Chapter 15: Autonomic Nervous System & Visceral Sensory Neurons

Front 1

Peripheral Nervous System Divisions

Back 1

PNS---->1. Sensory Division (afferent) [a). somatic sensory & b.) visceral sensory]
---------->2. Motor Division (efferent) [a. somatic nervous system & b.) autonomic nervous system {i. sympathetic division & ii. parasympathetic division}]

Front 2

Peripheral Nervous System: Autonomic Nervous System

Back 2

-Only motor nerves with motor neurons
-Only innervate smooth muscle, cardiac muscle, and glands
-involuntary
-regulates VISCERAL MOTOR FUNCTIONS (heart rate, digestion, blood pressure, urination)
-maintains homeostasis by either increasing or decreasing activity

Front 3

Autonomic System Divisions: Parasympathetic & Sympathetic Divisions

Back 3

-Sympathetic Nervous System---speeds up activity (fight or flight); inenrvates smooth muscle in walls of blood vessels [vasoconstriction], heart pumps blood harder)

-Parasympathetic Nervous System---slows down activity; most active when body is at rest; "rest & digest"

Front 4

Motor Division of Peripheral Nervous System

Back 4

-Somatic nervous system (voluntary)---skeletal muscles; *single* neuron innervating muscle
-Autonomic nervous system (involuntary)---smooth muscle, cardiac muscle, glandular epithelium; *two* neurons innervating muscle

Front 5

Details on Somatic (voluntary) Nervous System

Back 5

-single axon (ONE neuron innervating muscle)
-cell bodies ONLY in CNS
-innervates skeletal muscle
-voluntary
-each somatic motor neuron runs from the CNS, all the way to the muscle being innervated
-each somatic motor neuron consists of a single neuron
plus the skeletal muscle cells that it innervates
-typical somatic motor axons are thick, heavily myelinated fibers that conduct nerve impulses rapidly

Front 6

Details on Autonomic Nervous System

Back 6

-includes pre & post-ganglionic neurons (TWO motor neurons innervating muscle)
-cell bodies found inside AND outside CNS
-involuntary

Front 7

Ganglion

Back 7

in the autonomic nervous system, it is a clump of cell bodies outside the CNS
-autonomic ganglia are MOTOR ganglia containing cell bodies of motor neurons

Front 8

Pre-ganglionic neuron

Back 8

-part of motor unit in ANS
-myelinated
-cell body found within CNS
-smooth muscle
-travels to ganglion, its preganglionic axon then synapses w/ post-ganglionic neuron
-functionally, the preganglionic neuron signals the postganglionic neuron
-includes WHITE RAMUS COMMUNICANS

Front 9

Post-ganglionic neuron

Back 9

-unmyelinated
-part of motor unit in ANS
-larger diameter
-voluntary/somatic motor axon (skeletal muscle)
-slower signal transmission
-ravels to effector visceral organs: cardiac muscle, smooth muscle, glandular epithelium, adipose tissue
-includes GRAY RAMUS COMMUNICANS

Front 10

Sympathetic vs. Parasympathetic

Back 10

-these two divisions of the ANS arise from different regions of the CNS
-the PREGANGLIONIC axon terminals of both divisions BOTH RELEASE ACETYLCHOLINE

-Sympathetic division is aka the THORACOLUMBAR division bc its fibers emerge from the thoracic & superior lumbar parts of the spinal cord
-----sympathetic pathways have SHORT PRE-ganglionic neurons & LONG POST-ganglionic neurons; sympathetic fibers branch profusely
-------SYMPATHETIC POSTGANGLIONIC NEURONS RELEASE NOREPINEPHRINE (NOADRENALINE); adregenic effects


-Parasympathetic division is aka the CRANIOSACRAL division bc its fibers emerge from the brain and the sacral spinal cord
-----parasympathetic have LONG PRE-ganglionic neurons & SHORT POST-ganglionic neurons
-PARASYMPATHETIC POSTGANGLIONIC NEURONS RELEASE ACETYLCHOLINE

Front 11

Sympathetic:
THORACOLUMBAR
Trunk Ganglia (aka paravertebral ganglia)

Back 11

-pre-ganglionic neurons exit spinal cord through ventral root from T1-L2, go into spinal nerve to reach ganglia (VIA WHITE RAMI); then axon for 2nd postganglionic neuron leaves via GRAY rami
-paravertebral ganglia joined to ventral rami of nearby spinal nerves by white & gray rami communicantes
-preganglionic is WHITE rami
-post ganglionic is GRAY rami

Front 12

Parasympathetic:
CRANIOSACRAL

Back 12

-4 cranial nerves (III, VII, IX, X)
-sacral spinal nerves (S2-S4)
-cranial outflow of parasympathetic division originates from sacral spinal cord and supplies the rest of the abdominal organs and the pelvic organs

Front 13

BIG PICTURE OF THORACOLUMBAR VS CRANIOSACRAL

Back 13

-Thoracolumbar---SPEEDS UP
-Craniosacral---SLOWS DOWN
-BOTH INNERVATE THE SAME STRUCTURES

Front 14

Terminal Ganglia

Back 14

NOT located next to spinal cord, they're found ON or NEAR the effector organ

Front 15

PARASYMPATHETIC LENGTH OF FIBERS

Back 15

-LONG PRE-GANGLIONIC
-SHORT POST-GANGLIONIC

Front 16

SYMPATHETIC LENGTH OF FIBERS

Back 16

-SHORT PRE-GANGLIONIC
-LONG POST-GANGLIONIC

Front 17

Effects of autonomic stimulation

Back 17

-The eye:
---sympathetic: pupils dilate, increase activity
---parasympathetic: pupils constrict
-Glands:
---sympathetic: increase sweat, decrease saliva
---parasympathetic: increase tears, inecrease saliva
-Heart:
---sympathetic: increase HR
---parasympathetic: decrease HR
-Blood vessels:
---sympathetic: vasoconstriction, increase BP
---parasympathetic: vasodilation? (muscle in blood vessels can only make them smaller, no real effect on venous side)
-Lungs:
---sympathetic: dilation of bronchioles
---parasympathetic: constriction of bronchioles (don't need all lung capacity)
-GI tract:
----sympathetic: sphincters closed (humans different animals)
---parasympathetic: sphincter closing inhibited