The autonomic nervous system

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The autonomic nervous system Involuntary
control somatic motor neurons control
skeletal muscle Autonomic- cardiac and smooth
muscles, glands
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Effector organs Smooth muscles retain resting
tone in absence of stimulation Muscles can
contract in the absence of direct innervation AC
h always stimulates skeletal muscles, but
its effects may vary in autonomic system
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Sympathetic and parasympathetic
systems Sympathetic (thoracolumnar) Parasympathe
tic (craniosacral) also cranial
nerves According to their point of contact with
the spinal cord
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Response depends on type of receptor stimulated
Cholinergic- Ach all preganglionic fibers most
parasympathetic Adrenergic- norepinephrine most
sympathetic Depends on receptors See table 9.6,
p. 229 (9.4, p. 227 in new book!)
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Some organs have dual innervation complementary
effects Some have only sympathetic
innervation adrenal medulla, sweat glands,
blood vessels Regulation by change in level of
stimulation
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Control of autonomic system in brain Medulla
oblongata vagus nerve transmits it (see Table
9.8) Medulla is itself controlled by
hypothalamus hunger and thirst pituitary
gland emotions (limbic system and
cortex) Connection with cerebellum- sense of
balance, motion sickness