Nervous System
Important Vocabulary
• Neuron
• Dendrite
• Axon
• Sensory neuron
• Interneuron
• motor neuron
• Synapse
• Central nervous system
• Peripheral nervous
system
• Cerebrum
• Cerebellum
• Brain stem
• reflec
EXPLORE ACTIVITY pg. 677
• What did you find out about their
heights? How were your eyes
tricked?
Response to Stimuli
• Any change inside or outside your body that
brings a response is called a stimulus
• Stimuli
•
•
•
• Our bodies have internal control systems that
maintain homeostasis
• Breathing, heartbeat,digestion
Neurons
• Neuron: the working unit of the nervous system
• A neuron is made up of a cell body and branches
called dendrites
• Dendrites receive messages and send them to the
cell body
• An axon carries messages away from the cell body
• Messages carried by a neuron is called an impulse
• https://www.youtube.com/watch?v=cUGuWh2UeM
k&list=PLLEfSFm6js-_SjqVDF3bcG6lox9O43h_L
Types of Neurons
1. Sensory: receive information and send
impulses to the brain or spinal cord
2. Interneurons: relay impulses from the sensory
to motor neurons. There are more of
interneurons than any other type
3. Motor: conduct impulses from the brain or
spinal cord to muscles or glands throughout
your body.
• https://www.youtube.com/watch?v=C4Gt322-XxI
Synapse
• Since neurons don’t touch each other, how does
an impulse move from one another?
• Synapse: small space where an impulse
moves from one neuron to another.
• When impulse reaches the end of the
axon, a nerve transmitting chemical is
released by the axon
• This chemical diffuses across the synapse
and starts an impulse in the dendrite or
cell body of the next neuron
CNS AND PNS
Central Nervous System
• Made up of the
• Brain
• Spinal cord
• All body activities are coordinated
• If steps on your foot, your whole body reacts
The Brain
• Made up of 100 billion neurons
• Divided into 3 parts
• Cerebrum
• Cerebellum
• Stem
• Cerebrum:
• divided into two large sections called
hemispheres
• Impulses from the senses are interpretted,
• Memory is stored
• Voluntary muscle control center
The Brain
• Cerebellum
• Behind and under the cerebrum
• Coordinates voluntary muscle movement
• Maintains balance and muscle tone
• Stem
• Extends from the cerebrum and connects the
brain to the spinal cord
• Parts: midbrain, pons, medulla
• Controls heartbeat, breathing, blood pressure
Peripheral Nervous System
• Brain and spinal cord are connected to the rest
of your body by the peripheral nervous system
• Made up of 12 pairs of cranial nerves from your
brain
• 31 pairs of spinal nerves from your spinal cord
• These nerves link your CNS with all parts of your
body
• Spinal Nerves: made up of bundles of sensory
and motor neurons
• Somatic System and autonomic system
Somatic and Autonomic System
• Somatic: consists of the cranial and spinal nerves
that go from the CNS to your skeletal muscles
• Connect the central nervous system to the organs,
muscles, and skin
• It is like a passageway from the environment to
the central nervous system
• processing sensory information that arrives via
external stimuli including hearing, touch and sight
• Autonomic: controls heartbeat rate, breathing,
digestions and gland functions
• When salivary glands release saliva
Reflex
Drugs and the Nervous System
Activity 25-1 p. 685