HOW DOES THE
NERVOUS SYSTEM
WORK?
Chapter 12
Section 1
Functions of the nervous system
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

Receives information from inside and outside of the
body
Directs the way the body responds to information
Helps maintain homeostasis


Stimulus: change or signal in the environment
causing a reaction
Response: Reaction to stimulus


Neuron = Nerve cell
Carries nerve impulses/information through the
body
Parts of Neuron


Axon: carries impulses away from the cell body
Dendrites: carry impulses toward the neuron’s cell
body
Three kinds of neurons

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Sensory Neuron: picks up stimuli from the internal or
external environment (also turns stimulus N2 nerve
impulse
Interneuron: carries nerve impulses from one neuron
to another
Motor Neuron: sends impulse to muscle or gland—
then muscle or gland reacts

Synapse: junction where one neuron can transfer an
impulse to another structure

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Nerve impulses must cross the gaps between the
axon and next structure in order for the impulse to
be carried.
Axon tips release chemicals that carry the impulses
across the gap.