Introduction to the Autonomic Nervous System Flashcards
autonomic nervous system (ANS)
motor (efferent) component of visceral nervous system
concerned w/ automatic & involuntary regulation of all visceral structures of body
ANS regulates visceral activities by balancing ___ actions of two systems ___ & ___
opposing
sympathetic
parasympathetic
sympathetic system
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
parasympathetic system
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
opposing effects of sympathetic & parasympathetic systems possible b/c of ___ released at target tissues
sympathetic: ___
parasympathetic: ___
exception: ___
neurotransmitters
norepinephrine
acetylcholine
sweat glands of skin are innervated by sympathetic fibers which release acetylcholine instead of norepinephrine (no parasympathetic counterpart)
stimulation of sympathetic nervous system leads to ___
stimulation of parasympathetic system leads to ___
widespread & long lasting effects (fibers connected all over the place)
more localized & shorter lasting effects
both sympathetic & parasympathetic portions of ANS consist of ___ chains
first (___) has its cell body ___
second (___) has its cell body ___
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
preganglionic fibers of both sympathetic & parasympathetic nervous systems are ___ & release ___ at their terminals
myelinated
acetylcholine
postganglionic fibers of both sympathetic & parasympathetic nervous systems are ___ & release ___ for sympathetic & ___ for parasympathetic (exception: ___)
unmyelinated
norepinephrine
acetylcholine
postganglionic sympathetic fibers innervating sweat glands of skin release acetylcholine at terminals (no parasympathetic fibers go to sweat glands)
sympathetic system:
preganglionic neurons are located in the ___ of the spinal cord from ___ to ___ (___)
lateral gray horns
T1 - L2/L3
thoracolumbar outflow
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 ___
ventral, ventral ramus
ventral ramus, white communicating ramus, sympathetic trunk
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, ___
sympathetic ganglia (paravertebral ganglia), preganglionic sympathetic fibers
C1 - tip of coccyx, ganglion impar
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 ___
cervical - superior, middle, inferior
thoracic
lumbar
sacrococcygeal
inferior, thoracic, stellate ganglion
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
that
gray communicating ramus
unmyelinated
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 ___
ascend, descend
different
T1, L2
white communicating rami are only found from ___ to ___
gray rami are found at ___ levels
T1 - L2/L3
all
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
without synapsing
thoracic, lumbar, & sacral splanchnic
prevertebral (collateral)
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)
all (paravertebral, prevertebral)
chromaffin, adrenal medulla
splanchnic nerve
exception
sympathetic nerves supplied to visceral organs
pelvic splanchnic - parasympathetic
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
first two
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
third
without
thoracic, lumbar, & sacral splanchnic
prevertebral (collateral)
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
thoracic splanchnic
prevertebral (collateral), without
chromaffin, suprarenal medulla
chromaffin, suprarenal medulla, epinephrine, norepinephrin
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)
all 31
ventral rami, gray communicating rami
blood vessels
arrector pili
sweat glands
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*
superior cervical ganglion
periarterial, carotid
preganglionic parasympathetic neurons have their cell bodies in the ___ levels of the spinal cord (___ ___)
brainstem & S2 - S4
craniosacral outflow
cell bodies of parasympathetic postganglionic neurons are usually located in minute ganglia ___ the organs innervated
close to or within
there is ___ parasympathetic innervation to the limbs & ___ innervation to the body wall (erectile tissue in male & female genitalia)
no
one
the only four pairs of parasympathetic ganglia w/ specific names & located in the head region
ciliary ganglion - orbital cavity
pterygopalatine ganglion - pterygopalatine fossa
otic ganglion - infratemporal fossa
submandibular ganglion - floor of mouth
myelinated preganglionic parasympathetic fibers which exit the brain stem & are carried on four cranial nerves
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)
distribution of preganglionic parasympathetic fibers within head
oculomotor nerve (CN III) - ciliary ganglion
facial nerve (CN VII) - pterygopalatine ganglion, submandibular ganglion
glossopharyngeal nerve (CN IX) - otic ganglion
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
neck, thorax, abdomen
thoracic
gastrointestinal, (foregut & midgut)
75%
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 ___
ventral roots
ventral rami
pelvic splanchnic nerves
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
parasympathetic, parasympathetic, parasympathetic
abdominal & pelvic
vagus
descending, sigmoid, rectum
pelvic
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 ___
restricted
head, visceral cavities, erectile
body wall, limbs
