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Cardio > Regulation of Blood Flow > Flashcards

Regulation of Blood Flow Flashcards

1
Q

What is the equation for Ohm’s Law?

A

Q= deltaP/R

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2
Q

What is the equation for arterial pressure?

A

deltaP= CO X TPR

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3
Q

How does the body change the perfusion pressure?

A

altering the resistance (does not make sense to change the perfusion pressure)

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4
Q

What law do we use to account for turbulent flow?

A

Poiseuille’s Law

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5
Q

What is Poiseuille’s Law?

A

Q= pi(radius)^4delatP / 8 * viscosity * tube length

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6
Q

A higher Reynold’s number means what about turbulence?

A

the higher Reynold’s number, the more turbulent the flow (high resistance, reduced flow)

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7
Q

Name the 3 determinants of rapid vascular resistance regulation?

A

1) Regulation by local factors (active and reactive hyperemia)
2) Regulation by SNS
3) Regulation by humoral (circulating factors)

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8
Q

Name the 3 determinants of slow vascular resistance regulation?

A

1) Decrease in vessel lumen size (hypertrophy)

2) Change in vessel number (vascularity)

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9
Q

What is active hyperemia?

A

when blood flow goes up in organs with increased function (ex. like during exercise)

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10
Q

what causes decreased blood flow to organs that are not needed for exercise during exercise?

A

increased sympathetic activity (attempts to decrease demand on the heart)

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11
Q

What is reactive hyperemia?

A

increase in blood flow above resting level that follows reduction of blood flow to a specific tissue (blood flow is inversely related to oxygen tension)

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12
Q

The magnitude and duration of hyperemia is related to what factor?

A

the length of reduction of blood flow (ischemia)

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13
Q

What is the basic mechanism of hyperemia?

A

vasodilation in response to decrease in tissue oxygen in order to increase blood flow to oxygen starved tissues

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14
Q

How does low oxygen stimulate vasodilation?

A

1) Low oxygen decreases SM cell metabolism which will decrease SM force generation (may lead to vascular relaxation)
2) Small arteries MAY have an oxygen-sensing capacity that leads to vascular relaxation

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15
Q

What are the important vasodilator metabolites?

A

ATP, ADP, AMP, CO2, Lactic Acid, K+

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16
Q

Why do vasodilator metabolites accumulate in active hyperemia?

A

they are generated at a higher rate than can be efficiently removed

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17
Q

Why do vasodilator metabolites accumulate in reactive hyperemia?

A

the metabolites are not removed properly due to the ischemia

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18
Q

What is autoregulation?

A

the capacity of blood vessels to oppose changes in blood flow that are imposed by changed blood pressure

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19
Q

Describe metabolic control of autoregulation?

A

increased pressure leads to increased flow to tissue that flushes out metabolites and leads to high oxygen levels which stimulates vasoconstriction that decreases flow

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20
Q

Describe myogenic control of autoregulation?

A

Increased pressure leads to increased flow that stretches vessel and activates calcium stretch channels. This results in an increased forceful vasoconstriction which decreases flow.

21
Q

What blood vessels ARE NOT innervated?

A

capillaries

22
Q

What areas have dense innervation by the ANS?

A

cutaneous
renal
splanchnic
skeletal muscle

23
Q

What areas have sparse innervation by the ANS?

A

cerebral

coronary

24
Q

What does epinephrine react with at low concentrations?

A

beta receptors

25
Q

What does epinephrine react with at higher concentrations?

A

alpha receptors (especially alpha 1)

26
Q

Name the 2 circulating vasoconstrictors? How do these work?

A

angiotensin II
vasopressin
Both of these work to decrease urine output in the kidneys AND are direct vasoconstrictors

27
Q

Name the circulating vasodilators?

A

bradykinin, histamine (also increases vascular permeability), prostaglandins

28
Q

What is the role of atrial natriuretic peptide?

A

directs kidneys to increase urine output

29
Q

What is the role of nitric oxide?

A

released with increased extracellular ATP and shear stress–decrease intracellular calcium and induce vasodilation in LARGE vessels upstream of hyperemic tissues

30
Q

What is rarefaction?

A

decrease int he number of blood vessels in tissue

31
Q

What may induce antiogenesis?

A

ischemia

32
Q

What are the angiogenic factors?

A

FGF, VEGF, angiogenin

33
Q

What is hypertrophic vascular remodeling?

A

reduction in the size of the vascular lumen

34
Q

What are the most important factors regulating coronary blood flow?

A

metabolic end products

altered oxygen levels

35
Q

What chemical is thought to contribute to aroudn 25% of exercise-induced vasodilation?

A

norepinephrine

36
Q

During what part of the cardiac cycle does the left side of the heart have the lowest blood flow? Why?

A

systole

Mechanical compression of arteries during systole increases left coronary artery resistance during systole

37
Q

What allows the left side of the heart to get back blood after each ischemic episode with contraction?

A

reactive hyperemia during diastole occurs (pressure must be low during this time in order for the heart to be adequately perfused)

38
Q

What controls skeletal muscle vessels at rest?

A

SNS

39
Q

What controls skeletal muscles during exercise?

A

local control (NO, prostaglandins, potassium, etc.)

40
Q

Why does reactive hyperemia occur in skeletal muscles during exercise?

A

because each mechanical compression of arteries stops blood from flowing to the tissue (brief ischemia)

41
Q

Why does active hyperemia occur in skeletal muscles during exercise?

A

because they are increasing their function

42
Q

What is the major control of cerebral circulation?

A

local control (CO2, ADENOSINE, NO, prostaglandins)

43
Q

What type of hyperemia occurs upon neuronal stimulation?

A

active hyperemia

44
Q

What occurs in splanchnic blood vessels at the start of a meal?

A

vasoconstriction

45
Q

What occurs in splanchnic blood vessels due to the SNS as we eat?

A

active hyperemia increases vasodilation (decreases resistance)

46
Q

What controls vessels in the skin?

A

almost entirely controlled by the SNS

47
Q

The hypothalamus controls activity of what structures in the skin?

A

arteriovenous anastomoses

48
Q

What occurs when the skin is heated?

A

decreased sympathetic activity to anastomoses which leads to vasodilation and increased blood flow to skin to encourage evaporation of heat

49
Q

What happens when the skin is cooled?

A

hypothalamus senses this and causes vasoconstriction of arteriovenous anastomoses leading to decreased blood flow to skin to prevent heat loss

Cardio (24 decks)

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