Transcript 35-2 The Nervous System

35-2 The Nervous System
Pg. 897
Introduction
• 1. The Nervous
system controls and
manages functions
in response to
internal and external
stimuli.
Introduction
• 2. Homeostasis occurs when organisms keep
internal conditions constant despite changes
in external conditions.
A. Neurons
• 1. Neurons are the cells that send messages
through the body.
A. Neurons
• 2. The largest part of a neuron, containing the
nucleus and most of the cytoplasm, is the cell
body.
A. Neurons
• 3. Short and branched extensions that spread
out from the cell body are called dendrites.
A. Neurons
• 4.The long fiber that carries a nerve impulse
away from the cell body is called an axon.
A. Neurons
• 5. Some axons are insulated by a membrane
called a myelin sheath.
• 6. Axons that have a myelin sheath increase
the speed a nerve impulse can travel.
Please
Draw and
Label this
picture
B. The Nerve Impulse
• 1. The resting potential of a neuron is the
electrical charge of a neuron at rest.
B. The Nerve Impulse
• 2. A neuron at rest, has more positive charges
on the outside of the cell and more negative
charges in the cell.
B. The Nerve Impulse
• 3. When a neuron is stimulated by the
environment or another neuron, an impulse
(signal) travels through that neuron.
B. The Nerve Impulse
• 4. Protein channels along a neuron act as
gateways for negative and positive charges.
B. The Nerve Impulse
• 5. When the charges are
reversed from positive
to negative, the neuron
has an impulse in
progress, or the action
potential.
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C. The Synapse
• 1. The synapse is the space that separates the
axon terminal of one neuron from the
dendrites of the neighboring neuron.
C. The Synapse
• 2. Neurotransmitters are chemicals that travel
along the synapse to transmit the impulse to
the next neuron.
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