|
what is the flow of blood through the blood vessels? |
heart->artery->capillary->vein ->valve ->heart |
|
list from most external to most deeper walls of the arteries and veins |
1. tunica externa 2. tunica media 3. tunica intima |
|
which of the walls of the arteries vs veins have different thickness in each? |
-tunica media is thicker than the tunica externa in arteries and that the opposite is true in veins (tunica externa is thicker than the tunica media) |
|
Which tunic of an artery is most responsible for maintaining blood pressure and continuous blood circulation? |
c. tunica media |
|
Which statement best describes arteries? |
c. All carry blood away from the heart. |
|
Which of the choices below explains why the arterioles are known as resistance vessels? |
a. The contraction and relaxation of the smooth muscle in their walls can change their diameter. |
|
The arteries that directly feed into the capillary beds are called ________. |
arterioles |
|
Permitting the exchange of nutrients and gases between the blood and tissue cells is the primary function of ________. |
d. capillaries |
|
Which of the following is not true regarding fenestrated capillaries? |
d. Fenestrated capillaries form the blood-brain barrier. |
|
Which of the following is true about veins? |
c. Veins are called capacitance vessels or blood reservoirs. |
|
which has valves: arteries vs veins? |
Veins have valves; arteries do not. |
|
Peripheral resistance ________. |
a. increases as blood viscosity increases |
|
The influence of blood vessel diameter on peripheral resistance is ________. |
b. significant because resistance is inversely proportional to the fourth power of the vessel radius |
|
The pulse pressure is ________. |
b. systolic pressure minus diastolic pressure |
|
Factors that aid venous return include all except ________. |
c. urinary output |
|
Arteriolar blood pressure increases in response to all but which of the following? |
b. falling blood volume |
|
How would an attack by a mugger effect blood pressure? What is the physiological basis for your answer? |
e. Blood pressure would increase due to sympathetic nervous system stimulation. |
|
Which of the following chemicals does not help regulate blood pressure? |
c. nitric acid |
|
Aldosterone will ________. |
d. promote an increase in blood pressure |
|
Mechanisms that do not help regulate blood pressure include ________ |
a. the dural sinus reflex |
|
The short-term controls of blood pressure, mediated by the nervous system and bloodborne chemicals, primarily operate via all but which of the following? |
b. altering blood volume |
|
The baroreceptors in the carotid sinus and aortic arch are sensitive to which of the following? |
a. changes in arterial pressure |
|
vascular shock |
normal blood volume but poor circulation due to extreme vasodilation |
|
cardiogenic shock |
results from heart inability to sustain adequate circulation due to myocardial damage |
|
circulatory shock |
due to inadequate blood flow to meet tissue needs |
|
hypovolemic shock |
due to large-scale of blood loss |
|
The velocity of blood flow is ________. |
c. slowest in the capillaries because the total cross-sectional area is the greatest |
|
what kind of system is the cardiovascular system? (open vs closed) |
closed system |
|
what are the 3 major types of vessels? |
-arteries -veins -capillaries |
|
in what direction the arteries carry blood? |
carry blood Away from the heart |
|
in what direction the veins carry blood? |
carry blood toward the heart |
|
where are capillaries located and what do? |
Capillaries contact tissue cells and directly serve cellular needs |
|
how people thought blood moved inside the body before the idea of blood circulating in pipes (vessels)? |
people thought that blood moved through the body like an ocean tide, first moving out from the heart and then ebbing back in the same vessels |
|
list blood vessels (5) |
-arteries -arterioles -capillaries -venules -veins |
|
what are arteries? |
strong, elastic vessels adopted for carrying high-pressure blood away from the heart |
|
leaving the heart, arteries become smaller as they divide and become_, which feed into_ |
-arterioles -capillary beds of body organs and tissues |
|
blood drains from the capillaries into_, and then into_ |
-venules -larger veins that ultimately empty into heart |
|
venules |
smallest veins |
|
list the succession of blood vessels as go through body and back to heart |
heart->artery->arterioles->capillaries (capillary bed)->venules->veins->heart |
|
arteries are said to_as they become arterioles. How this is different for veins? |
-branch, diverge, fork -veins are said to join, merge, and converge into successively large vessels |
|
what kind of blood it carries in systemic circulation: |
a. arteries carry oxygenated blood away form the heart b. veins carry deoxygenated (oxygen poor) blood toward the heart |
|
what kind of blood it carries in pulmonary circulation: |
a. arteries carry deoxygenated (oxygen poor) blood away from the heart to the lungs b. veins carry oxygen rich blood toward the heart from lungs |
|
how capillaries serve cellular needs? |
-exchanges between the blood and tissue cells occur primarily through the gossamer-thin capillary walls |
|
what is the general name of the layers of wall blood vessels? how many they have? these surround what? |
-tunics -3 tunics -they surround a central-blood containing space, the vessels lumen |
|
list the layers from innermost to most external in blood vessels |
tunica interna (intima) tunica media tunica externa |
|
tunica intima (what it is and where found) |
-innermost tunic or layer of the walls of blood vessels -In direct contact with blood of lumen |
|
what kind of tissue tunica intima contains? |
-endothelium, simplest squamous epithelium that lines the lumen of all vessels |
|
how the cells of endothelium are found with respect to each other? explain why is this |
its flat cells fit closely together, forming a slick surface that minimize friction as blood moves through lumen |
|
in vessels larger than 1mm, what tissue is found in them? |
-subendothelial layer that supports endothelium |
|
tunica media (layer, composed of what (2)) |
-the middle tunic or layer of walls of blood vessels -it is composed mostly of circularly arranged smooth muscle cells and sheets of elastin |
|
what controls tunica media? what does in response to this control? (2 activities) |
-the acitvity of its smooth muscle is regulated by sympathetic vasomotor nerve fibers of the ANS and a whole battery of chemicals -it either performs vasoconstriction or vasodilation |
|
vasoconstriction |
-lumen diameter decreases as the smooth muscle of tunica media contracts |
|
vasodilation |
lumen diameter increases as the smooth muscle of tunia media relaxes |
|
why the activity of tunica media is so important? |
-the activities of tunica media are critical in regulating circulatory dynamics because small changes in vessel diameter greatly influence blood flow and blood pressure |
|
the tunica media is_(thickness) in arteries, which bear the chief responsibility for_ (function) |
-bulkiest layer in arteries -maintaining blood pressure and circulation |
|
tunic externa (what it is, other name, what composes it and 2 functions) |
-the outermost layer of blood vessel wall -also called tunica adventitia -it is largely composed of loosely woven collagen fibers that protect and reinforce vessel, and anchor it to surrounding structures |
