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PHGY-210 > Cardiovascular System - Lecture 8 > Flashcards

Cardiovascular System - Lecture 8 Flashcards

1
Q

Why are there changes in R, HR and SV?

A

to maintain flow

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2
Q

What is the idea of the Frank Starling mechanism?

A

if you stretch a muscle out, it will contract with a greater force

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3
Q

What is the normal value of EDV?

A

140 mL

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4
Q

What would happen to ventricular filling if EDV increased to 210?

A

it would increase

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5
Q

What value would SV go up to if EDV was increased to 210?

A

it would go to 110

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6
Q

What is the Frank Starling Mechanism important in?

A

exercise

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7
Q

What is preload?

A

ventricle wall stretch

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8
Q

What are the 2 indices of preload?

A

EDV and P(RA)

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9
Q

What is the end diastole volume equal to?

A

preload

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10
Q

What do some critical organs to do maintain flow?

A

autoregulation

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11
Q

What happens to coronary flow when perfusion pressure decreases?

A

it decreases

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12
Q

Why does the pressure in the coronary flow increase after 10 seconds when coronary perfusion pressure decreases?

A

because the resistance drops

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13
Q

If the pressure drops, the flow ___

A

drops

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14
Q

How does autoregulation maintain flow?

A

by dilating arterioles

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15
Q

What is the autoregulatory range?

A

a wide range of pressures (40-160 mmHg) increasing the pressure above or below 120 will result in relatively minor changes to coronary flow

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16
Q

At very low and very high pressures the effect is ___.

A

lost

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17
Q

What are the two mechanisms responsible for autoregulation?

A

myogenic mechanism and metabolic mechanism

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18
Q

What is part of the metabolic mechanism autoregulation?

A

decrease in O2, increase in metabolites

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19
Q

What is part of the myogenic mechanism autoregulation?

A

decrease in vessel-wall stretch in organ

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20
Q

What are the 5 steps in autoregulation?

A
  1. decrease in arterial pressure in organ
  2. decrease blood flow to organ
  3. metabolic or myogenic mechanisms
  4. arteriolar dilation in organ
  5. restoration of blood flow toward normal in organ
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21
Q

How do the metabolic and myogenic mechanisms operate?

A

concurrently

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22
Q

What are the 4 steps in autoregulation during exercise?

A
  1. increase in metabolic activity of organ
  2. O2 decreases, increase in metabolites in organ ISF
  3. arteriolar dilation in organ
  4. increased blood flow to organ
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23
Q

When is the metabolic mechanism triggered?

A

during increased activity (increased waste buildup)

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24
Q

What causes local metabolic control?

A

exercise

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25
Q

Why is it called ‘local’ metabolic control?

A

because it applies to a specific muscle or organ

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26
Q

What is another name for local metabolic control?

A

hyperemia

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27
Q

How can you control cardiac output?

A

by changing heart rate and stroke volume

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28
Q

How can you control mean arterial pressure?

A

by changing CO, SV and TPR

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29
Q

What does the sympathetic system modulate? (3)

A

HR, SV and TPR

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30
Q

What does the parasympathetic system modulate? (1)

A

HR

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31
Q

What happens to plasma epinephrine to increase SA node activity (HR)?

A

it increases

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32
Q

What happens to the activity of the sympathetic and parasympathetic nerves to the heart to increase SA node activity (HR)?

A

sympathetic nerves: increase
parasympathetic nerves: decrease

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33
Q

What rhythm controls HR?

A

sinus node rhythm

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34
Q

What is the sinus node rate modulated by?

A

sympathetic and parasympathetic innervation

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35
Q

What is the pathway of parasympathetic control of heart rate?

A
  • Preganglionic axon goes to a ganglion (cluster of neurons) –in the cardiac fat pads.
  • ACh causes ganglion neurons to fire after binding nicotinic receptors
  • This results in ACh release in the sinus node, which binds muscarinic receptors.
36
Q

Where re preganglionic axons found in the parasympathetic control of HR?

A

medulla

37
Q

What causes ganglion neurons to fire after binding nicotinic receptors in the parasympathetic control of heart rate?

A

acetylcholine

38
Q

What receptors does acetylcholine bind to when it is released in the sinus node (parasympathetic control of HR)?

A

muscarinic receptors

39
Q

What does the parasympathetic control of HR do to neural activity and beat rate?

A

neural activity: increase
beat rate: decrease

40
Q

What does atropine do in response to low HR?

