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V. Nervous System
A. Purpose: controls the body’s reaction to the
outside world.
1. Controls actions, emotions, thoughts,
memories, sensations, and senses.
B. Collects information from inside and outside
the body
1. Responds to stimuli (events or conditions
that cause a living thing to react)
2. Neurons (nerve cells) carry messages
throughout the body
a. Main part: cell body
b. dendrites: short strands coming off
the cell body that bring in messages
c. axon: single long strand on the other
end of the cell body; carries
messages away from the cell body
d. impulse: the message that travels
through the neuron
e. synapse: the gap between two
neurons
3. Three types of neurons
a. sensory neuron: carries impulses to
the brain
b. motor neuron: carry impulses from
the brain
c. association neuron: impulses from
the brain to other organs
4. The main control center: the brain
5. Spinal chord: sends messages throughout
the body and the brain