B7.010 Prework: Autonomic Nervous System Basics

Question 1

sympathetic nervous system

Answer 1

thoracolumbar outputs

• preganglionic fibers terminate in ganglia (paravertebral chains)
• postganglionic sympathetic fibers innervate peripheral tissues

Question 2

adrenal medulla

Answer 2

modified sympathetic ganglion

receives sympathetic preganglionic inputs and releases epi and NE into the blood

Question 3

parasympathetic nervous system

Answer 3

craniosacral outputs

• preganglionic fibers terminate in parasympathetic ganglia
• postganglionic fibers originate in ganglia and innervate organs

Question 4

enteric nervous system

Answer 4

walls of GI system
myenteric and submucous plexi
received preganglionic PNS and postganglionic SNS inputs

Question 5

general function of the ANS

Answer 5

largely autonomous
-not under conscious control
concerned primarily with visceral functions
-CO, blood flow, digestion
afferent sensory inputs drive activity (baroreceptors)
output through reflex arcs of varying size and complexity

Question 6

SNS components

Answer 6

fight or flight
thoracolumbar
intermediolateral cell column
major ganglia (cervical / mesenteric)
adrenal medulla

Question 7

PNS components

Answer 7

rest and digest
craniosacral
cranial nerves:
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X (vagus)

Question 8

ANS innervation of blood vessels

Answer 8

SNS only

Question 9

ANS innervation of most organ systems

Answer 9

mixed autonomic tone

GI and GU more PNS

Question 10

PNS nerve structure/ orientation

Answer 10

1:1 preganglionic: postganglionic nerves
more specific
long preganglionic and short postganglionic nerves
ganglia close to targets

Question 11

SNS nerve structure/ orientation

Answer 11

1:10 preganglionic: postganglionic nerves
more diffuse
short preganglionic and longer postganglionic nerves

Question 12

ANS receptor types

Answer 12

within ganglia of PNS and SNS, muscarinic receptors
postganglionic SNS mostly adrenergic, some dopamine (renal vascular) and muscarinic (sweat glands)
postganglionic PNS mostly muscarinic

Question 13

central integration of ANS

Answer 13

midbrain and medulla
integration of information from sensory inputs and higher CNS influence
output by SNS, PNS, and endocrine system are integrated

Question 14

PNS production of energy conservation

Answer 14

major underlying tone at most end organs (except vasculature)
slowing of the heart and stimulation of digestive activity

Question 15

SNS recruitment in stress

Answer 15

brief discharges with functional outcomes
cardiac stimulation
increased blood glucose
cutaneous vasoconstriction

Question 16

function of autonomic reflexes

Answer 16

control cardiovascular homeostasis
main variable is MAP
-if MAP is lowered, compensatory reactions are stimulated by the SNS (increased peripheral resistance, tachycardia)
-if MAP is raises, compensatory reactions are stimulated by the PNS (bradycardia, more limited than SNS)

Question 17

where are ACh receptors

Answer 17

all preganglionic efferent autonomic fibers
somatic motor fibers to skeletal muscle
most PNS postganglionic and a few SNS postganglionic fibers

Question 18

NANC neurons

Answer 18

use NO as a neurotransmitter

parasympathetic, postganglionic neurons

Question 19

where are NE receptors

Answer 19

most postganglionic sympathetic fibers

a few sympathetic fibers release ACh

Question 20

adrenal medullary cells

Answer 20

analogous to postganglionic sympathetic neurons

release a mixture of epi and NE

Question 21

PNS effects on the eye

Answer 21

contraction of iris sphincter (miosis)
contraction of ciliary muscle (accommodation)
facilitates aqueous humor outflow

Question 22

PNS effects on cardiovascular system

Answer 22

reduce peripheral vascular resistance
direct effect is to slow heart rate
releases NO to relax smooth muscle

Question 23

PNS effects on respiratory system

Answer 23

contracts smooth muscle of bronchial tree
stimulates secretion of glands
exacerbates asthma

Question 24

PNS effects on GI tract

Answer 24

increases secretions (salivary, gastric, pancreatic, intestinal)
increases peristaltic activity
-contraction of longitudinal muscle
-relaxation of sphincters

Question 25

PNS effects on GU tract

Answer 25

contracts detrusor muscle relaxes trigone and sphincter muscles promotes voiding

Question 26

PNS effects on secretory glands

Answer 26

stimulation of thermoregulatory sweat glands

Question 27

production pathway of NE

Answer 27

``` conversion of tyrosine to DOPA is rate limiting -tyrosine hydroxylase DOPA converted to dopamine -DOPA carboxylase dopamine converted to NE -dopamine beta hydroxylase release is calcium dependent Uptake 1 transports catecholamines back into neuron (recycles) ```

Question 28

SNS effect on blood vessels

Answer 28

a receptors increase arterial resistance (pressure) B2 receptors relax venous smooth muscle (capacitance) -skin and splanchnic predominantly a, skeletal muscles more B2 (localization produces shift in blood flow from skin/gut to muscle if necessary) renin secretion stimulated by B receptors > longer term control of MAP

Question 29

SNS effects on heart

Answer 29

B1 receptor activity dominates -activation results in increased Ca2+ influx in cardiac cells (positive inotropy and chronotropy) AV conduction velocity increased refractory period decreased

Question 30

SNS effect on resp tract

Answer 30

relaxation of bronchial smooth muscle (B) | contraction of blood vessels (a) of upper resp mucosa can relieve nasal congestion

Question 31

SNS effect on GI tract

Answer 31

sphincter smooth muscle relaxation (B) longitudinal cell contraction (a) decreased PNS drive on enteric system

Question 32

SNS effect on GU tract

Answer 32

contraction of bladder base, urethral sphincter (a) relaxation of bladder wall smooth muscle (B) -promotes urinary retention

Question 33

SNS effect on exocrine glands

Answer 33

a receptors on apocrine (stress) glands -driven by SNS activity -sweating on palms, brow, upper lip M receptors on thermoregulatory sweat glands -driven by cholinergic SNS activity -sweating on body surface for evaporative cooling

Question 34

SNS effects on the eye

Answer 34

contraction of radial pupillary dilator muscles (a) -produces mydriasis increase aqueous humor secretion from ciliary epithelium (B)

Question 35

metabolic effects of SNS

Answer 35

``` shifts metabolism toward energy liberation and usage increases lipolysis enhances glycogenolysis increases glucose release increases insulin secretion ```

Question 36

dry mouth

Answer 36

reduced SNS/PNS excitatory innervation

Question 37

swallowing difficulty

Answer 37

reduced PNS mediated motility

Question 38

airway obstruction

Answer 38

PNS constriction due to loss of SNS dilation

Question 39

heart rate disturbances

Answer 39

SNS loss = brady | PNS loss = tachy

Question 40

gastric disturbances

Answer 40

SNS loss = hypermotility | PNS loss - hypomotility

Question 41

constipation

Answer 41

PNS loss

Question 42

fecal incontinence

Answer 42

SNS loss

Question 43

erectile dysfunction

Answer 43

PNS loss

Question 44

ejaculatory dysfunction

Answer 44

SNS loss

Question 45

urinary retention

Answer 45

PNS loss

Question 46

urinary incontinence

Answer 46

SNS loss

Question 47

pupil constriction

Answer 47

SNS loss

Question 48

pupil dilation

Answer 48

PNS loss

Question 49

loss of sweating

Answer 49

loss of SNS cholinergic

Question 50

orthostatic hypotension

Answer 50

inadequate SNS contraction of vasculature of lower extremities