Autonomic NS Flashcards
What are the major functions of the autonomic nervous system (ANS)?
controls function of structures w/ smooth muscle, cardiac muscle and certain glands
What are the 3 subsystems involved in autonomic function?
sympathetic NS, parasympathetic NS, and Enteric NS
Describe the location of the sympathetic and parasympathetic nervous system.
sympathetic: thoracolumbar (T1-L3 @ lateral horns, and sympathetic trunk)
parasympathetic: craniosacral: CN 3,7,9,10; S2-S4
What are the major structural features of the somatic NS
reflex and higher level connections w/ CNS, afferent info>thalamus, source of descending pathways from the cerebral cortex
an efferent link has 1 neuron w/ chemical synapse @ effector tissue
What are the major structural features of the autonomic NS
reflex and higher level connections w/ CNS, send info to/from hypothalamus; 2 efferent neurons w/ ganglionic electrical synapses (gap junctions)
Define preganglionic and postganglionic fibers of the ANS. What are the major
physiological differences between the two? How does this differ between sympathetic
and parasympathetic systems?
preganglionic: light myelination (short in SNS, long in PNS)
postganglionic: gray-no myelination (long in SNS, short in PNS)
What are the major neurotransmitters at play in the ANS?
SNS: ACh (preganglionic)+ NE (postganglionic)
PNS: ACh (pre and postganglionic)
What bodily responses are associated with the sympathetic nervous system (SNS) and
fight-or-flight?
pupil dilation/ eyelid retraction, sweat, dry mouth/eyes, vasoconstriction to skin and gut, piloerection, bronchodilation, increased HR and CO, reduced digestion, increased glucagon and adrenaline
Describe the path taken by neurons exiting the spinal cord and heading to SNS efferent
structures.
T1-L3> head/thorax, lower thorax/upper lumbar>
A. sympathetic trunk>postganglionic @ same level if SC
B.sympathetic trunk> ascend or descend> more cranial/caudal ganglia
C. through trunk w.o synapsing> prevertebral ganglia
What are the major efferent targets of the SNS?
blood vessels and skin (grey comm matter)
viscera
lower extremities
What are the major efferent targets of the PSNS
EW nuclei superior and inferior salivary nuclei nucleus ambiguous Dorsal Motor Nucleus. of Vagus N Lat horns of S2-S4
Why are sympathetic responses longer than parasympathetic?
divergence of preganglionic neurons, longer unmyelinated postganglionic n
slower inactivation of NE in synapse
NE and Epi in blood
What structures are only innervated by the SNS?
sweat glands
erector pili muscles
most blood vessels
adrenal medulla
hat is paradoxical fear and how does it relate to the ANS?
accelerated PSNS response as our body basically just shuts down
what structures are involved in the control of ANS?
hypothalamus brainstem nuclei amygdala and other limbic structures medial prefrontal cortex insular cortex
