Autonomic Nervous System
Compare the general effects of the sympathetic and parasympathetic divisions of the ANS.
The sympathetic division of the ANS stimulates metabolism, increases alertness, and prepares for emergency in "fight or flight." The parasympathetic division promotes relaxation, nutrient uptake, energy storage, and "rest and repose."
acetylcholine
all preganglionic fibers
Sympathetic preganglionic fibers are characterized as
being short in length and myelinated
The white ramus communicans
carries the preganglionic fibers into a nearby sympathetic chain ganglion
prevertebral
collateral ganglia
preganglionic
first neuron
Splanchnic nerves
include preganglionic fibers that go to collateral ganglia
sympathetic
long postganglionic fiber
Which ganglia belong to the sympathetic division of the ANS?
paravertebral ganglia
splanchnic
preganglionic fibers to collateral ganglia
epinephrine
suprarenal medulla
Cutting the ventral root of the spinal nerve at L2 would interrupt the transmission of what type of information?
voluntary motor output and ANS motor output
In some severe cases, a person suffering from stomach ulcers may need to have surgery to cut the branches of the vagus nerve that innervates the stomach. How would this help the problem?
Cutting off autonomic nervous system stimulation to the stomach through the vagus nerve decreases stimulation of digestive glands, thus reducing their secretion. This may diminish ulcers in the wall of the stomach.
How do sympathetic chain ganglia differ from both collateral ganglia and intramural ganglia?
Sympathetic chain ganglia are innervated by preganglionic fibers from the thoracolumbar regions of the spinal cord, and they are interconnected by preganglionic fibers and axons from each ganglion in the chain innervating a particular body segment. The collateral ganglia are part of the abdominal autonomic plexuses anterior to the vertebral column. Preganglionic sympathetic fibers innervate the collateral ganglia as splanchnic nerves. Intramural gangli are part of the parasymathetic division. They are located near or within the tissues of the visceral organs.
Why are the effects of parasympathetic stimulation more specific and localized than those of the sympathetic division?
The parasympathetic division innervates only visceral structures served by some cranial nerves or lying within the thoracic and/or abdominopelvic cavities. The sympathetic division has widespread impact due to extensive collateral branching of preganglionic fibers, which reach visceral organs and tissues throughout the body.
The effects of epinephrine and norepinephrine released by the suprarenal glands last longer than those of either chemical when released at neuroeffector junctions. Why?
There are no enzymes to break down epinephrine and norepinephrine in the blood and very little enzymes in the peripheral tissues.
The neurotransmitter at all synapses and neuroeffector junctions in the parasympathetic division of the ANS is
acetylcholine
All preganglionic autonomic fibers release _____ at their synaptic terminals, and the effects are always ________.
acetylcholine; excitatory
The large cells in the suprarenal medulla, which resemble neurons in sympathetic ganglia,
release epinephrine and norepinephrine into blood capillaries
Visceral motor neurons in the CNS
send axons to synapse on peripherally located ganglionic neurons
crisis
sympathetic activation
paravertebral
sympathetic chain
thoracolumbar
sympathetic division
What anatomical mechanism is involved in causing a person to blush?
sympathetic stimulation relaxes vessel walls, increasing blood flow to the skin
parasympathetic
terminal ganglia
Preganglionic fibers of the ANS sympathetic division originate in the
thoracolumbar spinal cord
Postganglionic fibers of autonomic neurons are usually
unmyelinated
