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visceral (organ) motor system
involuntary control of effectors: glands, cardiac muscle, and smooth muscle
visceral reflexes
unconscious, automatic stereotyped responses of visceral effectors to stimuli
ex: rise in blood pressure triggers a reflexive decrease in heart rate
effector
they cause an effect in response to directions from the nervous system
divisions of the ANS
sympathetic “fight or flight”
parasympathetic “rest and digest”
autonomic tone
balance btwn activity of sympathetic and parasympathetic nervous system
sympathetic division
fight or flight responses for increased physical activity
increases heart rate and blood glucose
reduces blood flow to skin and GI tract
parasympathetic division
rest and digest responses with calming effects
decreases heart rate
stimulates digestion and waste elimination
neural pathways
preganglionic fiber
neurosoma in brainstem or spinal cord
axon terminates in ganglion
postganglionic fiber
neurosoma in ganglion
axon extends to target
preganglionic fiber
neurosoma in brainstem or spinal cord
axon terminates in ganglion
postganglionic fiber
neurosoma in ganglion
axon extends to target
somatic
effectors: skeletal muscle
control: usually voluntary
efferent pathways: one nerve fiber from CNS to effector; no ganglia
effect on target cells: always excitatory
autonomic
effectors: glands, smooth muscle, cardiac muscle
control: usually involuntary
efferent pathways: 2 nerve fibers from CNS to effector; synapse at a ganglion
effect on target cells: excitatory or inhibitory
sympathetic division
thoracolumbar division
preganglionic neurosomas are in lateral horns of spinal cord
short preganglionic fibers and long postganglionic fibers
sympathetic chain ganglia (paravertebral ganglia) from cervical to coccygeal levels
short
preganglionic fibers in the sympathetic division are ____?
long
postganglionic fibers in the sympathetic division are ____?
sympathetic chain ganglia
from cervical to coccygeal levels
parasympathetic division
craniosacral division
long preganglionic fibers and short postganglionic fibers
terminal ganglia are in or near target organ
long
preganglionic fibers in the parasympathetic division are _____?
short
postganglionic fibers in the parasympathetic division are _____?
enteric nervous system
nervous system of the digestive tract
innervates smooth muscle and glands
regulates
motility of the esophagus, stomach, and intestines
secretion of digestive enzymes and acid
sympathetic
Origin in CNS: Thoracolumbar
Location of ganglia: Paravertebral ganglia adjacent to spinal column and prevertebral ganglia anterior to it
Fiber lengths: Short preganglionic Long postganglionic
Effects of system: Often widespread and general
parasympathetic
Origin in CNS: Craniosacral
Location of ganglia: Terminal ganglia near or within target organs
Fiber lengths: Long preganglionic Short postganglionic
Effects of system: More local and specific
disorders of the ANS
horner syndrome - unilateral pupillary constriction, sagging of eyelid, and flushing of skin due to lesions in sympathetic division
raynaud disease - paleness, cyanosis, and pain in digits when cold or stressed due to excessive vasoconstriction (most common in young women)
myelinated fiber
preganglionic fiber
unmyelinated fiber
postganglionic fiber
thoracolumbar
where do the nerves of the sympathetic nervous system arise from
brainstem and sacral
where do the nerves of the parasympathetic nervous system arise from
enteric
Regulate motility through digestive tract
Regulate secretion of digestive enzymes