Transitional Epithelium

Transitional epithelium lines the urinary tract from the renal pelvis to the proximal portion of the urethra. Characterized by its ability to stretch / expand to accomodate changes in volume.

Does the urinary bladder have sphincters at the junction of the ureters & bladder?

No, the urinary bladder has one internal urethral sphincter, but no sphincters at the entrance points of the ureters…. Due to the ureters’ slit-like entrance at the posterior of the urinary bladder, there is no need for a sphincter muscle at the junction. Urine continues to flow into the bladder until the bladder becomes distended enough that the pressure closes off the ureteral opening.

What prevents backflow from the urinary bladder?

Each ureter begins at the funnel-shaped renal pelvis & ends at the posterior wall of the bladder; the ureters never enter the peritoneal cavity. Their ureteral openings within the urinary bladder are slit like, a shape that prevents the backflow of urine into the ureters or kidneys when the urinary bladder contracts.

Peristaltic contraction along the ureters

The wall of each ureter contains an inner expandable transitional epithelium, a middle layer of longitudinal & circular bands of smooth muscle, & an outer connective tissue layer continuous with the renal capsule. About every 30 seconds, a peristaltic contraction begins at the renal pelvis & sweeps along the ureter, forcing urine toward the urinary bladder.

Nephrolithiasis

Occasionally, solids composed of calcium deposits, magnesium salts, or crystals of uric acid form within the kidney, ureters, or urinary bladder. These solids are called calculi, or kidney stones, & their presence results in a painful condition known as nephrolithiasis. Kidney stones not only obstruct the flow of urine but may also reduce or prevent filtration in the affected kidney.

Anatomy of the urinary bladder

A full urinary bladder can contain up to a liter of urine. The urinary bladder lies in the pelvic cavity, & only its superior surface is covered by a layer of peritoneum. It is held in position by peritoneal folds (umbilical ligaments) that extend to the umbilicus (navel) & by bands of connective tissue attached to the pelvic & pubic bones. In males, the base of the urinary bladder lies between the rectum & the pubic symphysis. In females, the urinary bladder sits inferior to the uterus & anterior to the vagina. The triangular area within the urinary bladder that is bounded by the ureteral openings and the entrance to the urethra forms the trigone of the bladder. The urethral entrance lies at the apex of this triangle at the lowest point in the bladder. The area surrounding the urethral entrance, called the neck of the urinary bladder, contains a muscular internal urethral sphincter. The smooth muscle of this INTERNAL SPHINCTER PROVIDES INVOLUNTARY CONTROL over the discharge of urine from the bladder.

Histology of urinary bladder

Transitional epithelium continuous with the renal pelvis & the ureters also lines the urinary bladder. This stratified epithelium can tolerate a considerable amount of stretching. The middle layer of the bladder wall consists of inner & outer layers of longitudinal smooth muscle with a circular layer in between. These three layers of smooth muscle form the powerful DETRUSOR MUSCLE of the bladder. Contraction of this muscle compresses the urinary bladder & expels its contents into the urethra.

Urethra

The urethra extends from the neck of the urinary bladder to the exterior of the body. In females, the urethra is very short, extending 2.5-3.0 cm (about 1 in.) from the bladder to its opening in the vestibule anterior to the vagina. In males, the urethra extends from the neck of the urinary bladder to the tip of the penis, about 18-20 cm (7-8 in.) in length. In both sexes, as the urethra passes through the muscular floor of the pelvic cavity, a circular band of skeletal muscle forms the EXTERNAL URETHRAL SPHINCTER. This sphincter consists of skeletal muscle fibers, & its contractions are under VOLUNTARY CONTROL.

Which spincter is voluntary & which is involuntary?

The internal urethral sphincter is formed of involuntary smooth muscle; the external urethral sphincter is formed of voluntary skeletal muscle. They are arranged & controlled in much the same way as the muscles that control defecation. The sensory input that drives the reflex circuits in the sacral cord is also the stretch receptor in the organ wall. Voluntary control of the external sphincter permits some choice of the time and place we void.

Micturation Reflex

Stretch receptors in the wall of the urinary bladder are stimulated as the bladder fills with urine. Afferent sensory fibers in the pelvic nerves carry the resulting impulses to the sacral spinal cord. The fibers’ increased level of activity brings parasympathetic motor neurons in the sacral spinal cord close to threshold & stimulates interneurons that relay sensations to the cerebral cortex. As a result, we become consciously aware of the fluid pressure within the urinary bladder. The urge to urinate usually occurs when the bladder contains about 200 ml of urine. At this time, the motor neurons stimulate the detrusor muscle in the bladder wall. These commands travel over the pelvic nerves & produce a sustained contraction of the urinary bladder. This contraction elevates fluid pressures inside the bladder, but urine ejection cannot occur unless both the internal & external sphincters are relaxed. The relaxation of the external sphincter occurs under voluntary control. Once the external sphincter relaxes, so does the internal sphincter. If the external sphincter does not relax, the internal sphincter remains closed, & the bladder gradually relaxes. A further increase in bladder volume begins the cycle again, usually within an hour. Each increase in urinary volume leads to an increase in stretch receptor stimulation that makes the sensation more acute. Once the volume of the urinary bladder exceeds 500 ml, the micturition reflex may generate enough pressure to force open the internal sphincter. A reflexive relaxation of the external sphincter follows, & urination occurs despite voluntary opposition or potential inconvenience. At the end of normal micturition, less than 10 ml of urine remains in the bladder.

Extracellular Fluid (ECF)

Interstitial Fluid & Plasma (40% of water in the body)

Intracellular Fluid (ICF)

Cytosol / Cytoplasm (60% of water in the body)

highest concentration of cations & anions in ICF?

cations: Potassium anions: Monohydrogen Phosphate

highest concentration of cations & anions in ECF?

PLASMA: cations: Sodium; anions: Chlorine INTERSTITIAL FLUID: cations: Sodium; anions: Chlorine.

Which has the lower concentration of protein; plasma or interstitial fluid?

Interstitial fluid has a much lower concentration of protein compared to plasma.

Homeostasis of Fluids

Water accounts for up to 99 percent of the volume of the fluid outside cells, & it is an essential ingredient of cytoplasm. All of a cell’s operations rely on water as a diffusion medium for the distribution of gases, nutrients, & waste products. I f the water content of the body declines too far, cellular activities are jeopardized: Proteins denature, enzymes cease functioning, & cells ultimately die. To survive, the body must maintain a normal volume & composition in both the extracellular fluid or ECF (the interstitial fluid, plasma, & other body fluids) & the intracellular fluid or ICF (the cytosol). The concentrations of various ions & the pH of the body’s water are as important as its absolute quantity. If concentrations of calcium or potassium ions in the ECF become too high, cardiac arrhythmias develop. A pH outside the normal range can lead to a variety of dangerous conditions. Low pH is especially dangerous because hydrogen ions break chemical bonds, change the shapes of complex molecules, disrupt cell membranes, & impair tissue functions.

Fluid Balance

You are in fluid balance when the amount of water you gain each day is equal to the amount you lose to the environment. Maintaining normal fluid balance involves regulating the content & distribution of water in the ECF & ICF. Because your cells & tissues cannot transport water, fluid balance primarily reflects the creation of ion concentration gradients that are then eliminated by osmosis.

Electrolyte Balance

Electrolytes are ions released through the dissociation of inorganic compounds; they are so named because when in solution they can conduct an electrical current. Each day, your body fluids gain electrolytes from the food & drink you consume, & they lose electrolytes in urine, sweat, & feces. Electrolyte balance exists when there is neither a net gain nor a net loss of any ion in body fluids. Electrolyte balance primarily involves balancing the rates of absorption across the digestive tract with rates of loss at the kidneys.

Acid-base Balance

You are in acid-base balance when the production of hydrogen ions is equal to their loss. When acid-base balance exists, the pH of body fluids remains within normal limits (7.35 – 7.45). Preventing a reduction in pH is a primary problem because normal metabolic operations generate a variety of acids. The kidneys & lungs play key roles in maintaining the acid-base balance of body fluids.

Which contains more water; adipose tissue or skeletal muscle?

Adipose tissue is 10% water, whereas skeletal muscle is 75% water.

Which contains more water; ICF or ECF?

Intracellular fluid contains more of the total body water than does extracellular fluid.

Is plasma ICF or ECF?

Plasma is ECF

Name other minor components of ECF

Lymph, cerebrospinal fluid (CSF), synovial fluid, serous fluids (pleural, pericardial, & peritoneal fluids), aqueous humor, & the fluids of the inner ear (perilymph & endolymph).

3 processes by which fluid & electrolytes are exchanged between ICF & ECF?

Exchange between the ICF and ECF occurs across cell membranes by osmosis, diffusion, & carrier-mediated processes.

Principal ions in the ECF

The principal ions in the ECF are sodium, chloride, & bicarbonate

Principal ions in the ICF

The ICF contains an abundance of potassium, magnesium, & phosphate ions, plus large numbers of negatively charged proteins.

KEY POINT: Osomotic concentrations between ICF & ECF

Despite differences in the concentrations of specific substances, the osmotic concentrations of the ICF & ECF are identical. Osmosis eliminates minor differences in concentration almost at once because most cell membranes are freely permeable to water. Because changes in solute concentrations lead to immediate changes in water distribution, the regulation of water balance & electrolyte balance is tightly intertwined.

Water Balance

Roughly 2500 ml of water is lost each day in urine, feces, & perspiration. The water lost in perspiration varies with the level of activity; in vigorously exercising individuals, the additional losses can reach over 4 liters an hour. Water losses are normally balanced by the gain of fluids through eating (40%), drinking (48%), & metabolic generation (12 %). Metabolic generation of water occurs primarily as a result of mitochondrial ATP production.

Fluid Shift

Water movement between the ECF & the ICF. Water moves to establish osmotic equilibrium. Hypertonic ECF pulls water out of cells (causes crenation). Hypotonic ECF, water shifts into cells (causes cellular swelling).

Osmolarity

Osomotic concentration: Osmolarity is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L).

Fluid Shifts between ICF & ECF

Fluid shifts occur in response to changes in the osmotic concentration, or osmolarity, of the extracellular fluid. If the ECF becomes more concentrated (hypertonic) with respect to the ICF, water will move from the cells into the ECF until equilibrium is restored. If the ECF becomes more dilute (hypotonic) with respect to the ICF, water will move from the ECF into the cells, & the volume of the ICF will increase accordingly. In summary, if the osmolarity of the ECF changes, a fluid shift between the ICF & ECF will tend to oppose the change. Because the volume of the ICF is much greater than that of the ECF, the ICF acts as a "water reserve." Thus, instead of a large change in the osmotic concentration of the ECF, smaller changes occur in both the ECF & the ICF.

