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Unit 4 Physiology > Autonomic Control of Blood Pressure > Flashcards

Autonomic Control of Blood Pressure Flashcards

1
Q

what is the acute regulation of arterial pressure primarily mediated by?

A

high-pressure baroreceptor reflex (arterial baroreceptors)

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2
Q

describe cardiopulmonary baroreceptors

A

they are low pressure baroreceptors or volume receptors

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3
Q

what are chemoreceptors primarily concerned with?

A

respiratory control

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4
Q

what is chronic regulation of arterial pressure linked to?

A

volume control by the kidneys

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5
Q

describe baroreceptors

A

stretch receptors strategically placed in the walls of large systemic arteries
branched terminals of nerve fibers

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6
Q

where are the two most important arterial baroreceptors?

A

in the carotid sinus and the aortic arch

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7
Q

how are the impulses transmitted from the carotid sinus?

A

hering’s nerves carry the signal to the glossopharyngeal nerve which brings it to the nucleus tractus solitarius in the medulla

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8
Q

what is the integration portion of the high pressure baroreceptor reflex?

A

the nucleus tractus solitarius

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9
Q

what are the major impacts of stretching baroreceptors systemically?

A

vasodilation and bradycardia

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10
Q

what are the two major peripheral chemoreceptors?

A

the carotid body and the aortic bodies

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11
Q

why are the chemoreceptors stimulated when the arterial pressure falls below a critical level?

A

because diminished flow causes decreased oxygen and buildup of carbon dioxide and H+

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12
Q

when is the chemoreceptor reflex a powerful arterial pressure controller? what is the purpose?

A

when the arterial pressure falls below 80 mmHg

purpose is to have more stimulation to prevent further decrease in arterial pressure

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13
Q

where are the central chemoreceptors and what do they detect?

A

in the medulla and they are sensitive to decrease in brain pH (reflecting CO2 concentration)

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14
Q

what do low pressure baroreceptors detect?

A

changes in venous pressure/ volume

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15
Q

how does an increase in blood pressure translate to stimulation of baroreceptors?

A

the vessel is enlarged, deforming the receptors and increasing in the depolarization of the receptor and therefore an increased firing rate of the receptor’s sensory nerve

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16
Q

how is the baroreceptor potential different to an action potential?

A

it is a graded response whose amplitude is proportional to the degree of stretch

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17
Q

which is the most important arterial baroreceptor and why?

A

the carotid sinus receptor because it is more sensitive around normal operating pressure range than the aortic receptor

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18
Q

what pressure do not stimulate the carotid sinus baroreceptor?

A

0-50 mmHg

19
Q

what is the difference in response of the aortic baroreceptor compared to the carotid sinus?

A

they operate at different pressures (30 mmHg higher than carotid)

20
Q

when are the carotid sinus baroreceptors most sensitive?

A

during normal operating range

21
Q

how does the carotid sinus nerve firing vary without a change in mean arterial pressure?

A

it responds to the different pressures during systole and diastole (responds more to a rapidly changing pressure than stationary pressure)

22
Q

how do baroreceptors adapt to long term changes in mean arterial pressure?

A

it sets a new standard for normal operating range and will not fire abnormally at that higher set point

23
Q

what are the nerves from the baroreceptors referred to as and why?

A

buffer nerves

because they buffer blood pressure changes due to daily activities

24
Q

what occurs when baroreceptor nerves from the carotid sinuses and the aorta are lost?

A

there is a large fluctuation of blood pressure throughout the day when it is usually stable

25
Q

what vessels does the sympathetic nerve fibers innervate?

A

all but the capillaries

26
Q

how does sympathetic innervation of small arteries and arterioles decrease rate of blood flow through tissues?

A

it increases resistance to blood flow

27
Q

what does sympathetic innervation of large veins do?

A

decreases the volume of these vessels and pushes blood to the heart

28
Q

how does sympathetic innervation impact arterial pressure continuously?

A

under normal conditions, it vasoconstricts causing a partial state of contraction

29
Q

what is vasomotor tone?

A

the partial state of contraction maintained by the sympathetic nervous system

30
Q

what happens to arterial pressure with total spinal anesthesia and why?

A

the pressure falls because it blocks all transmission of sympathetic nerve impulses and therefore vasomotor tone is lost

31
Q

what is the result of an increase in mean arterial pressure?

A

baroreceptors increase their firing
parasympathetic nerves are stimulated and sympathetic nerves are suppressed
heart rate is decreased and there is vasodilation

32
Q

what is the end result of decreased MAP in response to a transient increase in MAP called?

A

baroreceptor reflex

33
Q

what effect does lying down have on mean arterial pressure? how?

A

it increases it by increasing venous return and therefore stroke volume

34
Q

what is carotid sinus massage used for?

A

stimulates baroreceptors by increasing MAP- slows the heart in people with atrial tacychardia

35
Q

what is carotid sinus syndrome?

A

when a person has hypersensitive baroreceptors so that minor pressure (even from external sources) stimulates a strong reflex. it can stop the heart

36
Q

where does the parasympathetic nervous system innervate in the circulatory system?

A

SA and AV nodes, and vessels in the genitals and lower GI tract

37
Q

where does the sympathetic nervous system innervate in the circulatory system?

A

SA and AV nodes, artreial and venous vessels and the myocardium

38
Q

what effects does the baroreceptor reflex have with high MAP and what innervation causes them?

A

lowering heart rate (PNS)

decreased peripheral resistance, decreased venous tone and decreased contractility (SNS)

39
Q

what does falling pressure in baroreceptors elicit?

A

an immediate, strong sympathetic reflex that minimizes the decrease in pressure

40
Q

what does the valsalva maneuver test?

A

the integrity of the baroreceptor reflex

41
Q

describe the valsalva maneuver

A

patient expires against a closed glottis which increases intrathorasic pressure and decreases mean arterial pressure (decreases venous return)

42
Q

what is experienced after release from the valsalva maneuver?

A

a rebound decrease in heart rate

43
Q

where do inhibitory interneurons project from and to?

A

from the neucleus tractus solitarii to the vasomotor area

Unit 4 Physiology (31 decks)

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