Autonomic Nervous System Flashcards
ANS primary function
primary function
-acts to maintain the internal environment within the limits compatible with life
ANS
-responsds to..
responds to both internal and external changes and makes appropriate homeostatic adjustments
ANS
- controlled by…
- coordinated with…
controlled by the hypo and through it is coordinated with the CNS, endocrine and immune systems
ANS “final common pathway” or “LMN”
-how is it different from the somatic motor system?
consists of a “two neuron chain” LMN organization
ANS “two neuron chain”
- consists of…
- how do they get their names
preganglionic neuron
-has a cell body located within the CNS
postganglionic neuron
-has a cell body located in a peripheral ganglion
where do the following synapse
- preganglionic neurons
- postganglionic neurons
pre
-post neurons
post
-ANS target tissues
what are ANS target tissues?
smooth muscle
cardiac muscle
glands
ANS major divisions
-location of each
sympathetic
-thoracolumbar
parasympathetic
-craniosacral
sympathetic nervous system is organized with…
preganglionic cell bodies
postganglionic cell bodies
SNS preganglionic cell bodies
-located in…
the intermediolateral cell column (lateral horn) of spinal cord levels T1-L2 (thoracolumbar)
SNS preganglionic cells
- axon descriptions
- neurotransmitter
short myelinated axon (type III) directed toward peripheral sympathetic chain ganglion
neurotransmitter
-Ach (nicotinic)
SNS postganglionic cell bodies
-location
paravertebral ganglion located parallel to the spinal cord along a paravertebral chain associated with the ventral roots of spinal nerves T1-L2
also located in the cervical region and as prevertebral ganglion
SNS postganglionic cells
- axon descriptions
- neurotransmitter
long unmyelinated axons (type IV) travel as components of peripheral nerves to target organs
neuro
-norepinephrine
SNS postganglionic cells
-how is norepinephrine released?
adrenal medulla receives preganglionic innervation
-activates and releases norepinephrine hormonally
PSNS preganglionic cell bodies
-location
located in nuclei associated with CN III, VII, IX, X
located in the intermediolateral cell column of spinal cord levels S2-S4 (craniosacral)
PSNS preganglionic cells
- axon description
- neurotransmitter
long myelinated axon (type III) directed toward peripheral ganglion
neuro
-ACh (nicotinic)
PSNS postganglionic cell bodies
-location
ganglion located near the target organ or within the wall of the target organ
PSNS postganglionic cell bodies
- axan description
- neurotransmitter
short unmyelinated axons (type IV)
neuro
-ACh (muscarinic)
ANS functional interactions: convergence-divergence
-explain
preganglionic axon can synapse on more than one postganglionic cell body resutling in divergence
OR
several preganglionic axons can synapse on a single postganglionic cell body resulting in convergence
which of the ANS systems displays a greater degree of divergence
-what is the resut?
SNS
accounts for mass action effect of sympathetic activity
as a “final common pathway,” the innervation of smooth muscles, cardiac muscles, and glands establishes and maintains _____ similar to _____
establishes and maintains “tone” similar to the tone noted in our somatic extrafusal muscles
smooth muscles of capillary beds are controlled by _____ “tone”
sympathetic
how is blood flow controlled in the capillary beds of the peripheral vascular system
they receive no parasympathetic innervation
an increase or decrease in sympathetic activity changing the “tone” of precapillary sphincters results in changes of flow through capillary beds
muscles of the iris receive _____ innervation
-result of this
both para and sympathetic innervation
-exhibit both para and sympathetic tone
constrictor pupillae
- _____ innervation
- location of responsible cell bodies
- -this is part of…
para
Edinger Westphal nucleus
-part of the Oculomotor complex CNIII)
dilator pupillae
- _____ innervation
- -location of preganglionic cells
sympathetic innervation
preganglionic cells located in the lateral horn of spinal cord segments T1-T2
loss of para innervation results in what at the eye?
dilation of the pupil due to unossosed sympathetic tone
Horner’s Syndrome
- due to…
- results in…
due to loss of sympathetic innervation to the face
results in a constricted pupil due to unopposed para tone
Horner’s Syndrome
- also marked by…
- cause of each
flushed face
-lack of constriction of the precapillary sphincter
dry face
-lack of sympathetic drive for gland activity
bladder control and spinal circuitry
-_____ muscles are controlled by _____
detrussor and trigone (internal sphincter) are controlled by balanced sympathetic (T11-L2) and parasympathetic (S1-S2) control
bladder control and spinal circuitry
-SNS role
bias results in slight relaxation of detrussor muscle and ocntraction of the trigone for bladder filling
bladder control and spinal circuitry
-PSNS role
bias results in contraction of the detrussor and relaxation of the trigone
bladder control and spinal circuitry
-PSNS control can be facilitated or inhibited by…
cortical control
micturation
- what is it
- initiated by…
- after initiated, where does the signal go and what does it do?
