Nervous System Deck
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nervous system
the communication network for the body; the most highly organized system
the main function of the nervous system
to coordinate all of the body’s activities
when changes occur inside or outside the body
the nervous system allows it to recognize them and respond as needed
the basic element of the nervous system
the neuron
neuron/nerve cell
job is to transmit a message from one cell to the next
in order for a neuron to perform its job
contains special fibers that extend from the cytoplasm of the cell body
dendrites
conduct impulses toward the cell
a nerve cell
may have several dendrites
axons
conduct impulses away from the cell
each nerve cell
has only one axon
many axons
covered by a fatty tissue called the myelin sheath
myelin sheath
protects the axons and speeds up the impulse as it travels
impulse
refers to a force that produces sudden activity in nerve cells and is transmitted in a wave along nerve fibers
the axon of one neuron
lies close to many dendrites of other neurons
synapse
the space between a dendrite and an axon
neurotransmitters
special chemicals that help impulses “jump” the synapse to pass the message from cell to cell
neurons
form bundles called nerves
the impulses
can follow many different routes throughout the body
types of neurons
afferent, efferent, associative
afferent neurons/sensory neurons
carry messages from all parts of the body to the brain and spinal cord
efferent neurons/motor neurons
carry messages from the brain and spinal cord to the muscles and glands
associative neurons/interneurons
carry messages from afferent neurons to efferent neurons
the two main divisions of the nervous system
central nervous system and peripheral nervous system
central nervous system
consists of the brain, spinal cord, optic (eye) nerves