Electrolyte Balance between ECF & ICF

You are in electrolyte balance when the rates of gain & loss are equal for each electrolyte in your body. A gain or loss of electrolytes can cause a gain or loss in water. Two cations, Na+ and K+, are major contributors to the osmotic concentrations of the ECF and ICF, & they directly affect the normal functioning of all cells. Sodium is the dominant cation within ECF. More than 90 percent of the osmotic concentration of the ECF results from the presence of sodium salts—principally, sodium chloride (NaCl) & sodium bicarbonate (NaHCO3)—so changes in the osmotic concentration of ECF usually reflect changes in the concentration of sodium ions. Potassium is the dominant cation in the ICF; ECF potassium concentrations are normally low. The most common problems involving electrolyte balance are caused by an imbalance between sodium gains & losses. Problems with potassium balance are less common but significantly more dangerous than those related to sodium balance.

Sodium Ion Balance
("Water follows salt.")

The amount of sodium in the ECF represents a balance between sodium ion absorption at the digestive tract & sodium ion excretion at the kidneys & other sites. The rate of uptake varies directly with the amount included in the diet. Sodium losses occur primarily by excretion in urine & through perspiration. THE KIDNEYS ARE THE MOST IMPORTANT SITES FOR REGULATING SODIUM ION LOSSES. In response to circulating aldosterone, the kidneys reabsorb sodium ions (which decreases sodium loss), & in response to atrial natriuretic peptide (ANP), the kidneys increase the loss of sodium ions. Whenever the rate of sodium intake or output changes, a corresponding gain or loss of water tends to keep the Na+ concentration constant. For example, eating a heavily salted meal will not raise the sodium ion concentration of body fluids because as sodium chloride crosses the digestive epithelium, osmosis brings additional water into the ECF. This is why individuals with high blood pressure are told to restrict their salt intake; dietary salt is absorbed, & because "water follows salt," blood volume—&, thus, blood pressure—increases.

Potassium Ion Balance
(Aldosterone stimulates potassium ion excretion)

Roughly 98% of the potassium content of the body lies within the ICF. Cells expend energy to recover potassium ions as the ions diffuse out of the cytoplasm & into the ECF. The K+ concentration of the ECF is relatively low & represents a balance between the rate of gain across the digestive epithelium & the rate of loss in urine. The rate of gain is proportional to the amount of potassium in the diet. The rate of loss is strongly affected by aldosterone. Urinary potassium losses are controlled through adjustments in the rate of active secretion along the distal convoluted tubules of the kidneys. The ion pumps sensitive to aldosterone reabsorb sodium ions from the filtrate in exchange for potassium ions from the interstitial fluid. High plasma concentrations of potassium ions also stimulate aldosterone secretion directly. When potassium levels rise in the ECF, aldosterone levels climb, & additional potassium ions are lost in the urine. When potassium levels fall in the ECF, aldosterone levels decline, & potassium ions are conserved.

Where is aldosterone produced?

Adrenal Cortex (remember: ‘AD’ ‘Renal’; ‘near’ ‘kidneys’)

Buffers & Buffer Systems

The carbonic acid reaction shows the impact of ventilation on pH & bicarbonate concentration. Since the reactions are completely reversible, increasing PCO2 produces H+ (& lowers pH) & vice versa. The brain stem, by controlling the rate of alveolar ventilation, constantly adjusts plasma pH.

Acid-balance

The pH of your body fluids represents a balance among the acids, bases, & salts in solution. The pH of the ECF normally remains within relatively narrow limits, usually 7.35-7.45. Any deviation from the normal range is extremely dangerous because changes in hydrogen ion concentrations disrupt the stability of cell membranes, alter protein structure, & change the activities of important enzymes. When the pH of blood falls below 7.35, the physiological state called acidosis exists. Alkalosis exists if the pH exceeds 7.45. These conditions affect virtually all systems, but the nervous & cardiovascular systems are particularly sensitive to pH fluctuations. Severe acidosis (pH below 7.0) can be deadly because CNS function deteriorates, & the individual becomes comatose; cardiac contractions grow weak & irregular, & signs of heart failure develop; & peripheral vasodilation produces a dramatic drop in blood pressure, & circulatory collapse can occur. Acidosis & alkalosis are both dangerous, but in practice, problems with acidosis are much more common because several acids (including carbonic acid) are generated by normal cellular activities.

Carboxylic Acid

A weak acid, therefore it can accept or donate hydrogen ions easily. (Carbonic acid is a Carboxylic acid)

Carbonic Acid

Carbonic acid (H2CO3) is an important acid in body fluids. At the lungs, carbonic acid breaks down into carbon dioxide & water; the carbon dioxide diffuses into the alveoli. In peripheral tissues, carbon dioxide in solution interacts with water to form carbonic acid. The carbonic acid molecules then dissociate to produce hydrogen ions & bicarbonate ions. CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3- carbon dioxide + water ↔ carbonic acid ↔ hydrogen ion + bicarbonate ion This reaction occurs spontaneously in body fluids, but it occurs very rapidly in the presence of carbonic anhydrase, an enzyme found in many cell types, including red blood cells, liver & kidney cells, & parietal cells of the stomach.

Carbon Dioxide & Plasma pH

Because most of the carbon dioxide in solution is converted to carbonic acid, & most of the carbonic acid dissociates, the partial pressure of carbon dioxide (PCO2) & the pH are inversely related: When carbon dioxide concentrations rise, additional hydrogen ions & bicarbonate ions are released, and the pH goes down. (key-point: the greater the concentration of hydrogen ions, the lower the pH value.) The PCO2 is the most important factor affecting the pH in body tissues. At the alveoli, carbon dioxide diffuses into the atmosphere, the number of hydrogen ions & bicarbonate ions drops, and the pH rises.

Metabolic Acids
(acids produced organically)

Organic acids, or metabolic acids, are generated during normal metabolism. Some are generated during the catabolism of amino acids, carbohydrates, or lipids. Examples are lactic acid produced during anaerobic metabolism of pyruvic acid, & ketone bodies produced in the breakdown of fatty acids. Under normal conditions, metabolic acids are recycled or excreted rapidly, & significant accumulations do not occur.

BUFFER SYSTEMS:
-Resist changes in pH
-Consist of a weak acid & an anion
dissociation product
-3 major buffer systems in the body:
-protein buffer system (in ECF & ICF)
-carbonic acid-bicarbonate buffer
system (in ECF)
-phosphate buffer system (in ICF)

The acids produced in the course of normal metabolic operations are temporarily neutralized by buffers & buffer systems in body fluids. Buffers are dissolved compounds that can provide or remove hydrogen ions (H+), thereby stabilizing the pH of a solution. Buffers include weak acids that can donate H+ & weak bases that can absorb H+. A buffer system consists of a combination of a weak acid & its dissociation products: a hydrogen ion & an anion. The body has three major buffer systems, each with slightly different characteristics & distributions: the protein buffer system, the carbonic acid-bicarbonate buffer system, & the phosphate buffer system.

Protein Buffer Systems (plasma & Hgb)

Protein buffer systems contribute to the regulation of pH in both the ECF & ICF. Protein buffer systems depend on the ability of amino acids to respond to changes in pH by accepting or releasing hydrogen ions. If pH climbs, the carboxyl group (COOH) of the amino acid can dissociate, releasing a hydrogen ion. If pH drops, the amino group (NH2) can accept an additional hydrogen ion, forming an amino ion (NH3+). The plasma proteins & hemoglobin in red blood cells contribute to the buffering capabilities of the blood. Interstitial fluids contain extracellular protein fibers & dissolved amino acids that also help regulate pH. In the ICF of active cells, structural and other proteins provide an extensive buffering capability that prevents destructive pH changes when organic acids, such as lactic acid, are produced by cellular metabolism.

Carbonic Acid-Bicarbonate Buffer System

The carbonic acid-bicarbonate buffer system is an important buffer system in the ECF. With the exception of red blood cells, your cells generate carbon dioxide 24 hours a day. Most of the carbon dioxide is converted to carbonic acid, which then dissociates into a hydrogen ion & a bicarbonate ion. The carbonic acid & its dissociation products constitute the carbonic acid-bicarbonate buffer system; the carbonic acid acts as a weak acid, & the bicarbonate ion acts as a weak base. The net effect of this buffer system is that CO2 + H20 ↔ H+ + HCO3- If hydrogen ions are removed, they will be replaced through the combining of water with carbon dioxide; if hydrogen ions are added, most will be removed through the formation of carbon dioxide & water. The primary role of the carbonic acid-bicarbonate buffer system is to prevent pH changes caused by organic (metabolic) acids. Hydrogen ions released through the dissociation of these acids combine with bicarbonate ions, producing water & carbon dioxide. Carbon dioxide can then be excreted at the lungs. This buffering system can cope with large amounts of acid because body fluids contain an abundance of bicarbonate ions, known as the bicarbonate reserve. When hydrogen ions enter the ECF, the bicarbonate ions that combine with them are replaced by the bicarbonate reserve. The phosphate buffer system consists of an anion, dihydrogen phosphate (H2PO4−), which is a weak acid. The dihydrogen phosphate ion & its dissociation products constitute the phosphate buffer system: H2PO4 ↔ H+ + HPO42- Dihydrogen phosphate ↔ hydrogen ion ↔ monohydrogen phosphate In solution, dihydrogen phosphate (H2PO4−) reversibly dissociates into a hydrogen ion & monohydrogen phosphate (HPO42−). In the ECF, the phosphate buffer system plays only a supporting role in the regulation of pH, primarily because the concentration of bicarbonate ions far exceeds that of phosphate ions. However, the phosphate buffer system is quite important in buffering the pH of the ICF, where the concentration of phosphate ions is relatively high.

Renal & Respiratory Compensations for pH Disturbances:

RESP: Raises/lowers CO2 levels;
RENAL: Varies H+ secretion
& Bicarb reabsorption.

Buffer systems can tie up excess hydrogen ions (H+), but because the H+ has not been eliminated, buffer systems provide only a temporary solution. For homeostasis to be preserved, the captured H+ must ultimately be removed from body fluids. The problem is that the supply of buffer molecules is limited; once a buffer binds a H+, it cannot bind any more H+. With the buffer molecules tied up, the capacity of the ECF to absorb more H+ is reduced, & pH control is impossible. The maintenance of acid-base balance involves balancing hydrogen ion losses & gains. In this "balancing act," the respiratory & renal mechanisms support the buffer systems by: secreting or absorbing hydrogen ions, controlling the excretion of acids & bases, & generating additional buffers. It is the combination of buffer systems & these respiratory and renal mechanisms that maintain body pH within narrow limits.

Respiratory pH Compensation

…a change in the respiratory rate that helps stabilize the pH of the ECF. Respiratory compensation occurs whenever pH exceeds normal limits. Respiratory activity has a direct effect on the carbonic acid-bicarbonate buffer system. Increasing or decreasing the rate of respiration alters pH by lowering or raising the partial pressure of CO2 (PCO2). Changes in PCO2 have a direct effect on the concentration of hydrogen ions in the plasma. When the PCO2 rises, the pH declines, & when the PCO2 decreases, the pH increases. A rise in PCO2 stimulates chemoreceptors in the carotid & aortic bodies and within the CNS; a fall in the PCO2 inhibits them. Stimulation of the chemoreceptors leads to an increase in the respiratory rate. As the rate of respiration increases, more CO2 is lost at the lungs, so the PCO2 returns to normal levels. When the PCO2 of the blood or CSF declines, respiratory activity becomes depressed, the breathing rate falls, & the PCO2 in the extracellular fluids rises.