|
capillaries are made of_ |
endothelial cells |
|
describe the composition of the following: |
a. Endothelial layer b. Smooth muscle and elastic fiber layer c. collagen fibers |
|
what larger veins contain in their tunica externa? what it does? |
-vaso vasorum (vessels of the vessels) -nourish the more external tissues of the blood vessel wall |
|
which branch of the autonomic nervous system innervates blood vessels? which layer of the blood vessel wall do these nerves innervate? what are the effectors (cells that carry out the response)? |
-sympathetic nervous system innervates the tunica media. -the effector cells in the tunica media are smooth muscle cells |
|
when vascular smooth muscle contracts, what happens to the diameter of blood vessels? what is this called? |
when vascular smooth muscle contracts, the diameter of the blood vesssel becomes smaller. This is called vasoconstriction. |
|
in terms of relative size and function, arteries can be divided into 3 groups: |
-elastic arteries -muscular arteries -arterioles |
|
how differ tunics in arteries vs veins? |
-the tunica media is thicker than the tunica externa in arteries -the tunica externa is thicker than the tunica media in veins |
|
elastic arteries are also known as_ |
conducting arteries |
|
elastic arteries (thickness, where found, lumen size and what advantage this gives, all three tunics contain_, function) |
-Thick-walled arteries near the heart; – Large lumen, low-resistance -elastin in all three tunics -Withstand large blood pressure fluctuations |
|
examples of elastic arteries would be_ |
the aorta and its major branches |
|
elastic arteries are inactive at what ? (activity that they cannot do) |
at vasoconstriction |
|
elastic arteries are _reservoirs. why? |
-pressure reservoirs -because they expand and recoil as the heart ejects blood. consequently, blood flows fairly continuously rather than starting and stopping with the pulsating rhythm of the heartbeat |
|
what is artherosclerosis? |
-the hardening of the blood vessels -blood flows more intermittently. Pressure cannot be regulated because the walls cannot contract/relax to keep blood under pressure |
|
without the pressure-smoothing effect of the elastic arteries, what would be the pressure that other arteries would experience? what is the ultimate consequence of this? |
-the walls of arteries throughout the body experience higher pressures -the high pressures would eventually weaken the arteires and may balloon out or even burst |
|
after the heart we have what blood vessel? |
elastic arteries |
|
after elastic arteries, what kind of blood vessel is found? |
muscular arteries |
|
muscular arteries (location, and what do (2)) |
-distal to elastic arteries -deliver blood to body organs -Active in vasoconstriction |
|
describe composition of muscular arteries (focus on tunica media) |
thick tunica media, more smooth muscle and less elastic tissue |
|
arterioles (what are them, lead to what, and what do) |
-smallest arteries -lead to capillary beds -Control flow into capillary beds via vasodilation and constriction |
|
muscular arteries are also known as_because of its function |
distributing arteries |
|
arterioles are also known as_ |
resistance vessels |
|
which artery has the thickest tunica media of all vessels? |
muscular arteries |
|
the blood flow into capillary beds is determined by_(specific blood vessel feature) |
arteriole diameter |
|
explain how arteriole diameter affects and controls the deliver of blood into the tissues |
-when arterioles contract, the tissues served are largely bypassed -when arterioles dilate, blood flow into the local capillaries increases dramatically |
|
capillaries (what are them, describe composition of tunica interna and the reason for this) |
-smallest blood vessels -thin tunica interna, one cell thick -Allow only a single RBC to pass at a time |
|
There are three structural types of capillaries: |
-continuous -fenestrated -sinusoids |
|
at strategic locations along the outer surface of some capillaries are_(cell) |
-spider-shaped pericytes |
|
pericytes (what they are made of, what do (2)) |
-smooth muscle-like cells that stabilize the capillary wall and help control capillary permeability |
|
what is the role of capillaries? |
-their role is to exchange materials (gases, nutrients, hormones, and so on) between the blood and the intersitial fluid |
|
continuous capillaries (where found (2), how common?, structure of endothelium) |
-abundant in skin and muscles -most common -they are continuous in the sense that their endothelial cells are joined together by tight junctions, providing and uninterrupted lining |
|
intercellular clefts (where found, what are them, how large, what let pass through) |
-found in continuous capillaries -the junctions found in continuous capillaries are often incomplete and leave gaps of unjoined membrane called intercellular clefts -are large enough to allow limited passage of fluids and small solutes |
|
endothelial cells cytoplasm of continuous capillaries contains numerous_that ferry fluids across the capillary wall |
-pinocytotic vesicles |
|
the continuous capillaries in _(location in body) are unique. why? how this is called? |
-brain -there the thigh junctions of the continuous capillaries are complete and extend around the entire perimeter of the endothelial cells, constructing the basis of the blood brain barrier |
|
The wall of an artery consists of an inner endothelium layer, tunica ____________ (smooth muscle), and tunica __________________ (connective tissue). |
-media -externa |
|
Sympathetic impulses reduce the diameter of the blood vessels causing __________________; when these impulses are inhibited, the diameters of the vessels increase or ___________. |
-vasoconstriction -vasodilatation |
|
Capillaries are the smallest vessels, consisting only of a layer of _________________ through which substances are _ |
-endothelium -exchanged with tissue cells. |
|
what areas contain higher densities of capillaries? |
Areas with a great deal of metabolic activity (leg muscles, for example) have higher densities of capillaries |
|
Fenestrated capillaries (structure) |
-are similar to continuous capillaries except that the endothelial cells in fenetrated capillaries are riddled with oval pores or fenestrations -a delicate membrane, or diaphragm (basal lamina) usually covers the fenestrations |
|
what advantage have fenestrated capillaries compared to continuous capillaries? |
-fenestrated capillaries are much more permeable to fluids and small solutes than continuous capillaries are |
|
where fenestrated capillaries are located? (3) |
-they are found wherever active capillary absorption or filtrate formation occurs -ex: small intestine, endocrine organs, and kidneys |
|
sinusoid capillaries (other name, what are them, where found (4), describe structure) |
-sinusoids -are highly modified, leaky capillaries found only in the liver, bone marrow, spleen, and adrenal medulla -they have large irregular shaped lumens and are usually fenestrated (with oval pores) -Their endothelial lining has fewer thigh junctions and larger intracellular clefts than ordinary capillaries |
|
what is the function of the structural adaptations of sinusoid capillaries? |
-allow large molecules and even blood cells to pass between the blood and surrounding tissues |
