174 The Peripheral Nervous System The peripheral nervous system is composed of nerves and ganglia Nerves are bundles of axons Ganglia are collections of cell bodies The peripheral nervous system is subdivided into the somatic system and the autonomic system ID: 781421
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Slide1
17.4 The Peripheral Nervous System
Slide217.4 The Peripheral Nervous System
The peripheral nervous system is composed of nerves and ganglia.
Nerves
are bundles of axons.
Ganglia
are collections of cell bodies.
The peripheral nervous system is subdivided into the somatic system and the autonomic system.
Slide3Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
b.
spinal
nerve
dorsal
root
ventral
root
dorsal root
ganglion
Slide4Somatic
System
Somatic System
The somatic system serves the skin, skeletal muscles, and tendons.
Some actions in the somatic system are due to reflexes, which are automatic responses to a stimulus.Most actions in the somatic system are voluntary
Slide5Somatic System
The Reflex Arc
programmed, built-in circuits that allow for protection and survival.
require no conscious thought
Nerve impulses travel from the sensory neuron to the spinal cord and back to the motor neuron.
Slide6Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
pin
central canal
white matter
gray matter
dorsal
horn
Dorsal
dorsal horn
dorsal root ganglion
sensory
receptor
(in skin)
axon of sensory neuron
cell body of sensory neuron
cell body of interneuron
axon of motor neuron
ventral root
cell body of
motor neuron
ventral horn
Ventral
ventral horn
effector
(muscle)
Slide7Autonomic System
function automatically and usually in an involuntary manner
regulates
the activity of cardiac and smooth muscle and glands.
composed of the sympathetic and parasympathetic divisions. innervate all internal organsutilize two motor neurons that synapse at a ganglion.
Slide8Autonomic System
Sympathetic Division
important during emergency
situations
“fight or flight” response: adrenalin released, increasing heart rate, increased breathing rate, etc.Parasympathetic Divisionsometimes called the housekeeper division because it promotes all the internal responses we associate with “rest and digest.”
Slide9Table 17.1