Autonomic Nervous System

Question 1

the autonomic nervous system innervates:

Answer 1

1. smooth muscle in organs and blood vessels
2. cardiac muscle
3. glands

Question 2

part of the ____ division of the peripheral nervous system

Answer 2

motor division

Question 3

autonomic motor systems vs. single somatic motor axon

Answer 3

autonomic motor system: thinly myelinated preganglionic neuron, unmyelinated postganglionic neuron, pre- and postganglionic neurons synapse in a ganglion

somatic motor system: axons are typically well myelinated, conduct impulses more rapidly, have one axon that extends from the CNS to the muscle directly

Question 4

sympathetic nervous system effects

Answer 4

increases: heart rate, breathing rate, blood and oxygen to skeletal muscles
dilates: pupils and airways
inhibits: motility of the digestive and urinary tracts
stimulates: sweat glands, arrector pili muscles

Question 5

parasympathetic nervous system effects

Answer 5

conserves energy
heart rate and breathing rate remain normal
normal motility of digestive tract, normal digestive enzyme production
pupils are constricted

Question 6

anatomical differences: sympathetic vs. parasympathetic

Answer 6

different regions of CNS
length of postganglionic axon fibers
branching of postganglionic axon fibers
neurotransmitter released by postganglionic axons

Question 7

regions of CNS: sympathetic vs. parasympathetic

Answer 7

sympathetic = thoracolumbar
parasympathetic = craniosacral

Question 8

length of postganglionic axon fibers: sympathetic vs. parasympathetic

Answer 8

sympathetic - usually longer, ganglia are closer to CNS

parasympathetic - usually shorter, ganglia are closer to viscera

Question 9

branching of postganglionic axon fibers: sympathetic vs. parasympathetic

Answer 9

sympathetic - may be highly branched

parasympathetic - have few branches

Question 10

neurotransmitter released by postganglionic axon: sympathetic vs. parasympathetic

Answer 10

sympathetic - norepinephrine (adrenergic)

parasympathetic - acetylcholine (cholinergic)

Question 11

parasympathetic: cranial outflow

Answer 11

comes from CN III (oculomotor), CN VII (facial), CN IX (glossopharyngeal), CN X (vagus) in brainstem
innervates: organs of the head, neck, thorax, most of abdomen
cell bodies of preganglionic cranial nerves located in cranial nerve nuclei in the brainstem
ganglionic cell bodies located near viscera/organs/tissues being innervated
path of vagus nerve (CN X) sends branches throughout parasympathetic autonomic nerve plexuses

Question 12

cranial nerves contributing to parasympathetic outflow

Answer 12

CN III (oculomotor)
CN VII (facial)
CN IX (glossopharyngeal)
CN X (vagus)

Question 13

parasympathetic cranial outflow innervates

Answer 13

organs of the head, neck, thorax, most of abdomen

Question 14

parasympathetic: sacral outflow

Answer 14

S2-S4
comes from visceral motor region of ventral gray matter of spine
innervates: organs of pelvis and lower abdomen
stimulates urination, defecation, and erection
preganglionic cell bodies located in ventral gray matter of spine (visceral motor region)
axons run in ventral roots to ventral rami, form pelvic splanchnic nerves
run through the inferior hypogastric (pelvic) plexus

Question 15

sympathetic division

Answer 15

issues from T1-L2 (thoracolumbar)
preganglionic fibers emerge from the lateral gray horn of the spinal cord
supplies visceral organs and structures of superficial body regions
contains more ganglia than the parasympathetic division

Question 16

sympathetic trunk ganglia

Answer 16

located on both sides of the vertebral column
linked by short nerves into sympathetic trunks
also called chain or paravertebral ganglia

Question 17

sympathetic neurons in the thoracolumbar spinal cord send motor axons through trunk ganglia via this sequence:

Answer 17

preganglionic axon (thinly myelinated) - ventral root, ventral ramus of spinal nerve, white ramus communicans, associated sympathetic trunk ganglion
postganglionic axon (unmyelinated) - gray ramus communicans, ventral ramus of spinal nerve

Question 18

white rami communicans

Answer 18

contain lightly myelinated preganglionic fibers traveling to sympathetic trunk ganglia

Question 19

gray rami communicans

Answer 19

contain unmeylinated postganglionic fibers traveling from ganglia to peripheral structures

Question 20

sympathetic preganglionic axons follow one of three pathways

Answer 20

1. synapses with a postganglionic neuron at the same level and exits on a spinal nerve at that level
2. axon ascends or descends in the sympathetic trunk to synapse in another ganglion
3. axon does not synapse in the sympathetic trunk but instead passes through and exits in a splanchnic nerve and synapses in a collateral ganglion from which a postganglionic axon extends to the visceral ganglions