Renal pH Compensation

… a change in the rates of hydrogen ion & bicarbonate ion secretion or absorption by the kidneys in response to changes in plasma pH. Under normal conditions, the body generates H+ through the production of metabolic acids. The H+ these acids release must be excreted in the urine to maintain acid-base balance. Glomerular filtration puts hydrogen ions, carbon dioxide, & the other components of the carbonic acid-bicarbonate & phosphate buffer systems into the filtrate. The kidney tubules then modify the pH of the filtrate by secreting hydrogen ions or reabsorbing bicarbonate ions.

2 Classes of Acid-Base Disorders

When buffering mechanisms are severely stressed, pH wanders outside normal limits, producing symptoms of alkalosis or acidosis. Respiratory acid-base disorders result when abnormal respiratory function causes an extreme rise or fall in CO2 levels in the ECF. Metabolic acid-base disorders result from the generation of organic acids or by conditions affecting the concentration of bicarbonate ions in the ECF. When a respiratory acid-base disorder is present, the carbon dioxide level of the ECF is abnormal. Metabolic acid-base disorders are caused by the generation of organic acids or by conditions affecting the concentration of bicarbonate ions in the ECF. Respiratory compensation alone can often restore normal acid-base balance in individuals suffering from respiratory disorders. In contrast, compensation mechanisms for metabolic disorders may be able to stabilize pH, but other aspects of acid-base balance (buffer system function, bicarbonate levels, and PCO2) remain abnormal until the underlying metabolic problem is corrected. Respiratory acidosis develops when the respiratory system is unable to eliminate all of the CO2 generated by peripheral tissues. The primary indication is low plasma pH due to hypercapnia, an elevated plasma PCO2. As carbon dioxide levels climb, hydrogen & bicarbonate ion concentrations rise as well. Other buffer systems can tie up some of the hydrogen ions, but once the combined buffering capacity has been exceeded, pH begins to fall rapidly.

Respiratory Acidosis

Respiratory acidosis represents the most frequent challenge to acid-base balance. The usual cause is hypoventilation, an abnormally low respiratory rate. Because tissues generate carbon dioxide at a rapid rate, even a few minutes of hypoventilation can cause acidosis, reducing the pH of the ECF to as low as 7.0. Under normal circumstances, chemoreceptors monitoring the PCO2 of the plasma & CSF will eliminate the problem by stimulating increases in breathing rates. Problems with respiratory alkalosis are relatively uncommon. This condition develops when respiratory activity reduces plasma PCO2 to below-normal levels, a condition called hypocapnia. Temporary hypocapnia can be produced by hyperventilation, when increased respiratory activity leads to a reduction in arterial PCO2. Continued hyperventilation can elevate pH to levels as high as 7.8-8. This condition usually corrects itself, for the reduction in PCO2 removes the stimulation for the chemoreceptors, & the urge to breathe fades until carbon dioxide levels have returned to normal. Respiratory alkalosis caused by hyperventilation seldom persists long enough to cause a clinical emergency.

Metabolic Acidosis

Metabolic acidosis is the second most common type of acid base imbalance. The most frequent cause is the production of large quantities of metabolic acids such as lactic acid or ketone bodies. Metabolic acidosis can also be caused by an impaired ability to excrete hydrogen ions at the kidneys, & any condition accompanied by severe kidney damage can result in metabolic acidosis. Compensation for metabolic acidosis usually involves a combination of respiratory & renal mechanisms. Hydrogen ions interacting with bicarbonate ions form carbon dioxide molecules that are eliminated at the lungs, while the kidneys excrete additional hydrogen ions into the urine & generate bicarbonate ions that are released into the ECF. Metabolic alkalosis occurs when bicarbonate ion concentrations become elevated. The bicarbonate ions then interact with hydrogen ions in solution, forming carbonic acid; the reduction in H+ concentrations produces alkalosis. Cases of severe metabolic alkalosis are relatively rare. A temporary metabolic alkalosis occurs during meals, when large numbers of bicarbonate ions are released into the ECF during the secretion of HCl by the parietal cells of the stomach. (Hydrogen ions and bicarbonate ions are formed from CO2 and H2O within the parietal cells, & the bicarbonate ions are released into the blood in exchange for chloride ions.) Serious metabolic alkalosis may result from bouts of repeated vomiting, because the stomach continues to generate stomach acids to replace those that are lost. As a result, the HCO3 concentration of the ECF continues to rise. Compensation for metabolic alkalosis involves a reduction in pulmonary ventilation, coupled with the increased loss of bicarbonates in the urine.

Most common & acute acid-base disorder?

Respiratory Acidosis, which develops when respiratory activity cannot keep pace with the rate of carbon dioxide generation in peripheral tissue.

7 age-related change in Urinary System

Loss of functional nephrons; Reduced GFR; Reduced response to ADH & Aldosterone; Urinary retention in men with protate enlargement; Drop in body water & mineral content (results in less dilution of waste products, toxins, & administered drugs); Disorders of fluid, electrolyte, or acid-base balance. Increased incidence of disorders affecting major systems with increasing age (basically, you’re S.O.L….)

Where is ADH produced?

The hypothalamus (it is ‘released’ in the posterior pituitary gland)

Where is Aldosterone secreted?

The Adrenal Cortex (remember: "O" AldOsterOne = C’O’rtex) ("E" EpinEphrinE = M’E’dulla)

Which atrium secretes ANP?

Right atrium (in response to being stretched)

Which organs are involved in the production of Angiotensin II?

Renin from the kidneys; Angiotensin I from the liver; Angiotensin II from the lungs…

Other name for Vasopressin?

ADH

Integration with other systems

INTEGUMENTARY: Water & electrolyte losse in perspiration affect plasma volume & composition. Effects are most apparent when losses are extreme, as occurs during maximum sweat production. Small amounts of metabolic wastes, including urea, are also excreted in perspiration. RESPIRATORY: The lungs remove the carbon dioxide generated by cells. Small amounts of other compounds, such as acetone & water, evaporate into the alveoli & are eliminated during exhalation. DIGESTIVE: The liver excretes metabolic waste products in bile, & a variable amount of water is lost in feces.

The ureter is indicated by ________.

label b

The renal cortex is indicated by ________.

label g

The renal pelvis is indicated by ________.

label e

A calyx is indicated by ________.

label a

The nephron loop, or loop of Henle, is indicated by ________.

label j

The peritubular capillaries are indicated by ________.

label n

The glomerular capsule (Bowman’s capsule) is indicated by ________.

label a

The proximal convoluted tubule is indicated by ________.

label m

The efferent arteriole is indicated by ________.

label c

The cortical radiate artery is indicated by ________.

label d

The glomerulus is indicated by ________.

label o

The medial indentation where the ureter, blood vessels, and nerves are connected to the kidney is called the ________.

renal hilum

There are three regions of the kidney; the outermost region is known as the ________.

renal cortex

Renal (medullary) pyramids are separated by extensions of cortex-like tissue called the ________.

renal columns

The blood vessel carrying blood from the aorta into the kidney is the ________.

renal artery

The functional unit of the kidney that filters blood and forms urine is the ________.

nephron

The blood vessel directly feeding the glomerulus with blood from the cortical radiate artery is the ________.

afferent arteriole

Filtrate formed during glomerular filtration is captured by the ________.

glomerular (Bowman’s) capsule

The process that removes ions such as potassium and hydrogen from the blood and places them into the nephron for removal from the body as urine is known as ________.

tubular secretion

Filtrate contains everything in blood plasma except for ________.

blood proteins

Specific gravity is the term used to compare how much heavier urine is than ________.

distilled water

The tube connecting each kidney to the urinary bladder is the ________.

ureter

The smooth triangular region of the urinary bladder base that is outlined by the openings of the two ureters and the urethra is called the ________.

trigone

Inflammation of the urethra is called ________.

urethritis

The involuntary sphincter that keeps the urethra closed when urine is not being passed is called the ________.

internal urethral sphincter

The inability to voluntarily control the external urethral sphincter is known as ________.

incontinence

The process of emptying the urinary bladder is known as voiding or ________.

micturition

About two-thirds of body fluid is found within living cells; this fluid is called the ________.

intracellular fluid or ICF

The driving force for water intake is ________.

the thirst mechanism

Highly sensitive cells within the hypothalamus that react to changes in blood composition and cause the release of antidiuretic hormone (ADH) when appropriate are called ________.

osmoreceptors

The abnormal condition that results from the lack of ADH release, causing huge amounts of very dilute urine to be voided, is called ________.

diabetes insipidus

The hormone released by the posterior pituitary to prevent excessive water loss in the urine is ________.

antidiuretic hormone (ADH)

Arterial blood pH above 7.45 is considered to be ________.

alkalosis

A strong acid will dissociate and liberate more ________ ions in water than a weak acid.

hydrogen

The kidneys can help maintain a rising blood pH by excreting ________ ions and reabsorbing ________ ions by the tubule cells.

bicarbonate; hydrogen

The need to urinate frequently at night, which plagues over 50% of the elderly, is called ________.

nocturia

Untreated streptococcal infections in childhood that can lead to the kidney infection characterized by antigen-antibody complexes clogging the glomerular filters is known as ________.

glomerulonephritis

A feeling that it is necessary to void, which is experienced more regularly in the elderly, is known as ________.

urgency

Which one of the following is NOT one of the functions of the kidneys?
A) manufacture urine
B) convert vitamin D from its inactive to its active form
C) dispose of metabolic waste products
D) produce hormones that assist in digestion
E) regulate blood volume

produce hormones that assist in digestion

Which organ filters blood, regulates blood volume and chemical makeup?

kidney

Which one of the following terms describes the location of the kidneys?
A) suprarenal
B) retroperineal
C) adrenal
D) intraperitoneal
E) retroperitoneal

retroperitoneal

What region of the kidney is deep to the renal cortex?

renal medulla

The triangular regions of the kidneys that are striped in appearance and separated by the renal columns are the ________.

renal (medullary) pyramids

As venous blood is drained from the kidney, which path does it follow ________.

cortical radiate veins, arcuate veins, interlobar veins, renal vein

Items in the blood that are NOT filtered will travel from the glomerulus to the ________.

efferent arteriole

The capillary bed surrounding the renal tubule is the ________.

peritubular capillaries

Starting from the glomerular capsule, the correct order of the renal tubule regions is ________.

proximal convoluted tubule, nephron loop (loop of Henle), distal convoluted tubule

The portion of the renal tubule closest to the glomerulus is the ________.

proximal convoluted tubule (PCT)

Most nephrons are located within the renal ________.

cortex

The percentage of filtrate eventually reabsorbed into the bloodstream is closest to ________.

