HOW THE NERVOUS
SYSTEM WORKS
Chapter 6 Section 1
Pages 176 - 180
Objective: Describe the role of the nervous system
Functions of the Nervous System:
*Receives information about what is happening inside
and outside your body.
*Directs the way in which your body responds to this
information.
*Your Nervous System helps maintain homeostasis
Stimulus: any change or signal in the environment that
can make an organism react.
Response: Is what your body does in reaction to a
stimulus.
Neurons: Cells that carry information through your
Nervous System.
Nerve – Impulse: The message that a neuron carries.
(Usually an electric or chemical signal.)
Dendrite: Carries impulses toward the cell body. It is a
thread-like extension of the neuron.
Axon: Carries impulses away from the cell body. There
is only ONE axon per neuron.
Nerve: A bundle of nerve fibers.
3 Types of Neurons are found in the body…
*Sensory Neurons: Picks up stimuli from the iinternal
or external environment & converts each stimulus
into an impulse.
*Interneuron: Carries nerve impulses from one neuron
to another. Ex. Can pass sensory impulses to motor
neurons.
*Motor Neuron: Sends impulses to a muscle and the
muscle contracts in response.
Together these 3 types of neurons make up a chain of
nerve cells that carry an impulse through the Nervous
System.
How a Nerve Impulse travels…
*Begins in the Dendrite
*Moves rapidly toward the cell body
*Then down the axon to the tip
Synapse: A tiny space between each axon tip and the
next structure.
An impulse crosses the gap with the help of chemicals
from the axon tip that help the impulse get across the
gap.