|
In the liver, the endothelium of sinusoid capillaries is_and its lining includes large_(cell), which _(what do) |
-discontinuous -stellate macrophages -remove and destroy any bacteria |
|
how and why blood moves through the sinusoid capillaries? |
-blood flows sluggishly through the tortuous sinusoid channels, allowing time for it to be modified in various ways |
|
state the name of the capillary type: |
a. fenestrated capillaries b. continuous capillaries c. fenestrated capillaries d. sinusoid capillary |
|
capillary beds |
-capillaries do not function independently. They form interweaving networks called capillary beds |
|
microciculation |
the flow of blood from an arteriole to a venule (that is through a capillary bed) |
|
what are the two types of vessels of capillaries? |
-vascular shunt -true capillaries |
|
vascular shunt |
-a short vessel that directly connects the the artiole and venule at opposite ends of the bed |
|
true capillaries |
-the actual exchange vessels |
|
follow the sequence of blood through a capillary |
-terminal arteriole feeding into the bed leads into a meteriole (a vessel structurally intermediate between an arteriole and a capillary), which is continuous with the thoroughfare channel (intermediate between a capillary and a venule). Together they form the vascular shunt. The thoroughfare channel, in turn, joins the postcapillary venule that drains the bed |
|
how the true capillary is found in the capillary bed? |
-they usually branch off the metarteriole (proximal end of the shunt) and return to the throughough channel (distal end), but occasionally they spring from the terminal arteriole and empty directly into the venule |
|
precapillary sphincter (made out of what, where found and what do) |
-smooth muscle fibers -surround the roots of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary |
|
explain how precapillary sphincter works |
-blood flowing through a terminal arteriole may go either through the true capillaries or through the shunt -When the precapillary sphincters are relaxed (open), blood flows through the true capillaries and takes part in exchanges with tissue cells -When the sphincters are contracted (closed) blood flow through the shunts and bypasses the tissue cells |
|
what regulates the amount of blood flowing through the capillary bed? (2) |
-chemical conditions -arteriolar vasomotor nerve fibers |
|
list the blood vessels part of the venous system (3) |
-venules -veins -venous sinuses |
|
how venules change as they turn into larger veins? (2) |
-the diameter of successive venous vessels increases -their wall gradually thicken as they progress from venules to larger veins |
|
veins (how they are formed, how many tunics, kind of vessels, percentage of blood supply, pressure, lumen diameter, special structure within them that is not found in arteries) |
-Convergence of venules -Three tunics -Capacitance vessels (65% of blood supply) -Lower blood pressure -Large-diameter lumens -Valves |
|
venous sinuses is called_ |
coronary sinus |
|
capillaries unite to form_ (it is not capillary bed) |
venules |
|
what is the structure of postcapillary venules? |
-they are made of endothelium and around them there are pericytes |
|
how permeable are postcapillary venules? what passes through them? |
-they are extremelly porous -fluid and white blood cells move easily from bloodstream through their walls |
|
the veins thickness and diameter is_compared to arteries |
-veins have thinner walls and their lumen is larger |
|
which layers of the veins walls are thick vs thin? |
-tunica media is thin -tunica externa is the heaviest wall layer |
|
what is the consequence of having large lumens and thin walls for veins? what is the name given to them for this? (2) |
-they can accommodate large blood volume -capacitance vessels and blood reservoirs |
|
why the walls of veins can be much thinner than the wals of arteries? |
-blood pressure in veins is low |
|
because of its lower pressure, list the adaptations that veins have to ensure that veins return blood to the heart at the same rate it was pumped into the circulation (2) |
-their large diameter lumens=offer relatively little resistance to blood flow -venous valves |
|
venous valves (where found, what are them, what do, structure, similar to what) |
-found inside the veins -adaptation to prevent blood from flowing backward -formed of folds of the tunica intima, resemble semilunar valves in both structure and function |
|
where venous valves are most abundant? where they are absent? |
-in the veins of the limbs -they are absent in veins of the thoracic and abdominal body cavities |
|
venous sinuses (what are them, and made of what) |
highly specialized, flattened veins with extremely thin walls composed only of endothelium |
|
Blood entering capillaries contains high concentrations of ____________ and ____________ that diffuse out of the capillary wall and into the ________________. what remains in the blood? |
-oxygen and nutrients -tissues -plasma proteins |
|
________________pressure drives the passage of fluids and very small molecules out of the capillary at this point. |
hydrostatic |
|
At the venule end, ___________________, due to the proteins in the blood, causes much of the tissue fluid to return to the bloodstream. |
-osmosis |
|
____________________vessels collect excess tissue fluid and return it to circulation. |
lymphatic vessels |
|
Small vessels called ___________________ lead from capillaries and merge to form larger _____________ that return blood to the heart. |
-venules -veins |
|
Veins have the same three layers as arteries have and have a flap-like ___________ inside to prevent backflow of blood. |
-venous valves |
|
How do veins differ from arteries? (6) |
-low pressure blood -veins have flap-like venous valves to prevent backflow of blood -veins are thinner and less muscular than arteries -function as blood reservoir -large lumen -thicker tunica externa than tunica media (thin) |
|
Name the type of artery that matches the description: major role in dampering the pulsatile pressure of the heart contractions |
elastic arteries |
|
Name the type of artery that matches the description: vasodilation or constriction determines blood flow to individual capillary beds |
vasodilation or constriction of "arterioles" determines blood flow to individual capillary beds |
|
Name the type of artery that matches the description: have the thickest tunica media relative to their lumen size |
muscular artery |
|
what is the function of venous valves? what forms valves? |
-valves prevent blood from flowing backwards in veins -they are formed by the folds of tunica intima |
|
In the systemic circuit, which contains more blood-arteries or veins-or is the same? |
in the systemic circuit, the veins carry more blood than arteries |
|
blood flow is directly proportional to_ (2) |
Blood flow (F) is directly proportional to the difference in blood pressure (∆P) between two points in the circulation |
|
how blood flow is determined by the values of ∆P? (increase vs decrease) |
If ∆P increases, blood flow speeds up; if ∆P decreases, blood flow declines |
|
blood flow is inversely proportional to _. explain how |
-Blood flow is inversely proportional to resistance (R) -If R increases, blood flow decreases |
|
what is more important in determining local pressure: resistance vs blood pressure |