Question 21

three sympathetic preganglionic axon pathways (short version)

Answer 21

1. synapses and exits on spinal nerve at same level
2. axon ascends or descends to another ganglion
3. axon exits in a splanchnic nerve and synapses in a collateral ganglion

Question 22

splanchnic nerves

Answer 22

nerves of the sympathetic nervous system that innervate viscera and blood vessels

Question 23

collateral (prevertebral) ganglia differ from sympathetic trunk ganglia in 3 ways

Answer 23

1. unpaired, not segmentally arranged
2. occur only in pelvis and abdomen
3. lie anterior to the vertebral column

Question 24

sympathetic collateral ganglia

Answer 24

celiac
inferior mesenteric
superior mesenteric
inferior hypogastric (pelvic)

Question 25

sympathetic ganglia (7)

Answer 25

``` inferior cervical superior cervical middle cervical celiac inferior mesenteric superior mesenteric hypogastric ```

Question 26

sympathetic pathways to the head

Answer 26

preganglionic fibers originate T1-T4 fibers ascend in the sympathetic trunk and synapse in superior cervical ganglion postganglionic fibers associate with eye, lacrimal gland, nasal mucosa, salivary glands

Question 27

sympathetic pathways to the head: summary

Answer 27

origin: T1-T4 ganglia: superior cervical endpoint: eye, lacrimal gland, nasal mucosa, salivary glands

Question 28

sympathetic pathways to the thoracic region

Answer 28

preganglionic fibers originate T1-T6 some fibers synapse in nearest sympathetic ganglion and the nearest postganglionic fibers run to the heart, lungs, and esophagus

Question 29

sympathetic pathways to the thoracic region: summary

Answer 29

origin: T1-T6 endpoint: heart, lungs, esophagus

Question 30

sympathetic pathways to abdominal organs

Answer 30

preganglionic fibers originate T5-L2 pass through adjacent sympathetic ganglia then travel in splanchnic nerves synapse in collateral ganglia (celiac and superior mesenteric) in abdomen

Question 31

sympathetic pathways to abdominal organs: summary

Answer 31

origin: T5-L2 ganglia: celiac, superior mesenteric

Question 32

sympathetic pathways to pelvic organs

Answer 32

preganglionic fibers originate in spinal cord from T10-L3 some preganglionic fibers pass directly to autonomic plexuses and synapse in collateral ganglia, inferior mesenteric or pelvic ganglia postganglionic fibers go from these plexuses to the bladder, reproductive organs, and distal large intestine

Question 33

sympathetic pathways to pelvic organs: summary

Answer 33

origin: T5-L2 ganglia: inferior mesenteric and pelvic (hypogastric) endpoint: bladder, reproductive organs, distal large intestine

Question 34

role of the adrenal medulla in the sympathetic division

Answer 34

major organ of the sympathetic nervous system constitutes largest sympathetic ganglia secretes largest quantities of epinephrine and norepinephrine stimulated to secrete by preganglionic sympathetic fibers carried in thoracic splanchnic nerve

Question 35

epinephrine production stimulated by

Answer 35

preganglionic sympathetic fibers carried in thoracic splanchnic nerve travel to adrenal medulla

Question 36

CNS control of ANS

Answer 36

``` cerebral frontal cortex hypothalamus amygdala brainstem (reticular formation) spinal cord ```

Question 37

cerebral frontal cortex: control of ANS

Answer 37

people can exert some conscious control over some autonomic functions by developing control over their thoughts and emotions feelings of calm achieved during meditation are associated with the cerebral cortex enhancing parasympathetic centers in the hypothalamus voluntary recall of a frightful experience can activate the sympathetic system via the amygdala

Question 38

amygdala: control of ANS

Answer 38

main limbic region for emotions communication with the hypothalamus and periaqueductal gray matter can stimulate sympathetic activity (especially previously learned fear-related behavior)

Question 39

hypothalamus: control of ANS

Answer 39

main integration center of the autonomic nervous system medial and anterior parts direct parasympathetic function lateral and posterior parts direct sympathetic function

Question 40

reticular formation: control of ANS

Answer 40

medulla oblongata - cardiac center, vasomotor, digestive activities periaqueductal gray matter - exerts sympathetic fear response

Question 41

spinal cord: control of ANS

Answer 41

``` influences visceral spinal reflexes: urination reflex defecation reflex erection reflex ejaculation/orgasm reflex ```

Question 42

Raynaud's disease

Answer 42

characterized by constriction of blood vessels provoked by exposure to cold or by emotional stress disorder of the autonomic nervous system

Question 43

hypertension

Answer 43

high blood pressure | can result from overactive sympathetic vasoconstriction