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Autonomic Nervous System > ANS Reflexes > Flashcards

ANS Reflexes Flashcards

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1
Q

Key points of integrations between the ANS and endocrine system

A

Renin-angiotensin-aldosterone system (RAAS)

Vasopressin

Glucocorticoids

Insulin

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2
Q

Five components of the biological feedback loop (arc)

A

Sensor
Afferent pathway
Control center
Efferent pathway
Effector organ or tissue

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3
Q

Component of the biological feedback loop that monitors the environment

A

Sensor

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4
Q

Component of the biological feedback loop that detects and change in a variable

A

Sensor

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5
Q

Component of the biological feedback loop that conducts the action potential towards the control center

A

Afferent pathway

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6
Q

Most common location of control center

A

CNS

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7
Q

Component of the biological feedback loop that links the sensor and control center

A

Afferent pathway

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8
Q

Component of the biological feedback loop that modifies output to effector

A

Control center

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9
Q

Component of the biological feedback loop that maintains a set point

A

Control center

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10
Q

Component of the biological feedback loop that links the control center to the effector organ/ tissue

A

Efferent pathway

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11
Q

Pathway that is almost alway a 2- neuron pathway (pre- and post- ganglionic)

A

Efferent pathway

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12
Q

Component of the biological feedback loop that elicits a physiologic change to restor homeostasis

A

Effector

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13
Q

Effector tissues/ organs in autonomic (visceral) reflex arcs

A

Smooth muscle
Cardiac muscle
Glands

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14
Q

Fast- acting reflex loops between the cardiovascular system and CNS

A

Cardiovascular reflexes

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15
Q

Short term BP control takes place via what mechanism?

A

Neural (ANS reflexes–> mechanoreceptors)

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16
Q

Longer term BP control takes place via what mechanism

A

Hormonal (RAAS, vasopressin, natriuretic peptides)

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17
Q

List the cardiac reflexes

A

Baroreceptor
Bainbridge
Bezold- Jarisch
Chemoreceptor
Vasovagal
Oculocardiac

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18
Q

Reflex that aims at maintaining BP around a setpoint

A

Baroreceptor reflex

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19
Q

Reflex that is responsible for maintaining BP during position changes

A

Baroreceptor reflex

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20
Q

Why do patients with chronic hypertension not tolerate hypotension well?

A

Baroreceptors have adapted to the higher BP and increased the set point for autoregulation

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21
Q

Location of high-pressure baroreceptors

A

Transverse aortic arch
Bifurcations of the carotid arteries

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22
Q

Afferent pathway of baroreceptor reflex

A

Transverse aortic arch > Vagus n (CN 10)

Carotid bifurcation > carotid sinus n (Hering’s n) > glossopharyngeal n (CN 9)

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23
Q

Where is the control center for the baroreceptor reflex?