R is more important than ∆P in influencing local blood pressure |
|
what formula related flow with pressure and resistance? |
F=P/R |
|
the arteries are _ (name given to them) |
pressure reservoirs and conduits |
|
arterioles are_ |
resistance vessels that control distribution |
|
capillaries are _ |
exchange sites |
|
veins are_ |
conduits and blood reservoirs |
|
blood flow |
volume of blood flowing through a vessel, an organ, an entire circulation in a given period (ml/min) |
|
At vascular system level, blood flow is the same as_ |
cardiac output |
|
blood pressure |
-the force per unit area exerted on a vessel wall by a contained blood |
|
term blood pressure means _blood pressure (what part blood pressure) |
systemic arterial blood pressure, in the largest arteries near the heart |
|
the_in blood pressure within the vascular system provides the driving force that keeps blood moving, always from an area of _pressure to an area of _pressure, throughout the body |
-pressure gradient (differences in blood pressure within the vascular system) -high pressure to low pressure |
|
resistance |
opposition of flow and is a measure of the amount of friction blood encounters as it passes through the vessels |
|
where in body most friction is encountered? what term is given to resistance? |
-peripheral (systemic) circulation, well away from the heart, we generally use the term peripheral resistance |
|
list the 3 important sources of resistance |
-blood viscosity -vessel length -vessel diameter |
|
Resistance factors that remain relatively constant are: |
-blood viscosity and blood vessel length |
|
Resistance factor that changes frequently is: |
Changes in vessel diameter are frequent |
|
blood viscosity |
thickness or "stickiness" of the blood |
|
blood vessel length |
the longer the vessel, the greater the resistance encountered |
|
which source of resistance would change if you are dehydrated? |
-blood vessel diameter |
|
how resistance varies in relation to vessel radius? give example in which we double the radius of the vessel |
-Resistance varies inversely with the fourth power of vessel radius (one-half the diameter) -Small little change in diameter, to the 4th power more resistance. If dilated, resistance to the 4th power less. -For example, if the radius is doubled, the resistance is 1/16 as much |
|
resistance due to blood vessel diameter resistance is_(important one) |
This come into effect with small arterials that feed capillaries |
|
how small arteries vs large arteries control the flow of blood? |
-Arteries control flow of blood by resistance -Larger arteries control by pressure |
|
how sympathetic division affects arteries? |
it constricts them to have greater pressure and flow |
|
if we have a small diameter, we have_flow due to what? |
less flow due to resistance |
|
_(blood vessel) are the major determinants of peripheral resistance |
Small-diameter arterioles |
|
what forms in artherosclerosis? what are the 2 ways in which results in an increase of resistance? |
-Fatty plaques from atherosclerosis: -Cause turbulent blood flow -Dramatically increase resistance due to turbulence |
|
why small-diameter arterioles are the major determinants of peripheral resistance is important? |
because we want to major flow of blood into the tissues |
|
In artherosclerosis, the way to counterattack increase in resistance is by_ |
increasing pressure |
|
the greater viscosity, how affects resistance? |
-the greater viscosity, the less easily the molecules slide past one another and the more difficult it is to get and keep the fluid moving |
|
why blood is more viscous than water? |
-because it contains formed elements and plasma proteins, it flows more slowly under the same conditions |
|
blood vessel diameter affects_ |
peripheral resistance |
|
where within cross-section of a blood vessel blood flows faster vs slow? |
-fluid close to the wall is slowed by friction as it passes along the wall, whereas fluid in the center of the tube flows more freely and faster |
|
why small the diameter increase resistance? |
-the smaller the tube, the greater friction because relatively more of the fluid contacts the tube wall, where its movement is impeded |
|
what would be the resistance value if we double the radius of the vessel? |
-the resistance drops to 1/16 of its original value (r⁴=2⁴=16) |
|
List three factors that determine resistance in a vessel. Which of these factors is physiologically most important? |
3 factors that determine resistance are blood viscosity, vessel length, and diameter of vessel. Vessel diameter is physiologically most important |
|
Suppose vasoconstriction decreases the diameter of a vessel to one-third its size. what happens to the rate of flow through the vessel? calculate the expected size of change |
the rate of flow will decrease 81 fold from its original flow (3^4=81) |
|
the nearer the fluid is to the heart pump, the _pressure exerted on the fluid |
the greater the pressure exerted on the fluid |
|
blood as gets out of the heart and goes back, moves in what kind of pressure? |
-blood flows through the blood vessels along a pressure gradient, always moving from higher to lower pressure areas |
|
the pumping action of the heart generates blood flow, how does pressure arise? |
-pressure results when flow is opposed by resistance |
|
where systemic pressure is highest? |
-in the aorta |
|
where in the systemic pathway does blood pressure drops the steepest? |
-in the arterioles because they offer the greatest resistance to blood flow |
|
list from greatest pressure to lesser pressure found in the blood vessels |
1. aorta 2. arteries 3. arterioles 4. capillaries 5. venules 6. veins 7. venae cavae |
|
what happens if you have high pressure in the blood veins of the brain? |
can have edema, because you have too much pressure, and too much fluid than more needed, can get strokes in brain |
|
what two characteristics of veins help keep pressure so blood continues to move? |
-large lumen (less resistance) -valves that prevent backflow |
|
what two factors arterial blood pressure reflects? |
1. how much the elastic arteries close to the heart can stretch (compliance or distensibility) 2. the volume of blood forced into them at any time |
|
blood pressure is_(term used to describe how varies) |
-pulsatile= it rises and falls in regular fashion |
|
what are the 4 kinds of pressures within arterial pressure? |
-systolic pressure -diastolic pressure -pulse pressure -mean arterial pressure |
|
systolic pressure |
pressure exerted on arterial walls during ventricular contraction |
|
diastolic pressure (what it is and what happens in blood vessels to cause it) |
-lowest level of arterial pressure during a ventricular cycle -results when aortic valve closes and the walls of the aorta recoil to maintain sufficient pressure to keep the blood flowing forward into smaller vessels |
|
pulse pressure |
the difference between systolic and diastolic pressure |
|
Mean arterial pressure (MAP) |
Mean arterial pressure (MAP) – pressure that propels the blood to the tissues |
|
how can you calculate mean arterial pressure? |
MAP = diastolic pressure + 1/3 pulse pressure |
|
what artheroscleorsis does to pulse pressure? |
-it increases the pulse pressure because the elastic arteries become less stretchy |
|
How MAP and pulse pressure change with increasing distance from the heart? |
-Both decline |