99%

Of the capillary beds associated with each nephron, the one that is both fed and drained by arterioles is the ________.

glomerulus

Filtrate typically does NOT contain ________.

blood proteins

The nonselective, passive process performed by the glomerulus that forms blood plasma without blood proteins is called ________.

glomerular filtration

Nitrogenous waste products, such as urea and uric acid, are ________.

filtered but poorly reabsorbed

Which one of the following is NOT a substance typically reabsorbed by the tubules under normal healthy conditions?
A) glucose
B) urea
C) amino acids
D) sodium
E) water

urea

In a 24-hour period, a typical volume of urine production is ________.

1.4 l

Which one of the following substances is normally found in urine?
A) blood proteins
B) red blood cells
C) hemoglobin
D) white blood cells
E) creatinine

creatinine

Determine the possible cause of bile pigments in the urine ________.

liver disease

Dilute urine would have a specific gravity closest to ________.

1.001

Renal calculi can lead to ________.

hematuria

Why is the trigone of the urinary bladder clinically important?

Infections tend to persist in the trigone.

The urinary bladder is able to expand as urine accumulates within it due to the presence of ________.

transitional epithelium

Urine is transported from the urinary bladder to the outside of the body by the ________.

urethra

The average adult urinary bladder is moderately full with ________ of urine within it.

500 mL

The voluntarily controlled sphincter fashioned by skeletal muscle at the point where the urethra passes through the pelvic floor is called the ________.

external urethral sphincter

The process of emptying the urinary bladder is referred to as voiding or ________.

micturition

In males, the urethra is part of both the urinary system and ________.

reproductive system

The micturition reflex forces urine into the upper part of the ________.

urethra

In one 24-hour period, the kidneys of an average-sized healthy adult filter approximately ________ through their glomeruli into the tubules.

150-180 liters of blood plasma

Who has the highest percentage of water in the body?

infant

Which one of the following is NOT one of the major roles of the kidneys in normal healthy adults?
A) excretion of nitrogen-containing wastes
B) maintenance of water balance of the blood
C) maintenance of electrolyte balance of the blood
D) conversion of ammonia to bicarbonate ion
E) ensuring proper blood pH

conversion of ammonia to bicarbonate ion

Which of the following is the major stimulus for the thirst mechanism?
A) hunger
B) decreased urination
C) increased osmolarity of blood plasma
D) defecation
E) increased saliva production

increased osmolarity of blood plasma

Extracellular fluid is found everywhere in the body EXCEPT ________.
A) within living cells
B) blood plasma
C) interstitial fluid
D) cerebrospinal fluid
E) humors of the eye and lymph

within living cells

The main hormone that acts on the kidneys to regulate sodium ion concentration of the extracellullar fluid (ECF) is ________.

aldosterone

Antidiuretic hormone prevents excessive water loss by promoting water reabsorption in the ________.

collecting duct

Aldosterone does NOT directly or indirectly regulate ________.

glucose

What stimulates the release of renin from the juxtaglomerular (JG) apparatus?

low blood pressure

What role does angiotensin II play in restoring blood pressure to normal?

Angiotensin II causes blood vessels to vasoconstrict.

The chemical buffer system that includes carbonic acid and its salt, which ties up the H+ released by strong acids, is called the ________.

bicarbonate buffer system

Which of these chemicals dissociates completely and liberates all the hydrogen ions when dissolved in water?
A) strong acids
B) weak acids
C) neutral substances
D) weak bases
E) strong bases

strong acids

Which system removes excess carbon dioxide from the blood?

respiratory system

When blood pH begins to rise, the respiratory control centers in the brain are ________.

depressed

How does the urinary system respond to blood that has become acidic?

both secrete more hydrogen ions and reabsorb more bicarbonate ions

The need to get up during the night to urinate is called ________.

nocturia

The degenerative condition in which blisterlike sacs (cysts) containing urine form on the kidneys and obstruct urine drainage is called ________.

polycystic kidney

Hypospadias is a condition of male children that involves ________.

opening of the urethra on the ventral surface of the penis

Childhood streptococcal infections that go untreated can lead to ________.

glomerulonephritis

Control of the voluntary urethral sphincter in normal children is related to ________.

nervous system development

From childhood through late middle age, one of the most common bacteria to infect and inflame the urinary tract and cause urethritis and cystitis is ________.

Escherichia coli

Water and solutes are forced from the blood into the glomerular capsule of the nephron

glomerular filtration

Water, glucose, amino acids, and needed ions are moved from the filtrate back into the blood

tubular reabsorption

Aldosterone promotes sodium and thus water to move from the filtrate through the tubule cells into the blood

tubular reabsorption

Antidiuretic hormone (ADH) promotes the movement of water from the filtrate back into the blood of the peritubular capillaries

tubular reabsorption

Unneeded substances such as potassium, urea, and creatinine are moved from the blood of the peritubular capillaries into the filtrate

tubular secretion

Opposite process to tubular reabsorption

tubular secretion

Cup-shaped extensions of the pelvis that enclose the tips of the renal (medullary) pyramids

calyces

Outer, lighter region of the kidney

renal cortex

Blood is transported away from the kidney in this vessel

renal vein

Cortex-like extensions that separate the renal (medullary) pyramids

renal columns

Darker, reddish-brown internal area of the kidney

renal medulla

Triangular regions with a striped appearance

renal (medullary) pyramids

Flat, basinlike cavity medial to the renal hilum of the kidney

renal pelvis

Tube that drains urine from the kidney to the urinary bladder

ureter

Muscular sac suitable for temporary urine storage

urinary bladder

Transports urine and sperm in males

urethra

Contains three layers of smooth muscle known as the detrusor muscle

urinary bladder

Contains an area called the trigone formed by the openings of the ureters and urethra

urinary bladder

Micturition reflex causes this organ to go into contractions

urinary bladder

Which of these is NOT normally found in urine?

glucose

The medial indentation where the ureter, blood vessels, and nerves are connected to the kidney is called the __________.

renal hilum

There are three regions of the kidney; the outermost region is known as the _________

renal cortex

Renal pyramids are separated by extensions of cortex-like tissue called the _____

renal columns

The blood vessel carrying blood from the aorta into the kidney is the __________.

renal artery

The functional unit of the kidney that filters blood and forms urine is the ________

nephron

The blood vessel directly feeding the glomerulus with blood from the cortical radiate artery is the __________.

afferent arteriole

The three processes occurring in the nephron that lead to the formation of urine are __________.

glomerular filtration, tubular reabsorption, tubular secretion

The process that removes ions such as potassium and hydrogen from the blood and places them into the nephron for removal from the body as urine is known as __________.

tubular secretion

Urine pH is usually around a pH of __________.

6

Specific gravity is the term used to compare how much heavier urine is than _____

distilled water

The tubes connecting the kidney to the bladder are the __________.

ureters

The smooth triangular region of the bladder base that is outlined by the openings of the two ureters and the urethra is called the __________.

trigone

Urinary bladder inflammation often caused by bacterial infection is called ____

cystitis

The involuntary sphincter that keeps the urethra closed when urine is not being passed is called the __________.

internal urethral sphincter

The inability to voluntarily control the external urethral sphincter is known as ____

incontinence

The process of emptying the bladder is known as voiding or __________.

micturition

About two-thirds of body fluid is found within living cells; this fluid is called the __________.

intracellular fluid or ICF

Sodium ion content of the extracellular fluid (ECF) is largely regulated by an adrenal cortex hormone called __________.

aldosterone

Highly sensitive cells within the hypothalamus that react to changes in blood composition and cause the release of antidiuretic hormone (ADH) when appropriate are called _______

osmoreceptors

The abnormal condition that results from the lack of ADH release, causing huge amounts of very dilute urine to be voided, is called __________.

diabetes insipidus

The primary urinary symptom of Addison’s disease (hypoaldosteronism) is called __________.

polyuria

Arterial blood pH between 7.35 and 7.0 is called __________.

physiological acidosis

A strong acid will dissociate and liberate more __________ ions in water than a weak acid.

hydrogen or H+

The kidneys can help maintain a rising blood pH by excreting __________ ions and reabsorbing __________ ions by the tubule cells.

bicarbonate; hydrogen

The need to urinate frequently at night, which plagues over 50% of the elderly, is called __________.

nocturia

Untreated streptococcal infections in childhood that can lead to the kidney infection characterized by antigen-antibody complexes clogging the glomerular filters is known as __________.

glomerulonephritis

A feeling that it is necessary to void, which is experienced more regularly in the elderly, is known as __________.

urgency

Which one of the following is NOT one of the functions of the kidneys:
A) manufacture urine
B) convert vitamin D from its inactive to its active form
C) dispose of metabolic waste products
D) produce hormones that assist in digestion
E) regulate blood volume

D) produce hormones that assist in digestion

Which organ filters blood, regulates blood volume and chemical makeup:
A) kidney
B) ureter
C) liver
D) urinary bladder
E) urethra

A) kidney

Which one of the following terms describes the location of the kidneys:
A) suprarenal
B) retroperineal
C) adrenal
D) intraperitoneal
E) retroperitoneal

E) retroperitoneal

The kidneys are aided in the excretion of fluids by the:
A) lungs
B) skin
C) hair
D) lungs and skin
E) skin and hair

D) lungs and skin

The triangular regions of the kidneys that are striped in appearance and separated by the renal columns are the:
A) renal cortex
B) renal medulla
C) renal pyramids
D) renal pelvis
E) calyces

C) renal pyramids

As venous blood is drained from the kidney, which path does it follow:
A) cortical radiate veins, arcuate veins, interlobar veins, renal vein
B) renal vein, interlobar veins, segmental veins, arcuate veins
C) arcuate veins, cortical radiate veins, interlobar veins, renal vein
D) renal vein, segmental veins, interlobar veins, arcuate veins, cortical radiate veins
E) cortical radiate veins, arcuate veins, interlobar veins, segmental veins, renal vein

A) cortical radiate veins, arcuate veins, interlobar veins, renal vein

As filtrate flows through the proximal convoluted tubule, where does it travel next:
A) collecting duct
B) glomerulus
C) loop of Henle
D) glomerular (Bowman’s) capsule
E) distal convoluted tubule

C) loop of Henle

The capillary bed surrounding the renal tubule is the:
A) afferent arteriole
B) segmental arteries
C) peritubular capillaries
D) cortical radiate arteries
E) glomerular capillaries

C) peritubular capillaries

Starting from the glomerular capsule, the correct order of the renal tubule regions is:
A) proximal convoluted tubule, distal convoluted tubule, loop of Henle
B) distal convoluted tubule, loop of Henle, proximal convoluted tubule
C) loop of Henle, proximal convoluted tubule, distal convoluted tubule
D) proximal convoluted tubule, loop of Henle, distal convoluted tubule
E) distal convoluted tubule, proximal convoluted tubule, loop of Henle

D) proximal convoluted tubule, loop of Henle, distal convoluted tubule

The portion of the renal tubule closest to the glomerulus is the:
A) collecting duct
B) proximal convoluted tubule (PCT)
C) glomerular (Bowman’s) capsule
D) distal convoluted tubule (DCT)
E) loop of Henle

