Introduction to the Autonomic Nervous System

Question 1

autonomic nervous system (ANS)

Answer 1

motor (efferent) component of visceral nervous system

concerned w/ automatic & involuntary regulation of all visceral structures of body

Question 2

ANS regulates visceral activities by balancing ___ actions of two systems ___ & ___

Answer 2

opposing

sympathetic

parasympathetic

Question 3

sympathetic system

Answer 3

preparation of body for quick action

“fight or flight”

ex. increased heart rate
elevation of blood pressure
increased blood flow to skeletal muscles
dilation of pupils of eyes
inhibition of digestive system & other nonessential activities

Question 4

parasympathetic system

Answer 4

conservation of energy

“rest & digest”

ex. decreased heart rate
decreased blood pressure
decreased blood flow to skeletal muscles
constriction of pupils of eyes
increased activity of digestive system & other viscera

Question 5

opposing effects of sympathetic & parasympathetic systems possible b/c of ___ released at target tissues

sympathetic: ___
parasympathetic: ___
exception: ___

Answer 5

neurotransmitters

norepinephrine

acetylcholine

sweat glands of skin are innervated by sympathetic fibers which release acetylcholine instead of norepinephrine (no parasympathetic counterpart)

Question 6

stimulation of sympathetic nervous system leads to ___

stimulation of parasympathetic system leads to ___

Answer 6

widespread & long lasting effects (fibers connected all over the place)

more localized & shorter lasting effects

Question 7

both sympathetic & parasympathetic portions of ANS consist of ___ chains

first (___) has its cell body ___

second (___) has its cell body ___

Answer 7

two-neuron

preganglionic neuron, in brain stem or spinal cord

postganglionic neuron, outside of CNS often in a collection of nerve cells called a ganglion

Question 8

preganglionic fibers of both sympathetic & parasympathetic nervous systems are ___ & release ___ at their terminals

Answer 8

myelinated

acetylcholine

Question 9

postganglionic fibers of both sympathetic & parasympathetic nervous systems are ___ & release ___ for sympathetic & ___ for parasympathetic (exception: ___)

Answer 9

unmyelinated

norepinephrine

acetylcholine

postganglionic sympathetic fibers innervating sweat glands of skin release acetylcholine at terminals (no parasympathetic fibers go to sweat glands)

Question 10

sympathetic system:

preganglionic neurons are located in the ___ of the spinal cord from ___ to ___ (___)

Answer 10

lateral gray horns

T1 - L2/L3

thoracolumbar outflow

Question 11

sympathetic system:

preganglionic axons (fibers) traverse the ___ roots of the spinal nerves & enter the ___ of a spinal nerve

the preganglionic axons then exit the ___ as a bundle called the ___ and enter the ___

Answer 11

ventral, ventral ramus

ventral ramus, white communicating ramus, sympathetic trunk

Question 12

sympathetic system:

the sympathetic trunks consist of ___ (___) connected by bundles of intervening ___, the structure appearing like beads on a string

the trunk extends from ___ to ___ where they’re connected by a slight enlargement, ___

Answer 12

sympathetic ganglia (paravertebral ganglia), preganglionic sympathetic fibers

C1 - tip of coccyx, ganglion impar

Question 13

sympathetic system:

each sympathetic trunk consists of 3 ___ sympathetic ganglia (___, ___, ___), 11-12 ___ ganglia, 4-5 ___ ganglia, & 5 or less ___ ganglia

the ___ cervical ganglion is often fused w/ the ___ forming the ___

Answer 13

cervical - superior, middle, inferior

thoracic

lumbar

sacrococcygeal

inferior, thoracic, stellate ganglion

Question 14

sympathetic system:

preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunk: (1)

synapse in corresponding ganglia at ___ level

postganglionic fibers then rejoin spinal nerve via ___ that consist of ___ postganglionic sympathetic fibers

Answer 14

that

gray communicating ramus

unmyelinated

Question 15

sympathetic system:

preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunk: (2)

___ or ___ the trunk & synapse at a ___ level

source of preganglionic fibers for ganglia above ___ or below ___

Answer 15

ascend, descend

different

T1, L2

Question 16

white communicating rami are only found from ___ to ___

gray rami are found at ___ levels

Answer 16

T1 - L2/L3

all

Question 17

sympathetic system:

preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunk: (3)

pass through sympathetic trunk ganglia ___

travel via ___, ___, and ___ ___ nerves to ___ (___) ganglia

Answer 17

without synapsing

thoracic, lumbar, & sacral splanchnic

prevertebral (collateral)

Question 18

sympathetic system:

preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunk: (4)

pass through ___ ganglia (___ & ___)

synapse w/ ___ cells of the ___ (modified sympathetic ganglion cells)

Answer 18

all (paravertebral, prevertebral)

chromaffin, adrenal medulla

Question 19

splanchnic nerve

exception

Answer 19

sympathetic nerves supplied to visceral organs

pelvic splanchnic - parasympathetic

Question 20

preganglionic sympathetic fibers that provide autonomic innervation within the head, neck, body wall, limbs, & thoracic cavity follow one of the ___ courses after entering the sympathetic trunk