|
what are the consequences of having a low vs high MAP? |
-If MAP is high: too much blood into tissues -If MAP is low: not enough blood to get nutrient and oxygen |
|
why you want low pressure at capillaries? (2) |
1. capillaries are fragile and high pressures would rupture them 2. most capillaries are extremely permeable and thus even the low capillary pressure can force solute-containing fluids (filtrate) out of the bloodstream into the intersitial space |
|
how arterial pressure compares with venous pressure? |
-unlike arterial pressure, which pulsates with each contraction of the left ventricle, venous blood pressure is steady and changes very little during cardiac cycle |
|
the low venous pressure reflects what about the veins? |
reflects the cumulative effects of the peripheral resistance |
|
Venous BP alone is too low to promote adequate blood return and is aided by the: (2) In addition, what other factor helps venous return? |
-Respiratory "pump" -Muscular "pump" -Valves prevent backflow during venous return |
|
muscular pump |
-factor that aids venous return -consists of skeletal muscle activity -As the skeletal muscles surrounding the deep veins contract and relax, they "milk" blood toward the heart, and once blood passes each successive valve, it cannot flow back |
|
respiratory pump |
-factor that aids venous return -also known as thoracic pump -it moves blood up toward the heart as pressure changes in the ventral body cavity during breathing. As we inhale, abdominal pressure increases, squeezing local veins and forcing blood toward the heart. At the same time pressure in chest decreases, allowing thoracic veins to expand and speeding blood entry into the right atrium |
|
at muscular pump, when contracting _press against a vein, they force open the _proximal to area of contraction and blood is propelled toward_. _(activity of blood) closes the _(structure opened) distal to the area of contraction |
-skeletal muscles -valves -heart -valve -backflowing of blood -valves |
|
sympathetic venoconstriction |
-reduces volume of blood in the veins (capacitance vessels) -as the layers of smooth muscle around the veins constrict under sympathetic control, venous volume is reduced and blood is pushed toward the heart |
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all the 3 functional adaptations that increase venous return will _stroke volume |
increase |
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explain why is common to have edema in people in hospitals? |
-movement is important because of muscular pump to keep venous pressure -people in hospitals is common to have edema because they cannot move and they will have fluid accumulation in parts of body |
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Blood pressure |
Blood pressure is the force of blood against the inner walls of blood vessels anywhere in the cardiovascular system, although the term "blood pressure" usually refers to arterial pressure. |
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During ventricular contraction, arterial pressure is at its _______________ (______________ pressure). |
-highest -systolic pressure |
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When ventricles are relaxing, arterial pressure is at its ______________ (______________ pressure). |
-lowest -diastolic pressure |
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The surge of blood that occurs with ventricular contraction can be felt at certain points in the body as a ___________________. |
pulse |
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How heart action affects blood pressure? |
Heart action is dependent upon stroke volume and heart rate (together called cardiac output); if cardiac output increases, so does blood pressure. |
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how blood volume affects blood pressure? include how varies (3) |
-Blood pressure is normally directly proportional to the volume of blood within the cardiovascular system. -Blood volume varies with age, body size, and gender. |
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what is peripheral resistance? how affects blood pressure? |
-Friction between blood and the walls of blood vessels is a force called peripheral resistance. -As peripheral resistance increases, such as during sympathetic constriction of blood vessels, blood pressure increases. |
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how blood viscosity affects blood pressure? |
The greater the viscosity of blood, the greater its resistance to flowing, and the greater the blood pressure. |
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Control of blood pressure: |
-cardiac output -peripheral resistance |
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maintaining blood pressure requires (2) (who involved) |
-Cooperation of the heart, blood vessels, and kidneys -Supervision of the brain |
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3 ways to increase blood pressure? |
-increase vasoconstriction (reduce diameter) -increase volume of blood -make heart to contract more |
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3 main factors that influence blood pressure |
-cardiac output -peripheral resistance -blood volume |
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formula to calculate blood pressure |
∆P= CO X R |
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cardiac output formula is |
CO= stroke volume X heart rate |
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main factors determining cardiac output are_ |
-venous return -neural and hormonal controls |
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If perform excercise, will increase or decrease the followin: |
a. increase b. increase c. increase -increase venous return that increases EDV (end diasolitc volume), which increases stroke volume -increase in stroke volume will increase cardiac output |
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Blood pressure drops, this is detected by_(part of brain), which will activate either what two systems? |
-cardiac centers of the brain in the medulla -parasympatetic and sympathetic |
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when sympatetic kicks in, what effect, how affect stroke volume? how affect heart rate? what effects ultimately? |
-increase stroke volume: affects it by increasing contractility of cardiac muscle by releasing epinephrine in blood or nervous control, which decreases end systolic volume (ESV) -increase heart rate=by increasing epinephrine in blood or nervous control -ultimately increase cardiac output |
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why contractility decreases end systolic volume? |
Contractibility decrease end systolic volume (less blood at the end of contraction) |
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what part of medulla is in charge of he heart rate most of the time? via through what nerve? what does to heart rate? |
-cardioinhibitory center -parasympathetic nerves -maintain resting heart rate |
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what cardiac center starts during stress cases? explain how and what affects? (2, what ultimately enhances) |
-during stress, the caridioacceleratory center takes over, activating the sympathetic nervous system and increasing both heart rate (by acting on SA node) and stroke volume (by enhancing cardiac muscle contractility, which decreases end systolic volume) -enhancing cardiac output |