B) proximal convoluted tubule (PCT)

Most nephrons are located within the renal:
A) pelvis
B) calyces
C) medulla
D) pyramids
E) cortex

E) cortex

The percentage of filtrate eventually reabsorbed into the bloodstream is closest to:
A) 10%
B) 25%
C) 50%
D) 80%
E) 99%

E) 99%

Of the capillary beds associated with each nephron, the one that is both fed and drained by arterioles is the:
A) peritubular capillaries
B) pyramidal capillaries
C) glomerulus
D) Henle capillaries
E) Bowman’s capillaries

C) glomerulus

Filtrate typically does NOT contain:
A) water
B) blood proteins
C) glucose
D) ions
E) amino acids

E) amino acids

The nonselective, passive process performed by the glomerulus that forms blood plasma without blood proteins is called:
A) absorption
B) secretion
C) filtration
D) tubular reabsorption
E) glomerular reabsorption

C) filtration

Uric acid, a nitrogenous waste product, results from the metabolism of:
A) creatinine
B) nucleic acids
C) proteins
D) amino acids
E) salt

B) nucleic acids

Which one of the following is NOT a substance typically reabsorbed by the tubules under normal healthy conditions:
A) glucose
B) urea
C) amino acids
D) sodium
E) water

B) urea

Kidney inflammation is called:
A) anuria
B) pyelonephritis
C) glucosuria
D) hydronephrosis
E) incontinence

B) pyelonephritis

Which one of the following substances is normally found in urine:
A) blood proteins
B) red blood cells
C) hemoglobin
D) white blood cells
E) creatinine

E) creatinine

The presence of pus in urine is called:
A) glycosuria
B) pyuria
C) bilirubinuria
D) hematuria
E) proteinuria

B) pyuria

Dilute urine would have a specific gravity closest to:
A) 0.005
B) 1.001
C) 1.010
D) 1.020
E) 1.030

B) 1.001

The tube connecting the renal hilum of the kidney to the bladder is the:
A) urethra
B) proximal convoluted tubule
C) distal convoluted tubule
D) ureter
E) collecting duct

D) ureter

Smooth muscle in the walls of the urine move urine along to the bladder by:
A) peristalsis
B) segmentation
C) defecation
D) micturition
E) regurgitation

A) peristalsis

The bladder is able to expand as urine accumulates within it due to the presence of:
A) simple squamous epithelium
B) transitional epithelium
C) stratified squamous epithelium
D) pseudostratified epithelium
E) sphincters

B) transitional epithelium

Urine is transported from the bladder to the outside of the body by the:
A) ureter
B) trigone
C) prostate gland
D) urethra
E) collecting duct

D) urethra

The average adult bladder is moderately full with __________ of urine within it.
A) 100 mL
B) 500 mL
C) 1 liter
D) 2 liters
E) 1 gallon

B) 500 mL

The voluntarily controlled sphincter fashioned by skeletal muscle at the point where the urethra passes through the pelvic floor is called the:
A) internal urethral sphincter
B) internal anal sphincter
C) external urethral sphincter
D) trigone
E) detrusor sphincter

C) external urethral sphincter

The process of emptying the bladder is referred to as voiding or:
A) tubular secretion
B) filtration
C) tubular reabsorption
D) incontinence
E)micronutrition

E)micronutrition

In males, the urethra is part of both the urinary system and:
A) endocrine system
B) digestive system
C) immune system
D) respiratory system
E) reproductive system

E) reproductive system

Enlargement of the prostate that surrounds the neck of the bladder in adult men is called __________ , which may cause voiding difficulty.
A) atrophy
B) dystrophy
C) hyperplasia
D) hypoplasia
E) eutrophy

C) hyperplasia

In one 24-hour period, the kidneys of an average-sized healthy adult filter approximately __________ through their glomeruli into the tubules.
A) 10-15 liters of blood plasma
B) 50-75 liters of blood plasma
C) 100-125 liters of blood plasma
D) 150-180 liters of blood plasma
E) 200-240 liters of blood plasma

D) 150-180 liters of blood plasma

Who has the highest percentage of water in the body:
A) 30 year old female, overweight
B) 90 year old male, normal weight
C) 9 month old baby
D) 30 year old male, muscular build
E) 80 year old female, normal weight

C) 9 month old baby

Which one of the following is NOT one of the major roles of the kidneys in normal healthy adults:
A) excretion of nitrogen-containing wastes
B) maintenance of water balance of the blood
C) maintenance of electrolyte balance of the blood
D) conversion of ammonia to bicarbonate ion
E) ensuring proper blood pH

D) conversion of ammonia to bicarbonate ion

Which of the following is the major stimulus for the thirst mechanism:
A) hunger
B) decreased urination
C) increased osmolarity of blood plasma
D) defecation
E) increased saliva production

C) increased osmolarity of blood plasma

Extracellular fluid is found everywhere in the body EXCEPT:
A) within living cells
B) blood plasma
C) interstitial fluid
D) cerebrospinal fluid
E) humors of the eye and lymph

A) within living cells

The main hormone that acts on the kidneys to regulate sodium ion concentration of the extracellullar fluid (ECF) is:
A) ADH
B) renin
C) secretin
D) aldosterone
E) epinephrine

D) aldosterone

Antidiuretic hormone prevents excessive water loss by promoting water reabsorption in the:
A) glomerulus
B) proximal convoluted tubule
C) distal convoluted tubule
D) collecting duct
E) bladder

D) collecting duct

A simple rule concerning water and electrolyte regulation is:
A) salt passively follows water
B) salt actively follows water
C) potassium passively follows sodium
D) water passively follows salt
E) water actively follows salt

D) water passively follows salt

The results of the renin-angiotensin mechanism mediated by the juxtaglomerular apparatus of the renal tubules include all of the following EXCEPT:
A) vasoconstriction
B) increased peripheral resistance
C) blood volume increase
D) blood pressure increase
E) suppression of aldosterone

E) suppression of aldosterone

A blood pH of 7.4 is considered:
A) physiological acidosis
B) neutral
C) normal
D) alkosis
E) acidosis

C) normal

The chemical buffer system that includes carbonic acid and its salt, which ties up the H+ released by strong acids, is called the:
A) phosphate buffer system
B) protein buffer system
C) ionic buffer system
D) bicarbonate buffer system
E) carbonic buffer system

D) bicarbonate buffer system

Which of these chemicals dissociates completely and liberates all the hydrogen ions when dissolved in water:
A) strong acids
B) weak acids
C) neutral substances
D) weak bases
E) strong bases

A) strong acids

When carbon dioxide enters the blood from tissue cells, it is converted to __________ for transport within blood plasma.
A) sodium hydroxide
B) ammonia
C) carbonic anhydrase
D) bicarbonate ion
E) sodium bicarbonate

D) bicarbonate ion

When blood pH begins to rise, the respiratory control centers in the brain are:
A) accelerated
B) depressed
C) not effected
D) shut off
E) controlled by the kidneys

B) depressed

How does the respiratory system respond to blood that has become acidic:
A) secrete more hydrogen ions
B) breathing rate increases
C) reabsorb more bicarbonate ions
D) breathing rate decreases
E) breathing stops

B) breathing rate increases

The need to get up during the night to urinate is called:
A) hypospadias
B) frequency
C)Nocturia
D) urgency
E) glomerulonephritis

C)Nocturia

The degenerative condition in which blisterlike sacs (cysts) containing urine form on the kidneys and obstruct urine drainage is called:
A) cystitis
B) dysuria
C) hypospadias
D) epispadias
E) polycystic kidney

E) polycystic kidney

Hypospadias is a condition of male children that involves:
A) atrophied prostate
B) opening of the urethra on the ventral surface of the penis
C) cysts on the kidneys
D) closing of the foreskin over the end of the penis
E) inflammation of the glomerulus

B) opening of the urethra on the ventral surface of the penis

The average output of urine for a normal healthy adult is:
A) 500 mL/day
B) 1000 mL/day
C) 1500 mL/day
D) 2000 mL/day
E) 2500 mL/day

C) 1500 mL/day

Control of the voluntary urethral sphincter in normal children is related to:
A) intelligence
B)nervous system developement
C) enzymatic regulation
D) hormone regulation
E) muscular development

B)nervous system developement

From childhood through late middle age, one of the most common bacteria to infect and inflame the urinary tract and cause urethritis and cystitis is:
A) streptococcus
B) staphylococcus
C) Escherichia coli
D) Mycobacterium tuberculosis
E) Clostridium botulinum

C) Escherichia coli

True or False
The kidneys are situated in a retroperitoneal position and found between the T12 and L3 vertebrae.

TRUE

True or False
The tiny filtering structures of the kidneys are called nephrons.

TRUE

True or False
The lumen surfaces of the tubule cells within the proximal convoluted tubule are covered with microvilli.

TRUE

True or False
The region of the renal tubule closest to the glomerular capsule is the distal convoluted tubule.

FALSE

True or False
The peritubular capillary bed arises from the afferent arteriole.

FALSE

True or False
Blood proteins and blood cells are too large to pass through the filtration membrane and should not be found in filtrate.

TRUE

True or False
Tubular reabsorption begins in the glomerulus.

FALSE

True or False
Most reabsorption occurs in the proximal convoluted tubule of the nephron.

TRUE

True or False
The pigment that gives urine its characteristic yellow color is urochrome.

TRUE

True or False
A diet rich in proteins such as eggs, cheese, and whole-wheat products produces urine with an alkaline pH.

FALSE

True or False
Tubular secretion, which seems to be important for removal of substances not already in the filtrate, is essentially reabsorption in reverse.

TRUE

True or False
Urine moves down the ureters into the bladder due to gravitational pull alone.

FALSE

True or False
The internal urethral sphincter is involuntary.

TRUE

True or False
The urethra, which carries urine exiting the bladder by peristalsis, is typically shorter in females than in males.

TRUE

True or False
The involuntary internal urethral sphincter is composed of skeletal muscle.

FALSE

True or False
The fluid stored inside cells is referred to as extracellular fluid (ECF).

FALSE

True or False
Excess blood plasma in the bloodstream initiates the thirst mechanism to restore fluid balance.

FALSE

True or False
Antidiuretic hormone (ADH) causes increased water loss through the urine.

FALSE

True or False
The most important trigger for aldosterone release is the renin-angiotensin mechanism, mediated by the renal tubules.

TRUE

True or False
A person with arterial blood pH above 7.45 is said to have acidosis.

FALSE

True or False
Carbon dioxide is most commonly transported as the bicarbonate ion in the blood.

TRUE

True or False
When blood pH becomes too acidic, the tubule cells of the kidneys excrete bicarbonate ions and retain hydrogen ions.

FALSE

True or False
Sexually transmitted infections (STIs) are primarily infections of the reproductive tracts but may also cause urinary tract infections.

TRUE

True or False
Incontinence is often the final outcome of the urinary system during the aging process.

