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Which of the following substances is not normally found in filtrate? |
blood cells and large particles |
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What is the primary driving force (pressure) that produces glomerular filtration? |
hydrostatic pressure of blood (blood pressure) |
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Which substance would be found in higher concentration if the membrane were damaged? |
protein |
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If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease? |
net filtration would decrease |
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Calculate the net filtration pressure if capillary hydrostatic pressure is 60 mm Hg, capillary osmotic pressure is 25 mm Hg, and capsular hydrostatic pressure is 10 mm Hg |
25 mmHg |
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Approximately what percent of the total filtered volume is excreted as urine each day? |
less than 1% |
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Where does all filtration take place in the kidneys? |
glomerulus |
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Blood leaves the glomerulus via which vessel? |
efferent arteriole |
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If you know that the renal clearance of substance X is zero, which of the following can you say is true about how the kidney handles X? |
X is either not filtered or filtered and completely reabsorbed |
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Using what you know about renal handling of Na+, predict the renal clearance of Na+ |
clearance is less than the GFR |
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Which combination of changes would increase the glomerular filtration rate (GFR) the most? |
Vasodilation of the afferent arteriole and vasoconstriction of the efferent arteriole |
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What unique epithelial cells of Bowman’s capsule allow for the final stage of filtration? |
podocytes |
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Glomerular filtration rate is determined by the net filtration pressure and the filtration coefficient. Which two factors determine the filtration coefficient? |
glomerular surface area and the permeability of the filtration barrier |
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If all glucose is normally reabsorbed in the proximal tubule of the nephron, why do people with diabetes have glucose in their urine? |
The amount of glucose filtered is greater than the renal threshold |
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Secretion into the nephron is a/an ________ process because the direction is ________ the concentration gradient |
active; against |
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Why is inulin administration an effective way of measuring renal clearance rates? |
inulin is neither secreted nor reabsorbed |
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Which equation correctly describes the relationship between excretion, filtration, reabsorption, and secretion? |
excretion = filtration – reabsorption + secretion |
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Technically, the kidneys are located |
behind the peritoneal membrane |
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The process of filtration in the kidney is most accurately described as |
relatively nonspecific |
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When fluid flow through the distal tubule increases as a result of increased GFR, the macula densa cells send a chemical message to the neighboring afferent arteriole. The afferent arteriole constricts, increasing resistance and decreasing GFR. This type of autoregulation involving both the kidney tubule and the arteriole is known as ________ feedback |
tubuloglomerular |
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The ________ are the long peritubular capillaries that dip into the medulla |
vasa recta |
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Place the following blood vessels that carry blood to and within the kidney in the order in which blood passes through them. |
1, 3, 2, 4 |
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Measurements in a nephron reveal a glomerular hydraulic pressure of 69 mm Hg, and a fluid pressure in the Bowman’s capsule of 15 mm Hg. Assuming that the plasma osmotic pressure is 30 mm Hg, and that essentially no plasma proteins are filtered by the glomerulus, what is the net glomerular filtration pressure in this case? |
24 mmHg |
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In a normal kidney, which of the following conditions would cause an increase in the glomerular filtration rate (GFR)? |
decrease in the concentration of plasma proteins in the blood |
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Which part of the nephron is responsible for the greatest possible increase in urine concentration? |
collecting duct |
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Which word means to selectively move molecules from the blood and add them to the tubule lumen? |
secretion |
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In normal kidneys, blood cells and plasma proteins are |
not filtered |
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Contents in the peritubular capillaries are actively transported into proximal and distal convoluted tubules in a process known as |
secretion |
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In which process can glucose transport reach saturation? |
reabsorption |
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A patient has a genetic defect that decreases the number of GLUT transporters in the nephron tubule. Which would you expect? |
decreased transport max and increased glucose in urine |
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What happens if reabsorption of a substance increases (and filtration and secretion stay the same)? |
Decreased excretion of the substance and an increased amount of the substance in blood |
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In a diabetic patient with high blood sugar above transport maximum, which would you expect? |
There will be increased glucose in urine and increased glucose clearance |
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1. The first process in urine formation that pushes a fluid similar in composition to plasma into the renal tubule |
filtration |
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The movement of molecules from the tubule lumen into the peritubular capillaries |
reabsorption |
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The transfer of molecules from the extracellular fluid of the peritubular capillaries into the lumen of the nephron |
secretion |
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The elimination of urine from the body into the external environment |
excretion |
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Which of the following would best help a clinician understand how well the kidney was able to remove a substance from the body? |
clearance of the substance |
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Which of the following statements best describes clearance? |
the rate at which a solute disappears from the plasma by either excretion or metabolism |
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Which of the following variables must be known in order to calculate the clearance of a substance? |
concentration of solute in the plasma excretion rate of the substance |
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Clearance of X = |
excretion rate of X / plasma concentration of X |
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Clearance of a substance is less than the glomerular filtration rate |
net absorption |
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Clearance of the substance is the same as the glomerular filtration rate |
no net reabsorption or secretion |
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Clearance of the substance is greater than the glomerular filtration rate |
net secretion |
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What is Mrs. Adler’s glomerular filtration rate (rounded to the nearest liter)? |
126 L/day |
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How did Mrs. Adler’s kidneys handle QuikSmart? |
there has been a net secretion of QuikSmart |
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