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what are the two short term regulation of blood pressure? |
nervous system and bloodborne hormones |
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short-term regulation by the nervous system and bloodborne hormones alter the blood pressure by changing: _(2) |
-peripheral resistance -cardiac output |
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what are the long term regulation of blood pressure? (include organ involved) |
alters blood via kidneys |
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short term neural controls of peripheral resistance: (2 goals) |
-Alter blood distribution to respond to specific demands (ex: during excercise blood goes to muscles instead of digestive tract) -Maintain MAP by altering blood vessel diameter |
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neural controls operate via _(pathway) |
reflex arcs |
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what is involved in the reflex arcs of neural controls? (4) |
Baroreceptors-measure pressure Vasomotor centers of the medulla and vasomotor fibers Vascular smooth muscle |
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where are baroreceptors found? (2) |
found in arch of aorta, carotid sinuses in carotid artery |
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vasomotor center (type of mechanism, what it is) |
-neural short term mechanism -sympathetic neurons in medulla oversees changes in blood vessel diameter (especially arterioles) |
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cardiovascular center (part of what, what forms it (2), what do, alter what (2)) |
-part of neutral short term mechanism -vasomotor center plus the cardiac centers, integrate blood pressure control by altering cardiac output and blood vessel diameter |
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where is vasomotor and cardiovascular centers located? |
Found in medulla and pons sending messages to control blood vessels |
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what system helps arteries to have basal tone? |
-sympathetic nervous system |
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in the short mechanism in neural, vasomotor activity related to sympathetic activity causes: (used vs decreased) |
-Sympathetic activity causes: 1. Vasoconstriction, increased blood pressure 2. Blood pressure to decline to basal levels if decreased |
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vasomotor activity is modified by: (5) |
Baroreceptors, chemoreceptors (O2, CO2, and H+ sensitive), higher brain centers, bloodborne chemicals, and hormones |
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what chemoreceptors do? why? where found? |
-monitor O2, CO2, and H+ (pH) -need have these chemicals within ranges to have cells working properly -they are found in aortic arch, carotid sinuses |
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what is the name of the centers that are involved in regulation of blood found in the medulla oblongata? |
-cardiovascular center -vasomotor center |
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the cardiovascular center controls blood pressure by altering _(2) |
-cardiac output -blood vessel diameter |
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the cardiovascular center is formed by two groups_ |
-cardioacceleratory center -cardioinhibitory center |
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what the vasomotor center controls? |
-controls the diameter of blood vessels |
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vasomotor center transmits impulses at a fairly steady rate along _(ANS system) efferents called _fibers. These fibers innervate _. As a result. _(name of blood vessel) are almost always in _(state) |
-sympathetic -vasomotor fibers -smooth muscle of blood vessels, mainly arterioles -arterioles -vasomotor tone |
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vasomotor tone (what center, innervates what, what kind of blood vessel, what division of ANS involved, and what it is) |
-vasomotor center innervates smooth muscle of blood vessels (symphatetic division involved) of arterioles and have them in a state of moderation constriction |
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any increase in sympathetic activity, how affect diameter of blood vessels? how affect blood pressure? how this affected by decreasing sympathetic activity and how affect pressure? |
-produces generalized vasoconstrictions and raises blood pressure -decreased sympathetic activity allows the vascular muscle to relax somewhat and lowers blood pressure to basal levels |
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cardiovascular center activity is modified by inputs from (3) |
1. baroreceptors 2. chemoreceptors 3. higher brain centers |
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baroreceptors |
-pressure-sensitive mecahnoreceptors that respond to changes in arterial pressure and stretch |
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chemoreceptors |
-receptors that respond to changes in blood levels of carbon dioxide, H+, and oxygen |
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In baroreceptor reflex, Increased blood pressure stimulates the cardioinhibitory center to: (5) This results in_ |
-Increase vessel diameter -Decrease heart rate, cardiac output, peripheral resistance, and blood pressure -decrease of blood pressure |
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in baroreceptor reflex, Declining blood pressure stimulates the cardioacceleratory center to: (2) |
Increase cardiac output and peripheral resistance |
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Low blood pressure also stimulates the _(besides baroreceptor) center to _(do what?) |
-vasomotor -constrict blood vessels |
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what parts of the brain contain the cardioacceleratory and cardioinhibitory centers? (2) |
-medulla oblongata -pons |
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what is the goal of baroreceptor reflex? |
-maintain normal blood pressure range |
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The baroreceptor reflex is what length mechanism? |
short term mechanism |
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hormones can help to regulate blood pressure, both in short term via_and in the long term via_ |
-changes in peripheral resistance -increasing blood volume |
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list the hormones that have effects on blood pressure (increase blood pressure) (4) |
-adrenal medulla hormones -antidiuretic hormone (ADH) -Angiotensin II -endothelium derivatives |
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list the hormones that have effects on blood pressure (decrease blood pressure) (4) |
-atrial natriuretic peptide (ANP) -nitric oxide (NO) -inflammatory chemicals -alcohol |
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Adrenal medulla hormones (name of hormones and what do) |
norepinephrine and epinephrine increase blood pressure |
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what autonomic nervous system affect the adrenal medulla to produce its hormones? |
sympathetic nervous system |
