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VET 408: Cardio/Respiratory > Cardiovascular Reflexes > Flashcards

Cardiovascular Reflexes Flashcards

1
Q

cardiac output equation

A

CO = HR x SV

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2
Q

MAP equations

A

MAP = CO x SVR
MAP = SBP + (2xDBP) / 3

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3
Q

what is the most important factor for proper operation of the CV system

A

systemic arterial pressure

needs to be high enough to supply blood to heart and brain, but low enough to not put too much demand on the heart

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4
Q

what are short term BP regulation pathways

A

cardiac reflexes

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5
Q

what is the general pathway for cardiac reflexes

A

detector
afferent
coordinating center
efferent
effector

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6
Q

what does the parasympathetic nervous system innervate

A

SA + AV nodes
atrial cardiomyocytes

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7
Q

PNS mediators and receptors

A

mediator: ACh
receptors: muscarinic (M2, M3)
M: vessels –> vasodilation
M2: heart –> dec. chrono/dromo/ino/lusitropy

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8
Q

what does the sympathetic nervous system innervate

A

SA + AV nodes
ventricles
adrenal glands
blood vessels

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9
Q

SNS mediators and receptors

A

mediators: NE and epi
receptors: a1, B1, B2
a1: vessels –> vasoconstriction
B1: heart –> inc. chrono/dromo/ino/lusitropy
B2: vessels –> vasodilation

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10
Q

baroreceptor reflex

A

responds to acute changes in BP to attempt to normalize BP

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11
Q

baroreceptor reflex pathway

A
  1. high MAP causes vessel walls to stretch
  2. detected by baroreceptors
  3. increase firing of BRs
  4. afferent signal sent to the CV center in the medulla
  5. increase PNS, decrease SNS efferents
  6. vasodilation + decreased HR and contractility
  7. decreased MAP
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12
Q

when no stretch is detected, are baroreceptors firing

A

yes - maintain tone even at normal BPs

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13
Q

when does maximum BR activity occur

A

within normal BP ranges

responds to acute, small changes (standing, falling, etc) to prevent a large change in systemic BP

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14
Q

how does chronic systemic hypertension affect BR reflex

A

baroreceptors will adapt –> decreased sensitivity to stretch –> firing rate returns to baseline –> set point gets “reset” to a higher BP –> MAP vs stretch curve shifts right

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15
Q

what are baroreceptors

A

mechanoreceptors (stretch detectors) located in the aortic arch and carotid sinus that detect the amount and rate of stretch

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16
Q

carotid sinus BR afferents

A

hering nerve –> CN IX (glossopharyngeal)

17
Q

aortic arch BR afferents

A

aortic nerve –> vagus nerve

18
Q

bainbridge reflex

A

responds to acute changes in blood volume to attempt to move volume forward

19
Q

bainbridge reflex pathway

A
  1. increase in atrial volume causes stretch in atrial walls
  2. detected by stretch receptors in walls
  3. increases afferent signaling to CV center
  4. increase SNS, decrease PNS efferent signals
  5. increased HR and contractility
  6. increased forward flow
20
Q

examples of when Bainbridge reflex is used

A

administration of fluid bolus
respiratory sinus arrhythmia

21
Q

respiratory sinus arrhythmia + bainbridge reflex

A

inspiration creates negative intrathoracic pressure –> increases venous return to RA –> increased atrial volume –> increase SNS, decrease PNS –> increased HR during inspiration

22
Q

when is bainbridge reflex predominant vs baroreceptor reflex

A

high/normal blood volume: bainbridge predominates

low blood volume: baroreceptor predominates to maintain perfusion pressure

23
Q

chemoreceptor reflex

A

responds to severe changes in pO2 and CO2 to control BP

24
Q

chemoreceptor reflex mechanism

A
  1. low O2 and high CO2 and acidemia sensed by chemoreceptors in carotid sinus/aortic arch
  2. increase afferent signaling to CV center
  3. increase SNS, decrease PNS
  4. increase RR and MAP
25
Q

is chemoreceptor reflex used in health

A

NO - only in BP <80 mmHg causing severely low O2/high CO2

26
Q

what signaling pathways are used by the chemoreceptor reflex

A

same as baroreceptor (hering nerve to glossopharyngeal, aortic nerve to vagus)

27
Q

cushing’s response

A

responds to increases in intracranial pressure to alter BP, HR, RR

28
Q

cushing’s response pathway

A
  1. increased intracranial pressure sensed by central chemoreceptors
  2. increases peripheral vasoconstriction (shunts blood toward brain)
  3. severe increase in MAP
  4. triggers baroreceptor reflex
  5. decreases HR
29
Q

cushing’s triad

A

high systolic BP
low HR
low RR

in response to high intracranial pressure

30
Q

dive response

A

responds to submersion in cold water to decrease respiration and HR

31
Q

dive response pathway

A
  1. submersion in cold water
  2. increase PNS, decrease SNS signaling
  3. apnea, low HR, vasoconstriction
32
Q

oculocardiac reflex

A

responds to pressure on the eyes to decrease HR

33
Q

oculocardiac reflex pathway

A
  1. pressure on eyes stimulates signaling via ophthalmic branch of CN V
  2. efferent via vagus nerve
  3. bradycardia + shock
34
Q

vagal maneuver

A

pressing on the eyes for 1 min to stimulate vagal tone and decrease HR

VET 408: Cardio/Respiratory (38 decks)

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