A

Nucleus tractus solitarius (NTS) in the medulla

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24
Q

The spinal cord origin of cardioaccelerator fibers

A

T1-T4

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25
Effect on baroreceptor reflex: volatile anesthetics
Impair in a dose-dependent fashion
26
Volatile anesthetic associated with the least impairment of the baroreceptor reflex
Isoflurane (has mild B1 agonist properties)
27
Effect on baroreceptor reflex: Propofol
Usually impairs
28
Effect on baroreceptor reflex: Ketamine
Activates SNS = increased HR with minimal change in SVR
29
Effect on baroreceptor reflex: Etomidate
Usually unchanged HR with small decrease in SVR
30
Effect on baroreceptor reflex: Thiopental
Preserves reflex Decrease SVR with compensatory increase in HR
31
Effect on baroreceptor reflex: hydralazine
Preserves reflex Decrease SVR d/t vasodilation and increase HR
32
Effect on baroreceptor reflex: nitroglycerine and nitroprusside
Preserved reflex
33
Effect on baroreceptor reflex: beta blockers
Impair reflex Prevent compensatory increase in HR depending on extent of B1 blockade Labetolol also blocks alpha-1 receptor and may increase the risk of orthostatic hypotension
34
Effect on baroreceptor reflex: phenylephrine
Preserves
35
Effect on baroreceptor reflex: norepinephrine
Lower doses = B1 chronotropic effects prevail As dose increases, alpha-1 vasoconstriciton overshadows and reflex is preserved
36
Reflex that slows HR in the setting of profound hypovolemia
Bezold-Jarisch reflex
37
Bezold-Jarisch triad
Bradycardia Hypotension Coronary artery dilation
38
Reflex that prevents sludging of the blood in the veins, atria, and pulmonary circulation
Bainbridge reflex
39
Reflex that increases HR and inotropy in the setting of persistent hypoxemia
Chemoreceptor reflex
40
Bainbridge reflex: stimulus
Increased blood volume
41
Bainbridge reflex: sensor
Increased firing of low-pressure stretch receptors during atrial firing
42
Bainbridge reflex: afferent pathway
Vagus (CN 10) to the nucleus tractus solitarius
43
Location of low-pressure baroreceptors
Atria Lung vasculature
44
Bainbridge reflex: control center
Nucleus tractus soltarius and its projections to CV centers in medulla
45
Bainbridge reflex: efferent pathway
PNS and SNS pathways to SA node
46
Bainbridge reflex: effector and response
SA node > increase HR
47
Bainbridge reflex: effects on contractility and stroke volume
Insignificant
48
Counterbalances the baroreceptor reflex
Bainbridge reflex
49
Cardio-inhibitory reflex that may play a prominent role in cardioprotective reflexes in response to noxious stimuli
Bezold-Jarisch
50
Chemical triggers for the Bezold-Jarisch reflex
Veratrum alkaloids, nicotine, capsaicin, histamine, sertonin, snake/ insect venoms
51
Bezold-Jarisch reflex: stimulus
Noxious ventricular stimuli (MI, low venous return, thrombolysis)
52
Bezold-Jarisch reflex: sensor
Chemo- and mechanoreceptors in the LV wall
53
Bezold-Jarisch reflex: afferent pathway
Nonmyelinated C fibers in the vagus (CN 10) to the nucleus tractus solarius
54
Bezold-Jarisch reflex: control center
Nucleus tractus solarius and medullary cardiovascular nuclei and centers
55
Bezold-Jarisch reflex: efferent pathway
Vagus (CN 10)
56
Bezold-Jarisch reflex: effector and response
SA node > decrease HR/ AV node > decrease dromotropy
57
Strongest stimulus at peripheral chemoreceptors
Hypoxia
58
Afferent pathway of peripheral chemoreceptors
Hypoxia> afferent impulse from carotid and aortic bodies > hering n (branch of CN 9) > vagus (CN 10) > nucleus tractus soliatrius
59
Effector response to hypoxia
Increased RR Increased Vt = Increased minute ventilation
60
Acute cardiovascular response to hypoxemia
Activation of PNS > decreased HR and decreased inotropy
61
Cardiovascular response to persistent hypoxemia
SNS activation > increased HR and increased inotropy = increased cardiac output
62
What drugs blunt the chemoreceptor reflex?
Subanesthetic concentrations of most volatile anesthetics (<0.1 MAC) Opioids Nitrous oxide
63
Vasovagal reflex triggers
Psychological stress Periotoneal stretching or distension
64
When is fainting more likely to occur due to vasovagal reflex?
In a warm room After a volume loss Upon standing up
65
Afferent limb of oculocardiac reflex
Long and short ciliary nerves > ciliary ganglion > ophthalmic division (V1) of trigeminal (CN 5) > trigeminal ganglion
66
Efferent limb of oculocardiac reflex
Vagus (CN 10)
67
Oculocardiac reflex: stimulus
Traction on the extraocular muscles (especially the medial rectus) Strabismus surgery Pressure on the globe Pressure on the conjunctiva Ocular trauma Pressure on the orbital tissue following enucleation Retrobulbar block (can cause or prevent)
68
Oculocardiac reflex: Sensor
Mechanoreceptors in the ocular tissues
69
Oculocardiac reflex: Control center
Nucleus soltarius tractus and medullary cardiovascular nuclei and centers
70
Oculocardiac reflex: effector and response
Decreased activity of the SA and AV nodes
71
Oculocardiac reflex: clinical presentation
Bradycardia Hypotension Junctional rhythm AV block Asystole
72
Oculocardiac reflex: factors that worsen the severity
Hypoxemia Hypercarbia Light anesthesia
73
Oculocardiac reflex: treatment options
Remove stimulus Administer 100% O2, ensure adequate ventilation, and deepen anesthetic Administer anticholinergic (atropine, glycopyrrolate)
74
Massive SNS activation due to profound decrease in medullary vasomotor centers
CNS ischemic reflex
75
Result of CNS ischemic reflex trigger
Immense vasoconstriction Profound increase in BP, often as high as the heart can create
76
Type of CNS ischemic response that results from increased intracranial pressure
Cushing Reflex
77
Cushing's Triad
Hypertension Bradycardia Irregular respirations
78
Control center for temperature maintenance
Preoptic area of the hypothalamus

Autonomic Nervous System (13 decks)

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