Answer 20

first two

Question 21

preganglionic sympathetic fibers involved in innervating viscera within the abdominopelvic cavity follow the ___ course

they pass through the ganglia of the sympathetic trunk ___ synapsing as they travel via the ___, ___, & ___ ___ nerves & eventually synapse in the ___ (___) ganglia

Answer 21

third

without

thoracic, lumbar, & sacral splanchnic

prevertebral (collateral)

Question 22

preganglionic sympathetic fibers destined for the suprarenal gland travel through the ___ ___ nerves & pass through the ___ (___) ganglia ___ synapsing

they terminate on the ___ cells of the ___ ___ which are modified postganglionic sympathetic neurons

the ___ cells of the ___ ___ release ___ & ___ into the bloodstream producing a widespread sympathetic response

Answer 22

thoracic splanchnic

prevertebral (collateral), without

chromaffin, suprarenal medulla

chromaffin, suprarenal medulla, epinephrine, norepinephrin

Question 23

postganglionic sympathetic fibers destined for distribution within the neck, body wall, & limbs enter ___ sets of spinal nerves

they pass from the sympathetic trunk (paravertebral) ganglia to adjacent ___ of spinal nerves via ___

they enter all branches of the nerves including dorsal rami (for back) to simulate:

• contraction of ___ ___ (vasomotor fibers)
• contraction of ___ ___ muscles associated w/ hair follicles (pilomotor fibers resulting in “goose bumps”)
• secretion of ___ ___ (sudomotor fibers)

Answer 23

all 31

ventral rami, gray communicating rami

blood vessels
arrector pili
sweat glands

Question 24

postganglionic sympathetic fibers that perform functions in the head all have their cell bodies in the ___*

they reach their destinations as a ___ plexus of nerves following the branches of the ___ arteries*

Answer 24

superior cervical ganglion

periarterial, carotid

Question 25

preganglionic parasympathetic neurons have their cell bodies in the ___ levels of the spinal cord (___ ___)

Answer 25

brainstem & S2 - S4

craniosacral outflow

Question 26

cell bodies of parasympathetic postganglionic neurons are usually located in minute ganglia ___ the organs innervated

Answer 26

close to or within

Question 27

there is ___ parasympathetic innervation to the limbs & ___ innervation to the body wall (erectile tissue in male & female genitalia)

Answer 27

no

one

Question 28

the only four pairs of parasympathetic ganglia w/ specific names & located in the head region

Answer 28

ciliary ganglion - orbital cavity

pterygopalatine ganglion - pterygopalatine fossa

otic ganglion - infratemporal fossa

submandibular ganglion - floor of mouth

Question 29

myelinated preganglionic parasympathetic fibers which exit the brain stem & are carried on four cranial nerves

Answer 29

oculomotor nerve - CN III

facial nerve - CN VII

glossopharyngeal nerve - CN IX

vagus nerve - CN X (no innervation in head, wanders all over the place, originates from brain stem)

Question 30

distribution of preganglionic parasympathetic fibers within head

Answer 30

oculomotor nerve (CN III) - ciliary ganglion

facial nerve (CN VII) - pterygopalatine ganglion, submandibular ganglion

glossopharyngeal nerve (CN IX) - otic ganglion

Question 31

preganglionic parasympathetic fibers of vagus nerve end on minute collections of parasympathetic ganglion cells (postganglionic parasympathetic neurons) distributed throughout the ___, ___, & most of the ___

it provides innervation to the following:

• all ___ viscera
• ___ tract from esophagus to left colic flexure (___ & ___ derivatives)

note: vagus nerves carry approximately ___% of the body’s preganglionic parasympathetic fibers

Answer 31

neck, thorax, abdomen

thoracic

gastrointestinal, (foregut & midgut)

75%

Question 32

preganglionic parasympathetic fibers originating from cell bodies in S2 - S4 spinal cord segments exit the spinal cord by way of the ___ & ___ of sacral spinal nerves S2, S3, & S4

these are called the ___

Answer 32

ventral roots

ventral rami

pelvic splanchnic nerves

Question 33

the pelvic splanchnic nerves transmit their preganglionic ___ fibers to minute collections of ___ ganglion cells (postganglionic ___ neurons) on or close to ___ & ___ viscera

the pelvic splanchnic nerves begin innervating structures where the ___ nerves leave off:

• ___ colon, ___ colon, ___ (hindgut derivatives)
• all ___ organs

Answer 33

parasympathetic, parasympathetic, parasympathetic

abdominal & pelvic

vagus

descending, sigmoid, rectum

pelvic

Question 34

the parasympathetic system is much more ___ in its distribution than they sympathetic system

the parasympathetic system distributes only to the ___, ___ of the trunk, & ___ tissues

w/ the exception of the external genitalia, it does not reach the ___ or the ___

Answer 34

restricted

head, visceral cavities, erectile

body wall, limbs