Ch 17: Autonomic Division Ch 17: Autonomic Division of NS of NS Compare and contrast the structures of Compare and contrast the structures of the sympathetic and the the sympathetic and the parasympathetic divisions, including parasympathetic divisions, including functions and neurotransmitters. functions and neurotransmitters. Show the levels of integration in the Show the levels of integration in the ANS, and compare these with the SNS. ANS, and compare these with the SNS.
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Ch 17: Autonomic Division of NSCh 17: Autonomic Division of NS
Compare and contrast the structures of the Compare and contrast the structures of the sympathetic and the parasympathetic sympathetic and the parasympathetic divisions, including functions and divisions, including functions and neurotransmitters.neurotransmitters.
Show the levels of integration in the ANS, and Show the levels of integration in the ANS, and compare these with the SNS.compare these with the SNS.
Overview of ANSOverview of ANS
Pathway for Visceral Motor Output Pathway for Visceral Motor Output
ANS has two antagonistic divisions:ANS has two antagonistic divisions:
1.1. SympatheticSympathetic
2.2. ParasympatheticParasympathetic
ANS output always involves two neurons ANS output always involves two neurons between spinal cord (CNS) and effector.between spinal cord (CNS) and effector.
Synapsing takes place in Synapsing takes place in gangliaganglia
Terminus for neuron #1, stimulates specialized Terminus for neuron #1, stimulates specialized 2nd order neurons with very short axons in 2nd order neurons with very short axons in adrenal medulla to release NT into blood stream adrenal medulla to release NT into blood stream (= hormones)(= hormones)
Epinephrine (adrenalin) ~ 80% and Epinephrine (adrenalin) ~ 80% and norepinephrine (noradrenalin)norepinephrine (noradrenalin)
Endocrine effects are longer lasting than nervous Endocrine effects are longer lasting than nervous system effects system effects
Differ from somatic Differ from somatic neuromuscular neuromuscular junctionsjunctions
VaricositiesVaricosities
Summary of Sympathetic DivisionSummary of Sympathetic Division
A. Neuron #1 is short, neuron #2 is longA. Neuron #1 is short, neuron #2 is long
B. Synapsing occurs in prevertebral chain ganglia or B. Synapsing occurs in prevertebral chain ganglia or paravertebral collateral gangliaparavertebral collateral ganglia
C. Neuron #1 releases Ach, usually neuron #2 C. Neuron #1 releases Ach, usually neuron #2 releases NEreleases NE
D. Prepares for emergency action, excitatory to D. Prepares for emergency action, excitatory to many organs, inhibitory to others ( digestive for many organs, inhibitory to others ( digestive for example)example)
E. Effects very widespread and somewhat persistentE. Effects very widespread and somewhat persistent
Para – SympatheticPara – SympatheticDivisionDivision
CraniosacralCraniosacral division division
Preganglionic neurons (cell bodies) Preganglionic neurons (cell bodies) located in brain stem & sacral segments of located in brain stem & sacral segments of spinal cordspinal cord
Ganglionic neurons (cell bodies) in ganglia Ganglionic neurons (cell bodies) in ganglia near target organs: near target organs: Intramural gangliaIntramural ganglia
Effects of parasympathetic division ?Effects of parasympathetic division ?
Summary of Parasympathetic DivisionSummary of Parasympathetic Division
A. Neurons #1 are long, come from the A. Neurons #1 are long, come from the brain stem or sacral spinal cord, run brain stem or sacral spinal cord, run with the spinal or pelvic nerves and with the spinal or pelvic nerves and produce ACh. produce ACh.
B. Neurons #2 are short, produce ACh, B. Neurons #2 are short, produce ACh, and may be either excitory or and may be either excitory or inhibitory.inhibitory.
Anatomy of Dual InnervationAnatomy of Dual Innervation
Each organ receives Each organ receives innervation from innervation from sympathetic and sympathetic and parasympathetic fibersparasympathetic fibers
Fibers of both divisions meet Fibers of both divisions meet & commingle at plexuses & commingle at plexuses (fig 17-9) to innervate (fig 17-9) to innervate organs close to those organs close to those centerscenters
Names of plexuses derived Names of plexuses derived from locations or organs from locations or organs involvedinvolved