A

binds and blocks the muscarinic receptor

41
Q

Where are preganglionic neurons found in the sympathetic control of HR?

A

spinal cord

42
Q

Where are the ganglia located in the sympathetic system compared to the parasympathetic system?

A

next to spinal cord (instead of in fat pads)

43
Q

What does the pre- and postganglionic axons release in the sympathetic control of HR?

A

preganglionic: ACh
postganglionic: norepinephrine

44
Q

What does norepinephrine on the sinus node bind to during sympathetic control of HR?

A

B-adrenergic receptor

45
Q

What does the sympathetic control of HR do to neural activity and beat rate?

A

neural activity: increase
beat rate: increase

46
Q

What is the function of B-antagonists?

A

prevents binding and lowers HR

47
Q

What is the function of B-agonists?

A

binds and increases HR

48
Q

What neurotransmitter increases stroke volume?

A

norepinephrine

49
Q

Does B-agonist increase or decrease stroke volume?

A

increase

50
Q

Does B-blocker increase or decrease stroke volume?

A

decrease

51
Q

What does B-agonist do to max force, force increase rate and duration of contraction?

A

max force: +
force increase rate: +
duration of contraction: -

52
Q

Why do we need to control vessel diameter?

A
  1. metabolic local control
  2. to change MAP
53
Q

What is the pathway of sympathetic control of vessel tone?

A

similar to pathway used for HR and SV

54
Q

What does NE bind to in the sympathetic control of vessel tone?

A

alpha-adrenergic receptor

55
Q

Are capillaries surrounded by smooth muscle?

A

no

56
Q

Are arteries, arterioles, venules and veins surrounded by smooth muscle?

A

yes

57
Q

What do alpha-agonists do to TPR and MAP?

A

TPR: increase
MAP: increase

58
Q

What do alpha-blockers do to TPR and MAP?

A

TPR: decrease
MAP: decrease

59
Q

Where does the adrenal medulla come from?

A

cells of the neural crest

60
Q

Does the adrenal medulla have an associated external ganglion?

A

no

61
Q

What parts of the adrenal medulla innervated by?

A

preganglionic axons that release ACh

62
Q

What do cells in the adrenal gland synthesize and release?

A

NE and E

63
Q

What kind of agonists are NE and E?

A

beta agonists

64
Q

What do NE and E affect? (4)

A

HR, SV, TPR, MAP

65
Q

Do baroreceptors act quickly or slowly?

A

quickly

66
Q

Does the renal system act quickly or slowly?

A

slowly

67
Q

What can baroreceptors change? (3)

A

HR, TPR, SV

68
Q

What can the renal system control?

A

total fluid volume

69
Q

Which is the strongest: baroreceptors or renal?

A

renal

70
Q

When do baroreceptors have maximal gain?

A

at healthy normal BP range (120mmHg)

71
Q

When does the CNS ischemic reflex work?

A

when Bp is dangerously low

72
Q

What is the baroreflex?

A

fast response to blood pressure changes

73
Q

Where do baroreceptors come from?

A

carotid arteries

74
Q

What do baroreceptors sense?

A

pressure

75
Q

What is the pathway of baroreceptors?

A
  1. afferent arm
  2. signal brainstem
  3. motor arm activated
76
Q

Where are the 2 locations of the baroreceptors?

A

aortic arch and carotid sinus

77
Q

What happens to the aorta and carotid sinus after each heartbeat?

A

they stretch

78
Q

What happens to BP when you stand up?

A

it drops

79
Q

What happens to sympathetic and parasympathetic tone when you stand up?

A

sympathetic: increase
parasympathetic: decrease

80
Q

What 4 things increase when baroreceptor firing decreases?

A

HR, SV, TPR, venous return

81
Q

Is an increase in HR by baroreceptors part of sympathetic or parasympathetic control?

A

both

82
Q

Is an increase in SV by baroreceptors part of sympathetic or parasympathetic control?

A

sympathetic

83
Q

Is an increase in TPR by baroreceptors part of sympathetic or parasympathetic control?

A

sympathetic

84
Q

Is an increase in venous return by baroreceptors part of sympathetic or parasympathetic control?

A

sympathetic

85
Q

What does the parasympathetic system impact?

A

HR

86
Q

What does the sympathetic system impact? (4)

A

HR
contractility
constriction of veins and arterioles
activation of adrenal glands

PHGY-210 (36 decks)

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