TRUE

Fluid passes from the blood into the glomerular capsule of the nephron

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

A) glomerular filtration

Needed substances are moved from the filtrate back into the blood

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

B) tubular reabsorption

Aldosterone promotes sodium and thus water to move from the filtrate through the tubule cells into the blood

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

B) tubular reabsorption

Antidiuretic hormone (ADH) promotes the movement of water from the filtrate back into the blood of the peritubular capillaries

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

B) tubular reabsorption

Substances are moved from the blood of the peritubular capillaries into the filtrate

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

C) tubular secretion

Urine is produced during this process

A) glomerular filtration
B) tubular reabsorption
C) tubular secretion

C) tubular secretion

Cup-shaped extensions of the pelvis

A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

B) calyces

Outer, lighter region of the kidney

A) renal cortex
B)calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

A) renal cortex

Vessels supplying each kidney with blood to be filtered

A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

E) renal artery

Cortex-like extensions that separate the pyramids

A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

I) renal columns

Darker, reddish-brown internal area of the kidney
A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

H) renal medulla

Triangular regions with a striped appearance
A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

C) renal pyramids

Flat, basinlike cavity medial to the hilus of the kidney
A) renal cortex
B) calyces
C) renal pyramids
D) renal vein
E) renal artery
F) pyramids
G) renal pelvis
H) renal medulla
I) renal columns

G) renal pelvis

Tube that drains urine from the kidney to the bladder
A) bladder
B) ureter
C) urethra

B) ureter

Muscular sac suitable for temporary urine storage
A) bladder
B) ureter
C) urethra

A) bladder

Transports urine and sperm in males

A) bladder
B) ureter
C) urethra

C) urethra

In males, this organ is surrounded by the prostate
A) bladder
B) ureter
C) urethra

A) bladder

Contains an area called the trigone formed by the openings of the ureters and urethra
A) bladder
B) ureter
C) urethra

A) bladder

Inflammation of this organ is called cystitis

A) bladder
B) ureter
C) urethra

A) bladder

Identify and describe the three major processes involved in urine formation.

Glomerular filtration is a nonselective, passive process with the glomerulus acting as the filter. The filtrate formed is essentially blood plasma without blood proteins, which are too large to pass through the filtration membrane into the renal tubule. Tubular reabsorption is the process by which the body reclaims substances within the filtrate that it wants to keep. Most reabsorption is an active process using membrane carriers. Substances that are typically reabsorbed include amino acids, glucose, and ions. Most reabsorption occurs in the proximal convoluted tubules. Tubular secretion is the opposite process. With secretion, substances such as hydrogen ions, potassium ions, and creatinine are removed from the peritubular capillaries into the tubules to be eliminated in urine.

Describe the normal characteristics of freshly-voided urine in a healthy adult.

Urine is a pale, straw-colored liquid that progressively becomes a darker yellow color as it becomes more concentrated. The yellow color is a result of the presence of urochrome pigment, a by-product of hemoglobin breakdown. Urine is more dense than water with a specific gravity of 1.001 to l.035. Urine is sterile and slightly aromatic and has an acidic pH of around 6. Urine normally contains sodium and potassium ions, urea, uric acid, creatinine, ammonia, and bicarbonate ions, as well as other ions the body needs to dispose of.

Trace the pathway of a red blood cell through the kidney from the renal artery to the renal vein.

Red blood cells are not filtered by the glomerulus since they are too large to pass through the filtration membrane. Instead, red blood cells travel through the renal artery, segmental artery, interlobar artery, arcuate artery, cortical radiate artery, afferent arteriole, glomerulus, and on to the efferent arteriole. Then, the red blood cell continues its travels to the peritubular capillaries and exits the kidney via the cortical radiate vein, arcuate vein, interlobar vein, and the renal vein.

Contrast the roles of the ureters and urethra in the urinary system.

The ureters are tubes that connect the kidneys to the bladder. Each ureter transports urine to the bladder. Both gravity and peristalsis aid in the movement of urine. The urethra is a tube that transports urine from the bladder to the outside of the body. The passage of urine from the bladder into the urethra is controlled by two sphincters: the internal, involuntary sphincter and the external, voluntary sphincter.

Explain the renin-angiotensin mechanism.

The renin-angiotensin mechanism is the most important trigger for the release of aldosterone. It is mediated by the juxtaglomerular (JG) apparatus of the renal tubules. The JG apparatus consists of modified smooth muscle cells that are stimulated by low blood pressure within the afferent arteriole or changes in solute content of the filtrate. The JG cells respond to these changes by releasing renin into the blood. Renin catalyzes reactions that lead to angiotensin II production, which then acts directly on the blood vessels to cause vasoconstriction as well as aldosterone release. Aldosterone then causes the reabsorption of sodium and water, leading to increased blood volume and blood pressure.

Explain how antidiuretic hormone (ADH) compensates for blood that contains too many solutes.

Osmoreceptors in the hypothalamus react to changes in blood composition, such as less water and too many solutes. The posterior pituitary is alerted to release antidiuretic hormone (ADH) which travels through the blood to its target organ, the kidney. In the kidney, the collecting ducts respond to ADH by reabsorbing more water. As a result, more water returns to the blood while small amounts of concentrated urine are formed. ADH is released and additional water is reabsorbed from the filtrate until blood solute concentration returns to normal.

what is abnormal backflow of urine fro the bladder to the ureter ccalled

vesicoureteral reflux

which term best describes a distention of the renal pelvis and calyces due to urine that cannot exit into the ureters

hydronephrosis

what is inflammation of the urinary bladder called

cysitis

selet the term that describes a hereditary disorder in which grapelike sacs replace normal kidney tissue

polycystic kidney disease

what is shunting the blood so that is may be filtered known us

dialysis

what is another way of describing the renal calcui

nephrolithiasis

what is a inability to empty the urinary bladder

urinary retention

what is the inability to control the urinary bladder called

urinary incontinence

which term best describes an inflammation of the renal pelvis

pyelonephritis

what is the medical term for urteral stricture

ureterostenosis

what is herniation of the urinary bladder into the vagina called

vesicocele

what is the removal of toxins in blood called

filtration

what is returning water electrolytes and nutrition to the bloodstream called

reabsortion

what is the release of urine from the urinary bladder called

micturiction

what is the term that is synonymous for albuminuria

proteinuria

which term best decribes the specific filtration structur of the urinary system

glomerulus

select the uriary structure that is most closely associated with reabsorbtion of water elctolytes and nutrients

nephron

renal tubulues empty urine into the

renal pelvis

where are glomeruli located?

renal cortex

what is the functional unit of the kidney called

nephron

which of the following terms mean the presence in the urine of abnormally large quantities of protein usually albumin

albuminuria

which of the following term means painful urination

dysuria

which of the following terms means a condition of urinary incontinence sepeciallly aat night in the bed bedwetting

enuresis

which of the following terms means sercetion of a diminished amount of urine in relation of the fluid intake scanty urine output

oliguria

which of the following term means the presence of pus in the urine

pyuria

directs urine to the urinary bladder

ureter

temporary reservoir for urine

urinary bladder

directs urine out of the bladder

urethra

filter blood produce urine

kidneys

directs blood into the kidney

renal artery

takes blood out of the kidney

renal vein

collects urine from the tubules

calyx

diabetes is often often associated with __ the excretion of abnormally large amounts of urine

polyurine

the presence of pus in the urine is known as

pyuria

__ is defined as diminished urine secretion

oliguria

bowmans capsule is also called

glomerial capsal

___ is accomplished by inserting a tube through the uretha into the urinary bladder

catherilization

a urinary tract infection is associated with __ whis blood in the urine

hematuria

___ is the visual examination of the urinary bladder

systopy

essive urination at night is called

nocturia

the _ is a solution that draws fluid and toxins from the blood and across the peritoneal membrane

dialysate

a ___ is the physiscal chemical or microsopic examintaion of the urine

urinaylisis

vcug

voiding cystoourethogram

crf

chronic renal failure

agn

acute glomerular nephritis

ESRD

end stage enal failure diesease

uti

urinary tract infection

gfr

glomerular filtration rate

capd

continous ambulatory peritonal dialysis

ccpd

continous cycling pperitoneal dialysis

kub

kidney urethra and ureters

one of pair tubes that carries urine from the kidney to the bladder

ureter

the kidneys help regulate ____________ by producing renin

blood pressure

renin

enzyme secreted by the kidneys catalyzes the formation of angiotensin and thus affects blood pressure

the ___________ process internal garbage, allowing wastes and excess ions to leave the body in urine

kidneys

kidney hormone _____________ stimulates red blood cell production in bone marrow

erythropoetin

What vitamin do the kidneys convert to it’s active form

vitamin D

Where structures such as the ureters, renal blood vessels and nerves enter or exit the kidney

renal hilum

What encloses the kidney and gives it a glistening appearance

fibrous capsule

The fatty mass that surrounds the kidney and protects it from blows

perirenal fat capsule

This outermost capsule on the kidney, anchors it and helps hold it in place

renal fascia

What are the three distinct regions that can be noted when a kidney is cut lengthwise?

renal cortex, renal medulla, and renal pelvis

Blood goes into the kidney through the ___________

renal artery

Purified blood goes out of the kidney through the _____________

renal vein

_____________ are the structural and functional units of the kidneys; responsible for forming urine

nephrons

What are the two main structures of nephrons?

glomerulus and renal tubule

The knot of capillaries on the nephron is ____________.

glomerulus

The portion of the renal tubule that is enlarged and cup shaped and completely surrounds the glomerulus.

Bowman’s capsule

Where the renal tubule ends

collecting duct

The order of the renal tubule from the glomerular capsule

proximal convoluted tubule->loop of henle-.distal convoluted tubule

Each of these receives urine from many nephrons

collecting ducts

Where the collecting ducts deliver the final urine product into

calyces and renal pelvis

Each nephron is associated with two capillary beds which are _______________

glomerulus and peri-tubular capillary bed

"feeder vessel" that is larger and feeds the glomerulus

afferent arteriole

receives blood that has passed through the glomerulus

efferent arteriole

blood pressure in the glomerular capilaries is much __________ than in other capillary beds

higher

low pressure capillaries that are adapted for absorbtion and arise from the efferent arteriole that drains the glomerulus

peri-tubular capillaries

Urine formation is the result of what three processes?

glomerular filtration, tubular reabsorbtion, and tubular secretion

________________ is a nonselective, passive process in which fluid passes from the blood into the glomerular capsule part of the renal tubule

glomerular filtration

Once in the capsule, the fluid is called filtrate and is essentially what?

plasma without blood proteins

When either one of these appear in the urine, it is a fair bet that there is a problem with the glomerular filters

proteins and blood cells

When this drops too low, glomerular pressure becomes inadequate to force substances out of the blood into the tubules.

arterial blood pressure

abnormally low urinary output

oliguria

less than 100mL/day urine output

anuria

____________ begins as soon as the filtrate enters the proximal convoluted tubule

tubular reabsorption

These are poorly absorbed, if at all

Nitrogenous waste products

formed by the liver, this is excreted in urine at the end of protein synthesis

urea

this is released in urine when nucleic acids are metabolized, and can cause someone to get kidney stones

uric acid

excreted in urine and associated with creatine metabolism

creatnine

tubular reabsorbtion in reverse

tubular secretion

Filtrate contains everything that blood plasma does except ______________

proteins

____________ contains nitrogenous wastes and unneeded substances

urine

The normal yellow color of urine is from, _____________, a pigment that results from the body’s destruction of hemoglobin

urochrome

the term to compare how much heavier urine is than distilled water is what?

specific gravity

the specific gravity of urine

1.001-1.035

What substance are normally not found in urine

glucose, blood proteins, red blood cells, hemoglobin, white blood cells and bile

two slender tubes each 25-30cm each

ureters

smooth muscle layers in the ureters walls contract to propel urine into the bladder by ___________

peristalsis

This is a smooth, collapsible, muscular sac that stores urine temporarily

urinary bladder

The three openings of the bladder

two ureter openings and the single opening of the urethra

The smooth triangular region of the bladder base outlines by three openings

trigone

in males this surrounds the neck of the bladder where it empties into the urethra

prostate

the three layers of smooth muscle in the bladder are collectively called

detrusor muscle

the mucosa in the bladder is called

transitional epithelium

A moderatley full bladder holds how much urine?