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Antidiuretic hormone (ADH) (who produces it, what does and what fixes) (short term) |
-produced by hypothalamus -causes intense vasoconstriction in cases of extremely low BP |
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what are the long term antidiuretic homrone ADH effects on blood pressure? (2) |
-by retaining more water in body, increase blood volume and thus blood pressure -stimulates kidneys to conserve water |
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Angiotensin II (what causes its production, what it does, what fixes) |
-kidney release of renin generates angiotensin II, which causes intense vasoconstriction -fix low blood pressure by increasing it |
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what is the long term of angiostein II on blood pressure? |
-increase blood pressure -causes aldosterone and ADH to retain sodium ions (wherever goes sodium water follows), which will play as long term regulation of blood pressure by enhancing blood volume |
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Endothelium-derived factors (2) (where secreted, derived from what, what do) |
-secreted in the endothelium of blood vessles -endothelin and prostaglandin-derived growth factor (PDGF) are both vasoconstrictors (act locally) |
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atrial natriuretic peptide (ANP) (what causes (2) and how) |
-causes blood volume and pressure to decline -inhibits aldosterone, do not retain sodium (excrete it), do not retain water, decrease blood volume |
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nitric oxide (NO) (what do) |
has brief but potent vasodilator effects |
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Inflammatory chemicals (list the 3 and what do) |
histamine, prostacyclin, and kinins are potent vasodilators |
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alcohol (what do) |
causes BP to drop by inhibiting ADH |
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where does atrial natriuretic peptide produced? |
in atrium |
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the renal mechanism is what length mechanism to regulate blood pressure? |
-long term |
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the renal system organ is_ |
kideny |
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Kidneys act directly and indirectly to maintain long-term blood pressure: |
-Direct renal mechanism alters blood volume (filtering and urine) -Indirect renal mechanism involves the renin-angiotensin mechanism (produce aldosterone, retain sodium, retain water; release of ADH, water absorption; sensation of thirst activated, encouraging water intake; potent vasoconstrictor) |
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what are important roles for kidney? (2) |
Important role in wastes and controlling blood pressure |
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long term mechanism alter_ |
blood volume |
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how increase blood volume results in increase in blood pressure? |
-blood volume is a major determinant of cardiac output, via its influence on venous return, EDV, and stroke volume. -an increase in blood volume is followed by a rise in blood pressure. Decrease in blood volume results in decrease in blood pressure |
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how blood pressure varies? |
-Blood pressure cycles over a 24-hour period -BP peaks in the morning due to waxing and waning levels of retinoic acid |
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Extrinsic factors such as _(8) may also cause BP to vary |
age, sex, weight, race, mood, posture, socioeconomic status, and physical activity |
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why when you get older, your blood pressure increase? |
arteries are less flexible and pressure will increas |
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fat people have what kind of blood pressure? |
Weight=fat have higher blood pressure |
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socioeconomic status can affect your blood pressure? |
-stress for not having money, get blood pressure problems -no buy good food |
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if perform exercise, what kind of blood pressure you will have? |
low blood pressure |
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what are the 2 types of alteration of blood pressure? |
-hypertension -hypotension |
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hypotension |
low BP in which systolic pressure is below 100 mm Hg |
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hypertension |
condition of sustained elevated arterial pressure of 140/90 or higher |
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Transient elevations of tension are normal and can be caused by _(3) |
Transient elevations are normal and can be caused by fever, physical exertion, and emotional upset |
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Chronic elevation of blood pressure in hypertension is a major cause of _(4) |
Chronic elevation is a major cause of heart failure, vascular disease, renal failure, and stroke |
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what are the 3 types of hypotension? |
-Orthostatic hypotension -Chronic hypotension -Acute hypotension |
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orthostatic hypotension |
temporary low BP and dizziness when suddenly rising from a sitting or reclining position |
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chronic hypotension (hint of_and sign for_disease) |
hint of poor nutrition and warning sign for Addison’s disease |
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acute hypotension (important sign of_) |
-important sign of circulatory shock |
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acute hypotension is a threat to who especially? |
Threat to patients undergoing surgery and those in intensive care units |
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hypertension may be _(2) |
-transient -persistant |
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what are the two types of hypertension? |
-primary or essential hypertension -secondary hypertension |
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what are the risk factors in primary hypertension? (7) |
– risk factors in primary hypertension include diet, obesity, age, race, heredity, stress, and smoking |
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what are the causes of secondary hyptension? (3) |
due to identifiable disorders, including excessive renin secretion, arteriosclerosis, and endocrine disorders |
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what is the normal systolic and diastolic pressure? |
systolic: 120 Hg mm diastolic: 80 Hg mm |
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hypertension |
chronically elevated blood pressure |
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when hypotension starts to be a problem? |
-when it leads ot inadequate blood flow to tissues |
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the kidneys play an important role in maintaining MAP by influencing which variable? |
-blood volume |
|
tissue perfusion |
blood flow |