urination
initiated by stretch receptors in the bladder wall (especially trigone area) that enter the cord and then are sent back over PSNS for contraction of detrussor muscle and relaxation of trigone (high PSNS bias)
during filling, there is high _____ bias
SNS
bladder control and spinal circuitry
-results of cord lesions that leave the sacral levels intact
will leave the micturition reflex intact
micturition will no longer be under the influence of descending cortical control
autonomic dysreflexia
- caused by
- results in…
caused by complete transection of the cord at cervical or upper thoracic levels
results in an increase in sympathetic outflow due to complete loss of brainstem and cortical control
autonomic dysreflexia
-result of sympathetic outflow
with either somatic or visceral stimulation that reaches sympathetic regions of the cord, an increase in sympathetic firing occurs
-i.e. increase in heart rate, vasoconstriction, that results in a rapid (dangerous) increase in BP
headache also associated with this clinical scenario
how does the limbic system influence the ANS?
-what is its function
limbic has a powerful influence on the hypo, thus on the ANS
this extensive connectional interaction is used for
-production of social behavior
-can color perceptions
relationship between the ANS and limbic system in the generation of emotion
for the generation of emotion, the interface between the amygdala and the ANS is “collected” in the orbitofrontal part of cortex
hypothalamus
-serves as the “_____ of the ANS”
UMNs
why is the hypothalamus seen to house the UMNs of the ANS?
descending information from the hypo, via RF pathways, influence both divisions of the ANS
lesions of these descending influences may result in ANS disturbances
which portions of the hypothalamus act as parasympathetic activating regions
anterior and ventromedial hypothalamic regions
which portions of the hypothalamus act as sympathetic activating regions
posterolateral and ventromedial
ventromedial hypothalamus
-how does it act on both the SNS and PSNS components?
through separate nuclei
lesions of ventromedial (PSNS) regions result in…
vasoconstriction = hyperthermia or an increase in body core temperature and an inability to reduce sympathetic tone
hypothalamus involved in motor expression of _____, but has no role in the _____ which accompany these behaviors
motor expression of -rage -fear -aversion no role in the feelings or emotions
patterns of expression and behavior are subject to…
limbic system influence (where emotions arise)
in part to associated changes in visceral system function (ANS)
rage
-function
defensive behavior
rage
-what happens when you activate medial parts of the hypothalamus (in cats)
defensive behaviors -hissing and extension of claws ANS components -pupil dilation -increased HR and piloerection
what is piloerection
hair standing on end
activation of the medial parts of the amygdala
- what occurs
- anatomical relationship that allows this to occur
medial parts of amygdala send projections in the septal region and medial hypothalamus
facilitates the defensive rage behavior, including the ANS components
activation of the medial parts of the amygdala
-function of amygdala and hypothalamus in facilitating the response
amygdala
-helps with the emotional component of the rage behavior
hypo
-serves to activate the motor (ANS) manifestation of rage
in humans, what area can be damaged that can result in rage behaviors that are elicited by innocuous (not normally disturbing) stimuli
-what else could cause these behaviors
temporal lobe limbic structures
seizure foci in amygdala and/or hippocampus
effect of lesion above C4 on somatic (breathing) and autonomic function
breathing requires artificial support
autonomic dysreflexia, poor thermoregulation, orthostatic hypotension
lack voluntary control of bladder, bowels, sexual function
effect of lesion above T6 on somatic (breathing) and autonomic function
-difference from C4 or higher lesion
difference
-adequate descending control of phrenic nerve, intercostals, and abdominal muscles (breathing near normal, lower intercostals and abdominals without UMN; no descending control)
thermoregulation, orthostatic hypotension
lack voluntary control of bladder, bowels, sexual function
effect of lesion above S2 on somatic (breathing) and autonomic function
-difference from T6 or higher lesion
difference
-adequate descending sympathetic control for BP and thermal regulation
adequate breathing (normal)
lack voluntary control of bladder, bowels, sexual function
effect of lesion of S2-S4 on somatic (breathing) and autonomic function
-difference from the other 3 lesion sites
lack of reflexive control of pelvic organs
breathing normal
