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BIOL 364 > Circulation 6 > Flashcards

Circulation 6 Flashcards

1
Q

regulation of blood flow

A
  • arterioles control blood distribution
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2
Q

how do arterioles control blood distribution (2)

A
  • due to parallel arrangement, arterioles can alter blood flow to various organs
  • changes in resistance using vasoconstriction and vasodilation alter flow
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3
Q

control of vasoconstriction and vasodilation (3)

A
  • autoregulation
  • intrinsic factors
  • extrinsic factors
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4
Q

control of vasoconstriction and vasodilation: autoregulation

A
  • direct response of the arteriole smooth muscle
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5
Q

control of vasoconstriction and vasodilation: intrinsic factors

A
  • metabolic state of tissues/oxygen demand
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6
Q

control of vasoconstriction and vasodilation: extrinsic factors

A
  • nervous and endocrine system
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7
Q

under resting conditions, which organs receive larger majorities of blood flow (4)

A
  • brain
  • liver and digestive tract
  • kidneys
  • skeletal muscle
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8
Q

under resting conditions, which organs receive smaller amounts of blood flow (3)

A
  • heart
  • skin
  • bone
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9
Q

distribution of blood to tissues: increased flow

A
  • relaxation of pre-capillary sphincters allow for blood to flow to the capillary beds
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10
Q

distribution of blood to tissues: decreased flow

A
  • contraction of pre-capillary sphincters reduces blood flow to the capillary bed and blood is diverted elsewhere
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11
Q

myogenic autoregulation of flow (2)

A
  • some smooth muscle cells in arterioles are sensitive to stretch
  • smooth muscles cells ‘automatically’ contract when blood pressure increases
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12
Q

myogenic autoregulation of flow: feedback loop type

A
  • negative feedback loop
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13
Q

what is the purpose of the myogenic autoregulation of flow

A
  • to prevent excessive flow of blood into tissue
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14
Q

metabolic activity of tissues on flow (3)

A
  • smooth muscle cells in arterioles sensitive to conditions of extracellular fluid
  • levels of metabolites alter vasoconstriction/vasodilation
  • blood flow matched to metabolic requirements
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15
Q

extracellular fluid (2)

A
  • plasma of the blood
  • interstitial fluid
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16
Q

metabolic activity of tissues on flow: feedback loop type

A
  • negative feedback loop
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17
Q

increased metabolic rate in tissues: pathway step (5)

A
  1. increased tissue metabolic rate results in low O2 and high CO2 and waster
  2. arteriolar smooth muscle detect conditions and vasodilate
  3. vessel resistance is lowered, increasing blood flow
  4. O2 delivery, CO2 and waste removal increase
  5. tissue O2 increase and tissue waster and CO2 decrease, creating the negative feedback loop
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18
Q

neural and endocrine control of flow (4)

A
  • norepinephrine
  • decreased sympathetic tone
  • vasopressin (ADH)
  • angiotensin II
  • atrial natriuretic peptide (ANP)
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19
Q

neural and endocrine control of flow: norepinephrine (2)

A
  • from sympathetic neurons
  • causes vasoconstriction
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20
Q

neural and endocrine control of flow: decreased sympathetic tone

A
  • causes vasodilation
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21
Q

neural and endocrine control of flow: vasopressin (ADH) (2)

A
  • from posterior pituitary
  • causes generalized vasoconstriction
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22
Q

neural and endocrine control of flow: angiotensin II (2)

A
  • produced in response to decreased blood pressure
  • causes generalized vasoconstriction
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23
Q

neural and endocrine control of flow: atrial natriuretic peptide (ANP) (2)

A
  • produced in response to increased blood pressure
  • promotes generalized vasodilation
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24
Q

vertebrate circulatory system: blood pressure changes (3)

A
  • blood pressure in left ventricle changes dramatically with systole and diastole
  • pressure decreases as blood moves from left ventricle to arteries, arterioles, capillaries, venules, and veins
  • pressure and pulse/degree of pressure oscillation decrease in arterioles after leaving the ventricle
25
Q

why does the degree of oscillation/pulse decrease in the arterioles

A
  • higher resistance in the arterioles
26
Q

vertebrate circulatory system: average blood velocity changes (3)

A
  • highest in arteries
  • lowest in capillaries
  • intermediate in veins
27
Q

vertebrate circulatory system: total cross-sectional area (2)

A
  • lowest in the arteries and veins
  • highest in the capillaries
28
Q

why are pressure fluctuations in the arteries smaller than those in the left ventricle (3)

A
  • aorta acts as a pressure reservoir, dampening pressure fluctuations
  • due to elasticity of vessel wall
  • important for protection of downstream vessels from intense fluctuations and to even out blood flow
29
Q

how does the vessel wall act during systole and diastole (2)

A
  • expands during systole
  • elastic recoil during diastole
30
Q

vein structure (2)

