Anatomy and Cell Biology 3319 Lecture Notes - Lecture 15: Autonomic Nervous System, Parasympathetic Nervous System, Anterior Ramus Of Spinal Nerve
1 May 2018
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Lecture 015: Autonomic Nervous System
Autonomic Nervous System is composed of:
● Sympathetic Nervous System
○ Fight or flight
● Parasympathetic Nervous System
○ Rest and digest
Learning Outcomes
● Compare somatic vs autonomic nervous system
● Discuss the parasympathetic nervous system
○ Function
○ Organization
○ Pathway
● Discuss the sympathetic nervous system
● Clinically apply knowledge of autonomic nervous system
Somatic NS
Autonomic NS
● Innervate the skeletal muscle
(voluntary control)
● Involves only one neuron
○ CNS -> effector muscle
● Thick and myelinated
○ Fast conduction
● Innervates the smooth and cardiac
muscle, glands, and visceral organs
(involuntary for the most parts)
● Involves two neurons
○ Preganglionic
■ Thinly myelinated
○ Postganglionic
■ Not myelinated
○ Overall speed of conduction is
slower than the somatic NS
○ CNS -> Preganglionic ->
Postganglionic -> effector
● Acetylcholine (ACh)
○ preganglionic neuron
○ Parasympathetic
postganglionic neuron
● Epinephrine/noradrenaline (NE)
○ Sympathetic postganglionic
neuron
Key Concepts
● Dorsal rootlets: sensory
● Ventral rootlets: motor innervation (including ANS)
● Dorsal and ventral rootlets join into the spinal nerve then split into the dorsal and ventral
rami (mixed nerves)
Parasympathetic: Overview
find more resources at oneclass.com
find more resources at oneclass.com
● Want to converse energy during rest, gear energy towards essential functions like
digestion, urination, and defecation
○ Heart rate and respiratory rate are low
○ GI is digesting food
○ Pupils are constricted for close vision
● Also called: the Craniosacral division
● Have long preganglionic fibers and short postganglionic neurons (close to the organ)
Parasympathetic: Pathway
Cranial Outflow Part 1: innervation of the head
● Preganglionic fibers start from the brainstem runs with the cranial nerve
○ Oculomotor, facial, glossopharyngeal nerves
● Will synapse with the postganglionic on the head/neck region
○ Runs with the trigeminal nerves to:
■ Eyes for pupil constriction
■ Lacrimal and nasal gland for mucus secretion
■ Submandibular and sublingual glands for salivation secretion
Cranial Outflow Part 2: innervation of the organs/trunk
● Preganglionic fiber starts from the brainstem and runs with the vagus nerve
○ Fiber enters a plexuses (a concentration of nerves within a region, has
representation from both division of the autonomic nervous system)
■ Cardiac plexus
■ Pulmonary plexus
■ Celiac plexus
■ Superior mesenteric plexus
■ Esophageal plexus
● The fibers exit from the plexus and heads toward their organ of innervation
○ Synapse on the postganglionic close to to the wall of the organ
■ intramural ganglia
● The postganglionic fibers innervate the visceral organs of thorax and abdomen
○ Reduction of heart rate
○ Constriction of the bronchi of lung (don’t need to breathe deeply)
○ Stimulation of the digestive glands and smooth muscles
Sacral Outflow
● Preganglionic neuron emerge from and are associated with the spinal cord segments of
S2-S4
○ Travel as the pelvic splanchnic to the intramural ganglia/plexus where it
synapses on the postganglionic neuron
● The postganglionic innervates the pelvis, distal large intestine, bladder, and reproductive
organ
○ Allows for the stimulation of defecation, urination and erection
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Clinically apply knowledge of autonomic nervous system. Innervates the smooth and cardiac muscle, glands, and visceral organs (involuntary for the most parts) Overall speed of conduction is slower than the somatic ns. Dorsal and ventral rootlets join into the spinal nerve then split into the dorsal and ventral neuron rami (mixed nerves) Want to converse energy during rest, gear energy towards essential functions like digestion, urination, and defecation. Heart rate and respiratory rate are low. Have long preganglionic fibers and short postganglionic neurons (close to the organ) Cranial outflow part 1: innervation of the head. Preganglionic fibers start from the brainstem runs with the cranial nerve. Will synapse with the postganglionic on the head/neck region. Lacrimal and nasal gland for mucus secretion. Submandibular and sublingual glands for salivation secretion. Cranial outflow part 2: innervation of the organs/trunk. Preganglionic fiber starts from the brainstem and runs with the vagus nerve.
