Download Autonomic Nervous System 9

AUTONOMIC
NERVOUS SYSTEM
PHYSIOLOGY
Fig. 9.1
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Divisions of the ANS
Sympathetic
Parasympathetic
“fight or flight”
“resting and digesting”
mobilizes the body
during extreme situations
performs maintenance
activities and conserves
body energy
Role of the Sympathetic Division
• Involves E activities – exercise, excitement,
emergency, and embarrassment
• Promotes adjustments during exercise – blood
flow to organs is reduced, flow to muscles is
increased
• Its activity is illustrated by a person who is
threatened
– Heart rate increases, and breathing is rapid and deep
– The skin is cold and sweaty, and the pupils dilate
Role of the Parasympathetic
Division
• Involves the D activities – digestion,
defecation, and diuresis
• Its activity is illustrated in a person who
relaxes after a meal
– Blood pressure, heart rate, and respiratory rates
are low
– Gastrointestinal tract activity is high
– The skin is warm and the pupils are constricted
Fig. 9.6
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Fig. 9.2
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Fig. 9.3
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Fig. 9.4
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Fig. 9.5
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Fig. 9.7
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Fig. 9.8
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Fig. 9.9
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Adrenergic Receptors
• There are two major classes of adrenergic
receptors: alpha and beta. Both operate
through second messengers.
• Two subclasses of alpha receptors:
– 1 - On post-synaptic membrane; increases
cytoplasmic Ca2+; excitatory at smooth muscle
– 2 - On pre-synaptic membrane; involved in
feedback inhibition
Adrenergic Receptors
• Two subclasses of beta receptors:
– 1 - Found in the heart and kidney; involved in
heart rate acceleration, and renin secretion.
– 2 - Found in smooth muscle of arterioles at
skeletal muscle, heart and viscera, plus smooth
muscle of bronchioles; involved in vasodilation
and dilation of bronchioles.
Fig. 9.10
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Table. 9.7
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