A
  • thin, compliant walls
  • less constrictive due to lower muscle volume, making it more compliant to stretching
31
Q

vein functions (2)

A
  • volume reservoir
  • small increases in blood pressure lead to large changes in volume of the veins
32
Q

how much blood is held in the veins of mammals

A
  • more than 60% of the blood
33
Q

veins: control (2)

A
  • vein volume and return is controlled by sympathetic nerves
  • venomotor tone ensures pressure is sufficient to fill heart
34
Q

why can it be difficult to move blood in veins back to the heart

A
  • it is under low pressure
35
Q

how do vertebrates move blood back to the heart (2)

A
  • two pumps assist in moving blood back to heart
  • valves in veins assure unidirection flow
36
Q

moving blood back to the heart: pumps (2)

A
  • skeletal muscle
  • respiratory pumps
37
Q

moving blood back to the heart: skeletal muscle pump

A
  • contraction (shortening and thickening) of muscles squeeze the veins
38
Q

moving blood back to the heart: respiratory pumps

A
  • pressure changes in thoracic cavity during ventilation
39
Q

what is the primary driving force for blood flow through organs

A
  • blood pressure/mean arterial pressure
40
Q

mean arterial pressure

A

MAP = CO x TPR

41
Q

CO

A
  • cardiac output
42
Q

TPR

A
  • total peripheral resistance
43
Q

regulation of blood pressue

A
  • body varies cardiac output and total peripheral resistance to main near constant MAP
44
Q

how does the number of RBCs affect MAP (3)

A
  • affects blood viscosity
  • blood velocity affects TPR
  • TPR affects MAP
45
Q

how does vasopressin and angiotensin II affect MAP: non-kidneys (3)

A
  • hormones affect arteriolar tone
  • arteriolar tone affects TPR
  • TPR affects MAP
46
Q

how does vasopressin and angiotensin II affect MAP: kidneys (5)

A
  • hormones affect kidney salt + water balance
  • balance between interstitial fluid and blood is altered, changing the blood volume
  • blood volume affects venous return and EDV
  • EDV affects SV, which affects CO
  • CO affects MAP
47
Q

how does the sympathetic nervous system/epinephrine affect MAP: TPR side (3)

A
  • it affects arteriolar tone
  • tone affects TPR
  • TPR affects MAP
48
Q

how does the sympathetic nervous system/epinephrine affect MAP: CO side (3)

A
  • it increases HR and SV
  • increased HR and SV result in increased CO
  • increased CO causes increased MAP
49
Q

how do metabolites and paracrines affect MAP (3)

A
  • affect arteriolar tone
  • tone affects TPR
  • TPR affects MAP
50
Q

how does the parasympathetic nervous system affect MAP (3)

A
  • decreases HR
  • decreased HR causes decreased CO
  • decreased CO causes decreased MAP
51
Q

how does increased blood volume affect MAP (4)

A
  • increases venous return and EDV
  • increases SV
  • increases CO
  • increases MAP
52
Q

how does increased respiratory and skeletal muscle pumps affect MAP (4)

A
  • increases venous return and EDV
  • increased SV
  • increases CO
  • increases MAP
53
Q

baroreceptors (2)

A
  • stretch-sensitive mechanoreceptors in the walls of major blood vessels
  • present in carotid arteries and aorta
54
Q

baroreceptor function

A
  • send nerve signals to medulla oblongata, the cardiovascular control center
55
Q

baroreceptor reflex (2)

A
  • regulates MAP
  • negative feedback system
56
Q

baroceptor reflex: how does baroceptor firing affect norepinephrine release

A
  1. increased MAP causes in increased baroceptor firing
  2. stimulated afferent neurons and the cardiovascular control center (medulla)
  3. decreased sympathetic output results in decreased norepinephrine release
57
Q

baroreceptor reflex: how does decreased NE from baroreceptor firing affect MAP (4)

A
  • arteriolar smooth muscle undergoes vasodilation to decrease peripheral resistance -> decreased MAP
  • ventricular myocardium decreases force of contraction to decrease cardiac output -> decreased MAP
  • SA node decreases heart rate to decrease cardiac output -> decreased MAP
  • creates negative feedback loop
58
Q

how do kidneys help maintain blood volume (3)

A
  • increases in blood volume lead to increase in blood pressure
  • kidneys excrete or retain water to adjust blood volume and pressure
  • form a negative feedback loop to regulate pressure
59
Q

kidney feedback loop: steps (6)

A
  1. high arterial pressure
  2. kidneys excrete Na+ and H2O to reduce plasma volume
  3. blood volume and venous pressure decrease, decreasing EDV
  4. cardiac muscles contractility decreases (Frank-Starling effect)
  5. stroke volume decreases
  6. cardiac output decreases, decreasing arterial pressure

BIOL 364 (44 decks)

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