THE NERVOUS SYSTEM
Essential Questions
The Nervous System
• What does the
nervous system do?
• How do the parts
of the nervous
system work
together?
Functions of the Nervous System
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The part of an organism that gathers, processes,
and responds to information is called the
nervous system.
The nervous system receives information from the
five senses: vision, hearing, smell, taste, and touch.
The nervous system can receive information,
process it, and respond in less than one second.
Neurons
The basic functioning units of the nervous
system are called nerve cells,
or neurons.
 Neurons help different parts of your body
communicate with each other.
 Neurons are made of three parts: dendrites,
a cell body, and an axon.
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Parts of a Neuron
Parts of a Neuron and their functions
A dendrite receives information from another
nerve cell or body cell.
 A cell body processes the information.
 An axon sends the information to another cell.
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3 types of Neurons
Sensory neurons send information about
your environment to your brain or spinal
cord.
 Motor neurons send information from your
brain or spinal cord to tissues and organs in
your body.
 Interneurons connect sensory and motor
neurons.
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3 types of Neurons
Synapse
The connection between two neurons is
called a synapse.
 Chemical signals carry information
between
neurons.
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Neurons and Synapses
Neurons and Synapses
The Central Nervous System
The central nervous system (CNS) is made up
of the brain and the spinal cord.
 The CNS receives, processes, stores, and
transfers information.
 The brain is the control center of the body
which receives information, processes it, and
sends out a response.
 The brain also stores some information as
memories.
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The Central Nervous System (cont.)
The part of the brain that controls memory,
language, and thought is the cerebrum.
 The cerebrum is the largest, most complex
part of the brain. It processes touch and
visual information.
 The cerebellum is the part of the brain that
coordinates voluntary muscle movement,
balance, and posture.
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The area of the brain that controls involuntary
functions, sneezing, coughing, and swallowing is
the brain stem.
The Central Nervous System (cont.)
The spinal cord is a tube-like structure of
neurons that extend to other areas of the
body.
 Neurons in the spinal cord send information
back and forth between the brain and
other body parts.
 Bones called vertebrae protect the spinal
cord.
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Doug Pensinger/Getty Images
The Peripheral Nervous System
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The peripheral nervous system (PNS), is
made of sensory and motor neurons that
transmit information between the CNS and the
rest of the body.
The PNS is made of two parts: the somatic
system and the autonomic system.
The somatic system controls skeletal muscles.
The Peripheral Nervous System (cont.)
Neurons of the somatic system
communicate between the CNS and
skeletal muscle to cause voluntary
movements.
 The autonomic system controls smooth
(visceral) muscle and cardiac muscle
and regulates involuntary actions.
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