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Physiology > Week 8: Reflex control of circulation > Flashcards

Week 8: Reflex control of circulation Flashcards

1
Q

What results in the elimination of the sympathetic nerve activity?

A

drop in the mean aterial pressure

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2
Q

Sympathetic nerves innervate what elements of the cardiovascular system?

A
  • blood vessels
  • heart
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3
Q

Sympathetic nerves innervate which type of vessels?

A
  • resistance vessels (arteries)
  • capacitanec vessels (veins)
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4
Q

What innervation does the heart recieve?

A
  • sympathetic (SA, AV node + cardiac muscle)
  • parasympathetic ( only SA and AV nodes)
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5
Q

What is the pathway of the negative feedback regulation?

A

Setpoint → discriminator → forward signal → effector/s → regulated paramter → feedback signal

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6
Q

What are the three different types of receptors?

A
  1. high pressure receptors
  2. low pressure receptors
  3. chemoreceptors
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7
Q

What are the high pressure receptors and where are they located?

A

baroreceptors

located in the carotid sinus and in the aorta

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8
Q

Describe the baroreceptors in the carotid sinus

A
  • predominantly elastic fibers (no collagen, no smooth muscle)
  • sensitive to ↑ transmural pressure
  • distention → stretch receptors
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9
Q

What is the graph displaying the relationship between arterial pressure and sinus nerve activity? What is significant?

A

The slope is largest at normal physiological range therefore the firing rate is very susceptible to change.

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10
Q

What is the major difference between the carotid baroreceptors and the aortic baroreceptors?

A

The dynamic range of the carotid baroreceptors is higher than the aoritc baroreceptors

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11
Q

Explain the graph displaying that the receptor potential ch changes in response to the elevation of arterial blood pressure

A
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12
Q

What are the receptor potential changes converted to?

A

action potential frequencies

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13
Q

Explain the graph

A

if the carotid is clamped the pressure in the carotid sinus is reduced due to the lack of blood flow

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14
Q

What is the graph representing the relationship between the isolated carotid sinus and systemic pressure?

A
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15
Q

Schematic scheme of the feed back regulation in response to ↑ mean arterial pressure

A
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16
Q

What is the response to sustained hyper tension in regards to the firing of the baroreceptors?

A
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17
Q

Where are the signals “passed to” when the receptors receive a high pressure signal?

A

aortic baroreceptors → vagus nerve

carotid sinus baroreceptors → herings nerve → glossopharingeal nerve

18
Q

What makes up the cardioinhibitory area?

A
  • dorsal motor nucleus of vagus (CN X)
  • nucleus ambiguss (CN X and part of CN IX)
19
Q

What is the pressure response in upright position?

A

correcting reflex activated within seconds

  • venomotor activity (heterometric heart regulation)
  • increased heart rate
  • vasoconstriction
20
Q

What is the pressure response when there is severe heamorhage?

A
  • vasoconstriction
    • splanchnic area
    • kidney
21
Q

What is the pressure response when there is heart stress?

A

skin vasodilation

22
Q

What is the pressor response ?

A

the reduction of blood pressure in the high pressure system

23
Q

Arterial blood pressure is normally kept in a relatively narrow range, what happens in the absence of high pressure baroreceptors?

A

large fluctuations

24
Q

Where are baroreceptors in the low pressure system located? what do they do?

A

in the right atrium

sense primarily blood volume changes

25
Q

What is the end result of intravenous infusion?

A

intravenous infusion

↓

increased right atrial pressure

↓

atrial receptors stimulated

↓

bainbrige reflex

↓

increased heart rate

End result: ↑ANP, ↓RAS

does NOT cause vasoconstriction

dilates renal arteries

prevents “stall blood” in veins

26
Q

What happens in the situation of simultaneous pressure change in the arteries ?

A

vasoconstriction

27
Q

What happens to low pressure receptors during volume depletion?

A

(fill gap with ↓ atrial receptor activity)

28
Q

What happens during inspiration?

A

​1. ↑ tension of the right atrium “bainbridge like effect”

  1. ↓ stroke volume
  2. respiratory center activity ↑

tension of lung mechanoreceptors ↑

3 composes the “crosstalk” (b/w respiratory and cardiac center)

29
Q

What happens during sinus arrythmia?

A
30
Q

What higher neural centers can modify medullary regulation?

A

motor cortex

cingulate

31
Q

What role do chemoreceptors play?

A

dedicated to the regulation of the respiration

stimulate respiratory center

↑ ventillatory drive

32
Q

Graph displaying the differencein sensitivities of chemoreceptors and baroreceptors

A

chemoreceptors operate only in times of emergency

33
Q

What are the two classifications of chemoreceptors?

A
  1. central chemoreceptors (in medulla)
  2. peripheral chemoreceptors (aortic bodies, carotid bodies)
34
Q

Draw the relation of intrinsic cardiovascular response to hypoxia, acidosis, and hypercapnia

A
35
Q

Draw the cardiovascular/ respiratory response to hypoxia, acidosis, and hypercapnia

A
36
Q

What is the cushings reflex?

A

↑ intracranial pressure

causes ischemic response of the central baroreceptor area

37
Q

What does increaed intracranial pressure cause?

A
  • strongly reduced blood flow in the medullary region
  • activation of the vasomotor mechanism and cardioinhibitory area (vagus)
  • bradycardia and very strong vasocontstriction “at any cost”
    • kidneys could even ceise urine production due to how intense the vasoconstriction is
38
Q

What happens in the Bezold-Jarish reflex?

A

the receptors in the left ventricular wall are effected (mechano and chemosensitive)

  • bradycardia and hypotension (↑ parasymp and ↓ symp vasomotor activity)
  • cardioprotective

can be activated e.g in myocardial ischemia/ infarction

39
Q

What happens in moderate pain?

A

activation of vasomotor center

↑ heart rate and ↑ blood pressure

40
Q

What happens in the occurence of strong pain and visceral pain?

A

parasympathetic activation

hypotension, bradycardia

Physiology (28 decks)

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