autonomic nervous system Flashcards
receives sensory information and innervates skeletal muscle (voluntary)
- CNS and PNS components
somatic nervous system
innervates the viscera (organs)
- influences smooth muscle, cardiac muscle, and glands of skin and viscera (involuntary)
- CNS and PNS components
autonomic nervous system
“the boss” oversees all ANS activity
hypothalamus
“middle management”
brainstem autonomic nervous centers
“ordinary workers”
preganglionic and ganglionic neurons
collections of nerve cell bodies located in PNS
ganglia
uses motor neuron to go from CNS to skeletal muscle
somatic motor
uses motor neurons to go from CNS to target tissue
- consists of two neurons (preganglionic and ganglionic)
autonomic motor
cell body located in CNS
- its pre-ganglionic axon will synapse with the ganglionic neuron
pre-ganglionic neuron
synapses with the pre-ganglionic neuron (myelinated)
pre-ganglionic axon
cell body is located in autonomic ganglion (PNS)
it’s post-ganglionic axon will connect to the target tissue (effector)
ganglionic neuron
originates in lateral horns of T1-L2 region of spinal cord
- ganglia are located close to vertebral column
- “fight or flight” response/”emergency” situations
- exercise, excitement, emergency
- “mass activation” effect
sympathetic division (thoracolumbar)
- originates in some cranial nerves and parts of the sacral region of the spinal cord
- ganglia are located close to or within the target organ/tissue
-“rest and digest” response
- digestion, diuresis, defecation
- parasympathetic activity is usually discrete and localized
parasympathetic division (craniosacral)
- cranial components are part of CN’s III (Oculomotor), VII (Facial), IX (Glossopharyngeal), and X (Vagus)
- sacral components are from S2-S4 segments of the spinal cord (pelvic splanchnic nerves)
- “rest and digest”
location and characteristics of parasympathetic division
S2-S4 segments of the spinal cord (internal abdominal area)
pelvic splanchnic nerves
1) cell bodies of preganglionic neurons located in parts of certain cranial nerves, or in the sacral part of the spinal cord
2) preganglionic axons synapse in terminal or intramural (inside wall) ganglia which are located close to or in the organ being innervated
3) postganglionic axons travel from the ganglia to the target organ
parasympathetic division pathway
- originates in lateral horns of T1-L2 region of spinal cord (thoracolumbar)
- ganglia near the vertebral column
- “fight or flight”
sympathetic division location and characteristics
- sympathetic trunk
- white ramus
- gray ramus
- ganglia: paravertebral (next to vertebra; sympathetic trunk/chain) and prevertebral (collateral; located in front of vertebral column)
sympathetic division structures
1) cell bodies of preganglionic motor neurons in the lateral horns of T1-L2 segments of the spinal cord
preganglionic axons exit to spinal nerve and then go into the:
2) white ramus (runs from spinal nerve to sympathetic trunk)
3) sympathetic trunks (long chains of axons on either side of vertebral column)
- sympathetic trunk (paravertebral) ganglia
4) gray ramus (runs from the sympathetic trunk to a spinal nerve)
- sympathetic postganlionic axons
5) splanchnic nerves: preganglionic axons that do not synapse in the sympathetic trunk ganglia
6) prevertebral (collateral) ganglia
- splanchnic nerves synapse here
- located in front of the vertebral column
7) sympathetic postganglionic axons (travel directly to target organ)
sympathetic division pathway components
- all preganglionic axons (of the sympathetic division) enter the sympathetic trunk via the white ramus
the preganglionic axons exit through anterior roots to spinal nerve to white ramus to sympathetic trunk
sympathetic division pathways
some axons synapse in the sympathetic trunk and leave through the gray rami to spinal nerves out to the skin and blood vessels
spinal nerve pathway
some axons synapse in the sympathetic trunk and leave anteriorly to go to thoracic organs (and to head/neck)
postganglionic sympathetic pathway
some preganglionic axons leave the sympathetic trunk as splanchnic nerves go to prevertebral ganglia to synapse and head to abdominal and pelvic organs
splanchnic nerve pathway