500ml, but can hold twice that amount

a thin walled tube that carries urine by peristalsis from the bladder to the outside of the body

urethra

the two functions of the urethra in males

carry urine outside the body and passageway for sperm

another word for voiding or urination or voiding

micturition

four major roles of the kidneys

1 excretion of nitrogen containing wastes, 2 maintaining water and electrolyte balance, 3 electrolyte balance of the blood, and 4 ensuring proper blood pH

very small changes in the _______________ in the various fluid compartments cause water to move from one compartment to another

solute concentrations

the driving force for water intake

thirst mechanism

what routes does water leave the body

vaporizes out of the lungs, perspiration and the stool

the highly sensitive cells in the hypothalamus that attribute to the release of ADH

osmo-receptors

when ADH is not released leading to the release of large amounts of dilute urine

diabetes insipidus

two hormones attributing to kidneys

ADH and aldosterone

the electrolyte most responsible for osmotic water flows

sodium ion (Na+)

what the renin-angiotensin mechanism is mediated by

juxtaglomerular apparatus

juxtaglomerular apparatus

specialized tissue that releases the enzyme renin when blood pressure or blood volume drops in the afferent arteriole that supplies blood to the glomerulus

For the cells to function properly, blood pH must be

between 7.35-7.45

arterial blood pH above 7.5

alkalosis

arterial blood pH below 7.35

acidosis

any arterial pH between 7.35 and 7.0

physiological acidosis

what is the acid-base balanced by?

kidneys

The three major chemical buffer systems

bicarbonate, phosphate, and protein buffer systems

urine pH

4.5-8.0

degenerative disease with family history, where kidneys are enlarged and have blisterlike sacs containing urine; obstruct urine drainage

polycystic kidney

condition occuring only in male babies; urethral orfice is located on ventral surface of penis

hypospadias

common cause of bacterial infections of the urinary tract

e. coli

some effects of aging on the bladder

urgency, frequency, nocturia, dysuria

dysuria

painful or difficult urination

Put in Correct Order:

Loop of Henle
Bowman’s Capsule
Proximal Convoluted Tubule
Collecting Tubules
Distal Convoluted Tubule

1. Bowman’s Capsule 2. Proximal Convoluted Tubule 3. Loop of Henle 4. Distal Convoluted Tubule 5. Collecting Tubules

gives the pyramids their striped appearance

Collecting ducts/tubules

which kidney is lower than the other, and why?

right is slightly lower than the left, because of the liver.

Pyelonephritis

An inflammation of the kidney pelvis and surrounding kidney tissues.

Stores urine temporarily

urinary bladder

Produces urine

kidneys

Carries urine from the body.

urethra

Carries urine from the kidneys

ureters

Maintains composition and volume of
body fluids.

kidneys

Outer layer containing renal corpuscles

cortex

Region containing renal pyramids

medulla

Flattened cavity continuous with ureter

pelvis

Receptacles surrounding renal papillae

calyces

Thin layer of connective tissue enveloping
kidney

renal capsule

Arterial capillaries in renal corpuscle

glomerulus

Functional units of the kidneys

nephrons

U-shaped portion of renal tubule

loop of Henle

Part of renal tubule joined to glomerular capsule.

proximal convoluted tubule

Part of renal tubule joined to a collecting duct

distal convoluted tubule

Formed of modified cells at point of contact of
distal tubule and afferent arteriole

juxta-glomerular apparatus

Passage of water and solutes from glomerulus
into glomerular capsule

filtration

Plasma component that cannot pass through
glomerular pores

proteins

the force that produces filtration

glomerular blood pressure

Fluid in glomerular capsule

filtrate

Recovery of needed materials from filtrate into
the blood.

tubular reabsorption

Volume of filtrate formed per day.

180 liters

Method of transport of sodium ions

mostly active transport

Method of transport of water.

osmosis

Method of transport of glucose.

active transport

Substance reabsorbed that concentrates the
urine.

water

Passage of substances from blood into the
filtrate.

tubular secretion

Indicate whether each statement is true (T) or false (F).

Urine contains waste and excessive materials removed from the blood.

true

Indicate whether each statement is true (T) or false (F).

Urine formation depends upon maintenance of the blood pressure within the glomeruli.

true

Indicate whether each statement is true (T) or false (F).

Negatively charged ions and positively charged ions are electrochemically attracted to each other

true

Hormone promoting water reabsorption

anti-diuretic hormone

Hormone promoting reabsorption of Na+

aldosterone

Hormone promoting secretion of K+

aldosterone

Three nitrogenous wastes in urine

urea uric acid creatinine

Which of the following is NOT an organ found in the urinary system:
A) kidney
B) ureter
C) pancreas
D) urinary bladder
E) urethra

C) pancreas

The enlarged, cup-shaped closed end of the renal tubule that completely surrounds the glomerulus is called the:
A) collecting duct
B) proximal convoluted tubule
C) loop of Henle
D) Bowman’s capsule
E) distal convoluted tubule

D) Bowman’s capsule

The portion of the renal tubule that completely surrounds the glomerulus is the:
A) collecting duct
B) proximal convoluted tubule (PCT)
C) glomerular (Bowman’s) capsule
D) distal convoluted tubule (DCT)
E) loop of Henle

C) glomerular (Bowman’s) capsule

The peritubular capillaries arise from the __________, which drains the glomerulus.
A) afferent arteriole
B) efferent arteriole
C) Bowman’s capsule
D) loop of Henle
E) glomerulus

B) efferent arteriole

The tube connecting the renal hilus of the kidney to the bladder is the:
A) urethra
B) proximal convoluted tubule
C) distal convoluted tubule
D) ureter
E) collecting duct

D) ureter

The noninvasive treatment for kidney stones that uses ultrasound waves to shatter calculi is called:
A) lithotripsy
B) lithiasis
C) lithectomy
D) lithotomy
E) lithoscopy

A) lithotripsy

The bladder is able to expand as urine accumulates within it due to the presence of:
A) rugae
B) transitional epithelium
C) segmentation
D) pseudostratified epithelium
E) sphincters

B) transitional epithelium

The average adult bladder is moderately full with __________ of urine within it.
A) 100 mL
B) 500 mL
C) 1 liter
D) 2 liters
E) 1 gallon

B) 500 mL

In a healthy young adult female, water accounts for:
A) one-quarter of body weight
B) less than one-half of body weight
C) approximately one-half of body weight
D) three-quarters of body weight
E) 99% of body weight

C) approximately one-half of body weight

The proper pH for the blood is:
A) 6.8-6.9
B) 7.0-7.35
C) 7.35-7.45
D) 7.5-8.0
E) 6.5-8.0

C) 7.35-7.45

The most potent of all mechanisms and substances that the body uses to regulate blood pH are:
A) the respiratory system controls
B) the kidneys
C) hormones
D) the buffer system
E) enzymes

B) the kidneys

In contrasting urine and filtrate by the time it reaches the collecting ducts, it could be said that:

filtrate contains almost everything that blood plasma does

The most potent of all mechanisms and substances that the body uses to regulate blood pH are:

the kidneys

Which one of the following terms describes the location of the kidneys:

retroperitoneal

The chemical buffer system that includes carbonic acid and its salt, which ties up H+ released:

bicarbonate buffer system

Functional kidneys develop within the womb by the third month after conception from the ________ set of tubule system.

third

The degenerative condition in which blisterlike sacs (cysts) containing urine form on the kidneys and obstruct urine drainage is called:

polycystic kidney

The enlarged, cup-shaped closed end of the renal tubule that completely surrounds the glomerulus is called the:

Bowman’s capsule

Of the capillary beds associated with each nephron, the one that is both fed and drained by arterioles is the:

glomerulus

Enlargement of the prostate that surrounds the neck of the bladder in adult men is called _________, which may cause voiding difficulty:

hyperplasia

Which one of the following is NOT a substance typically reabsorbed by the tubules under normal healthy conditions:

urea

Which one of the following is NOT true of urine under normal healthy conditions:

it is slightly alkaline

Which one of the following substances is normally found in urine:

creatine

In one 24-hour period, the kidneys of an average-sized healthy adult filter approximately ______ through their glomeruli into the tubules.

150-180 liters of blood plasma

Antidiuretic hormone prevents excessive water loss by promoting water reabsorption in the:

collecting duct

Urine is transported from the bladder to the outside of the body by the:

urethra

The triangular regions of the kidneys that are striped in appearance and separated by the renal columns are the:

renal pyramids

The noninvasive treatment for kidney stones that uses ultrasound waves to shatter calculi is called:

lithotripsy

Which one of the following is NOT one of the major roles of the kidneys in normal healthy adults:

conversion of ammonia to bicarbonate ion

The percentage of filtrate eventually reabsorbed into the bloodstream is closest to:

99%

Which one of the following is NOT one of the functions of the kidneys:

produce hormones that assist in digestion

The bladder is able to expand as urine accumulates within it due to the presence of:

transitional epithelium

The portion of the renal tubule that completely surrounds the glomerulus is the:

glomerular (Bowman’s) capsule

Control of the voluntary urethral sphincter in normal children is related to:

nervous system development

Uric acid, a nitrogenous waste product, results from the metabolism of:

nucleic acids

When blood pH begins to rise, the respiratory control centers in the brain are:

depressed

A simple rule concerning water and electrolyte regulation is:

water passively follows salt

The peritubular capillaries arise from the ________, which drains the glomerulus.

efferent arteriole

The nonselective, passive process performed by the glomerulus that forms blood plasma without blood protein is called:

filtration

Hypospadias is a condition of male children that involves:

opening of the urethra on the ventral surface of the penis

The average adult bladder is moderately full with ______ of urine within it.