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Blood flow, or tissue perfusion, is involved in: (4) |
-Delivery of oxygen and nutrients to, and removal of wastes from, tissue cells -Gas exchange in the lungs -Absorption of nutrients from the digestive tract -Urine formation by the kidneys |
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what would be defined to be a good blood flow? |
Blood flow is precisely the right amount to provide proper tissue function |
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blood flow depends on_ |
the needs of the tissue |
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when you eat something, what would be the blood requirement by the digestive tract? how this applies when you do exercise? |
-the digestive tract will want more blood -when you are doing excercise most of the blood will go to muscles |
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blood velocity (how changes and relation to other variable) |
-Changes as it travels through the systemic circulation -Is inversely proportional to the cross-sectional area |
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why we want a slow blood velocity at the capillaries? |
Slow capillary flow allows adequate time for exchange between blood and tissues |
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what cross sectional area is found within capillaries? why? |
-Because we add all cross section of each capillary, get large cross section -even though the individual branches have smaller lumens, their combined cross-sectional areas and thus the volume of blood they can hold is much greater |
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with less cross sectional area, what velocity we get? how this applies to greater cross-sectional area? give example |
Less cross sectional area=greater velocity ex: aorta Greater cross sectional area=slow down velocity ex: capillaries |
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where does blood flow is the slowest? |
at capillaries |
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how can we control the blood flow velocity at the capillaries? |
-by constricting (slow down) or dilating (speed up) arterioles |
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rank form faster to slower blood flow: vena cava, capillary, aorta |
aorta (artery)>vena cava (vein)>capillary |
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where is blood flow the fastest? |
-at the aorta and other large arteries |
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in which the speed of blood flow is greatest: artery vs vein? |
-blood flow is greater at artery than a vein |
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blood flows fastest when the total cross-sectional area is_ |
least -speed up will increase as you decrease in cross sectional area |
|
autorregulation (what it is and what it refers to) |
-blood flow to each tissue in proportion what it needs -refers to Local Regulation of Blood Flow |
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how autorregulation works? |
Blood flow through an individual organ by modifying the diameter of local arterioles feeding its capillaries |
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how MAP is affected by local autorregulation? |
MAP remains constant, while local demands regulate the amount of blood delivered to various areas according to need |
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how constricting arterioles vs dilating affect speed? (mainly blood volume) |
-Blood flow speed up by dilating greater quantity of blood coming in -Blood flow slow down by constricting less quantity of blood coming in |
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if increase diameter by 1, how affect blood flow? |
-decrease resistance by 4 times -increase blood flow |
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fluctiations in systemic blood pressure would cause problems for individuals were it not for_responses of_(tissue) |
-myogenic responses -vascular smooth muscle |
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in myogenic responses, Vascular muscle responds directly to: (2) |
-Respond to Increased vascular pressure with increased tone, which causes vasoconstriction (respond to stretch caused by intravascular pressure with increased tone, which resists the stretch and causes vasoconstriction) -Reduced stretch promotes vasodilation, which promotes increased blood flow to the tissue |
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long term autoregulation may evolve over_(period of time) to _(reason) , through_(process name) |
-May evolve over weeks or months to enrich local blood flow -angiogenesis |
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angiogenesis |
-formation of new blood vessels -the number of blood vessels increases in the region and existing blood vessels enlarge |
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Angiogenesis takes place: (4) |
-number of vessels to a region increases -When existing vessels enlarge -When a heart vessel becomes partly occluded -Routinely in people in high altitudes, where oxygen content of the air is low |
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when you start to work out, what happens and why? |
-autogenesis -When start to work out more regularly, your muscles need more blood, as get more fibers in your muscles, get more blood vessels |
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why have angiogenesis when get fat? |
increase more blood vessels because adipose cells need blood |
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compared with other places, blood flow to brain is_(variability) why? |
-constant -as neurons are intolerant of ischemia |
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what are the metabolic controls found in the brain? (brain extremely sensitive to what) |
brain tissue is extremely sensitive to declines in pH, and increased carbon dioxide causes marked vasodilation |
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how myogenic controls protect the brain? (increase vs decrease) |
-Myogenic controls protect the brain from damaging changes in blood pressure: -Decreases in MAP cause cerebral vessels to dilate to ensure adequate perfusion -Increases in MAP cause cerebral vessels to constrict |
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what are the three types of cardiovascular shock? (also known as circulatory shock) |
-hypovolemic shock -vascular shock -cardiogenic shock |
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hypovolemic shock |
-type of cardiovascular shock or ciculatory shock – results from large-scale blood loss |
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vascular shock |
type of cardiovascular shock or circulatory shock poor circulation resulting from extreme vasodilation |
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cardiogenic shock (what it is and normal cause) |
-type of cardiovascular shock or circulatory shock -the heart cannot sustain adequate circulation -heart is so inefficient to sustain adequate circulation -normal cause is myocardial damage |
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circulatory shock |
-is any condition in which blood vessels are inadequately filled and blood cannot circulate normally -blood flow is inadequate to meet tissue needs |
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