500 mL

Each kidney contains about:

1 million nephrons

The chemically buffered combination of strong acids that dissociate completely in water with weak bases such as hydroxides leads to a:

weak acid and salt

Which one of the following is NOT true of incontinence:

it is never considered normal

The main hormone that acts on the kidneys to regulate sodium ion concentration of the extrracellular fluid (ECF) is:

aldosterone

Extracellular fluid is found everywhere in the body except:

within living cells

The process of emptying the bladder is referred to as voiding or:

micturition

The proper pH for blood is:

7.35-7.45

Which of the following is NOT an organ found in the urinary system:

pancreas

The results of the renin-angiotensin mechanism mediated by the juxtaglomerular apparatus of the renal tubules include all of the following EXCEPT:

suppression of aldosterone

When carbon dioxide enters the blood from tissue cells, it is converted to __________ for transport withing the blood plasma

bicarbonate ion

The tube connecting the renal hilus of the the kidney to the bladder is the:

ureter

The presence of pus in the urine is called:

pyuria

From childhood through the late middle age, one of the most common bacteria to infect and inflame the urinary tract and cause urethritis and cystitis is:

Escherichia coli

The kidneys are aided in the excretion of fluids by the:

lungs and skin

Most nephrons are located within the renal:

cortex

In a healthy young adult female, water accounts for:

approximately one-half of body weight

The voluntary controlled sphincter fashioned by skeletal muscle at the point where the urethra passes through the pelvic floor is called the:

external urethral sphincter

Dilute urine would have a specific gravity closest to:

1.001

Starting from the glomerular capsule, the correct order of the renal tubule region is:

proximal convoluted tubule, loop of Henle, distal convoluted tubule

The average output of urine for a normal healthy adult is:

1500 mL

As venous blood is drained from the kidney, which path does it follow:

cortical radiate veins, arcuate veins, interlobal veins, renal vein (CAIR)

sexually transmitted diseases (STDs) are primarily infections of the reproductive tracts but may also cause urinary tract infections

True

The lumen surfaces of the tubule cells within the proximal convoluted tubule are covered with microvilli

True

Incontinence is often the final outcome of the urinary system during the aging process

True

Following the micturition reflex, it is impossible to postpone bladder emptying

False

Nitrogenous waste products such as urea, uric acid, and creatinine are excreted from the body in urine rather than reabsorbed

True

The fluid stored inside cells is referred to as extracellular fluid (ECF)

False

Antidiuretic hormone (ADH) causes increased water loss through the urine

False

The specific gravity of urine is typically lower than specific gravity of pure water.

False

A person with arterial blood pH above 7.45 is said to have acidosis

False

The medial indentation of the kidney where several structures such as the ureters, renal blood vessels, and nerves enter and exit the kidney is called the hilus

True

Urine moves down the ureters into the bladder due to gravitational pull alone

False

The tiny filtering structures of the kidneys are called nephrons

True

When blood pH becomes too acidic, the tubule cells of the kidneys excrete bicarbonate ions and retain hydrogen ions

False

Blood proteins and blood cells are too large to pass through the filtration membrane and should not be found in filtrate

True

The movement of water from one fluid compartment to another has no effect on blood volume and blood pressure

False

The urethra, which carries urine exiting the bladder by peristalsis, is typically shorter in females than in males

True

The region of the renal tubule closest to the glomerular capsule is the distal convoluted tubule

False

The internal urethral sphincter is involuntary

True

Tubular secretion, which seems to be important for removal of substances not already in the filtrate, is essentially reabsorption in reverse

True

The pigment that gives urine its characteristic yellow color is urochrome

True

The peritubular capillary bed arises from the afferent arteriole.

False

The most important trigger for aldosterone release is the renin-angiotensin mechanism, mediated by the renal tubules

True

The kidneys help maintain acid-base balance of the blood by excreting bicarbonate ions

True

Tubular reabsorption begins in the glomerulus

False

Kidney

Renal hilum

Renal artery

Urinary bladder

Renal vein

Using the figure, identify the following:

A calyx is indicated by ________.

Lable A

Using the figure, identify the following:

The renal cortex is indicated by ________.

Label G

Using the figure, identify the following:

The glomerular capsule (Bowman’s capsule) is indicated by ________.

Label A

Using the figure, identify the following:

The efferent arteriole is indicated by ________.

Label C

Which one of the following terms describes the location of the kidneys?

retroperitoneal

The structural and functional units of the kidney are the renal (medullary) pyramids. (T/F)

false

The lumen surfaces of the tubule cells within the proximal convoluted tubule are covered with microvilli. (T/F)

true

The region of the renal tubule closest to the glomerular capsule is the distal convoluted tubule. (T/F)

false

The peritubular capillary bed arises from the afferent arteriole. (T/F)

false

Blood proteins and blood cells are too large to pass through the filtration membrane and should not be found in filtrate. (T/F)

true

Tubular reabsorption begins in the glomerulus. (T/F)

false

Most reabsorption occurs in the proximal convoluted tubule of the nephron. (T/F)

true

Tubular secretion moves items from the blood of the peritubular capillaries to the filtrate for elimination in the urine. (T/F)

true

A diet rich in proteins such as eggs, cheese, and whole-wheat products produces urine with an alkaline pH. (T/F)

false

Urine has a specific gravity closest to 1.001 when excessive fluids are consumed. (T/F)

true

Urine may routinely contain sodium, potassium, proteins, and red blood cells. (T/F)

false

renal cortex

renal medulla

renal columns

minor calyx

renal pyramid

internal urethral sphincter

ureter

external urethral orifice

external urethral sphincter

trigone of bladder

urethra

Which of these must you consciously relax for micturition to occur?

external urethral sphincter

Urine moves down the ureters into the urinary bladder due to gravitational pull alone. (T/F)

false

The urethra, which carries urine exiting the urinary bladder by peristalsis, is typically shorter in females than in males. (T/F)

true

The involuntary internal urethral sphincter is composed of skeletal muscle. (T/F)

false

The fluid stored inside cells is referred to as extracellular fluid (ECF). (T/F)

false

Excess blood plasma in the bloodstream initiates the thirst mechanism to restore fluid balance. (T/F)

false

Antidiuretic hormone (ADH) causes increased water loss through the urine. (T/F)

false

The most important trigger for aldosterone release is the renin-angiotensin mechanism, mediated by the renal tubules. (T/F)

true

Blood buffers are important in maintaining blood pressure. (T/F)

false

The bicarbonate buffer system prevents changes in blood pH through the action of carbonic acid and its salt, sodium bicarbonate. (T/F)

true

When blood pH becomes too acidic, the tubule cells of the kidneys excrete bicarbonate ions and retain hydrogen ions. (T/F)

false

Sexually transmitted infections (STIs) are primarily infections of the reproductive tracts but may also cause urinary tract infections. (T/F)

true

Incontinence is often the final outcome of the urinary system during the aging process. (T/F)

true

Pertubular capillaries

…

Efferent arteriole

…

Afferent arteriole

…

Blood Flow in Kidneys

1. Aorta 2. Renal Artery 3. Segmental artery 4. Interlobar artery 5. Arcuate artery 6. Cortical radiate artery 7. Afferent arteriole 8. Glomerulus 9. Efferent arteriole 10. Peritubular capillaries 11. Cortical radiate vein 12. Arcuate vein 13. interlobar vein 14. renal vein 15. inferior vena cava

The uptake of substances from the renal tubules of the nephrons is known as __________.

tubular reabsorption

The color of normal urine is attributed to a pigment resulting from the destruction of __________.

Hemoglobin

The term used to describe how much heavier urine is than distilled water is __________ gravity.

specific

Which of the following terms refers to an inflammation of the urinary bladder?

Cystitis

The triangular regions in the medulla of the kidney are called renal __________.

pyramids

This structure carries urine from the kidney to the bladder.

Ureter

What enzyme produced by the kidneys helps to regulate blood pressure?

Renin

Which of the following substances is/are not normally found in urine, and thus, if present, suggests a problem?

Red blood cells

Starting at the apex of a medullary pyramid, which is the correct sequence of structures through which urine flows to reach the exterior of the body?

Calyx, renal pelvis, ureter, urinary bladder, urethra

A fat mass called the __________ fat capsule surrounds each healthy kidney, providing protective cushioning.

perirenal

What is the most superficial region of the kidney?

Renal cortex

Which of the following terms refers to the formation of a large volume of urine?

Polyuria

All of the following are organs of the urinary system EXCEPT the __________.

Adrenals

Urine formation requires which of the following?

Glomerular filtration, tubular reabsorption, and tubular secretion

Which of the following is normally present in the filtrate forced from the glomerular capillaries but not normally present in the urine?

Glucose

What enzyme produced by the kidneys helps to regulate blood pressure?

Renin

Indicate the correct order in which the filtrate flows through the following structures of the nephron.

Glomerular capsule, PCT, loop of Henle, DCT, collecting duct

What are the structural and functional units of the kidneys that are involved in forming urine?

Nephrons

hat enzyme produced by the kidneys helps to regulate blood pressure?

…

The bladder wall contains three layers of smooth muscle, collectively known as the __________, and its mucosa consists of __________.

detrusor muscle; transitional epithelium

Kidney stones are also called __________

renal calculi

Blood leaving an afferent arteriole would enter which of the following?

Glomerulus

The nephron is responsible for __________ formation.

urine

ADH stimulates tubular reabsorption of __________.

water

Where does most reabsorption of substances from the glomerular filtrate occur?

In the proximal convoluted tubule

The smooth triangular region at the base of the bladder is called the __________.

trigone

Which of the following substances is/are NOT normally present in the filtrate?

proteins

Which of the following is NOT a correct description of the hilum of the kidney?

The hilum is on the most superior surface of the kidney

Which vessels absorb the solutes and water from the nephron?

peritubular capillaries

Which part of the nephron is involved in filtration?

glomerular capsule

Which part reabsorbs nutriention?

The proximal convoluted tubule

Which is the nitrogenous waste produced by the liver and poorly reabsorbed by the kidney?

Urea

What is the source of the yellow pigment urochrome?

hemoglobin

What part of the kidney attaches to the ureter?

renal pelvis

Which part of the nephron receives fluid from the glomerular capsular space?

proximal convoluted tubule

What part of a nephron is responsible for reabsorbing all the nutrients and most of the water?

proximal convoluted tubule (PCT)

Which of these is a nitrogenous waste associated with muscle tissue?

creatinine

What is one reason urinary tract infections are more common in females?

The female urethra is only 1.5 inches long.

What causes the internal urethral sphincter to open?

pressure from the contracting bladder

Which of the following conditions would result in oliguria?

low glomerular blood pressure

Which of these must you consciously relax for micturition to occur?

external urethral sphincter

Which fluid compartment contains the greatest fluid volume?

intracellular fluid (ICF)

What is the primary action of antidiuretic hormone?

It causes kidney-collecting ducts to reabsorb more water.

What is the mechanism of aldosterone?

It causes sodium reabsorption and potassium excretion.

Which of these is a major chemical buffer system of blood?

bicarbonate buffer system

Which of these describes polycystic kidney disease?

enlarged kidney with urine-filled, blisterlike sacs