The nervous system has several functions including sending sensory information to the brain, sending commands from the brain to the body, and enabling movement, balance, coordination, reflexes, instincts, thinking, reasoning, memory, emotions, and dreams. It has two main parts - the central nervous system comprising the brain and spinal cord, and the peripheral nervous system comprising nerves in the rest of the body. Neurons are the basic unit of the nervous system, having a cell body, dendrites that receive signals, and an axon that transmits signals. They transmit impulses through electrical signals and neurotransmitters.

1. Nervous System

2. Which organ in your body uses the
most energy?
What is the biggest cell in your body,
and how big is it?

3. Meet Your Brain
• You have about 1 BILLION brain cells
• Your brain is about 2% of your body’s weight, but it
uses about 20% of your energy.
• Left half of brain controls right side of body, and
vice versa
• Longest cell in the body = neuron (nerve cell) that
goes from spine to foot; about 3 feet long

4. What are the functions (job) of the nervous system?
1. Sending sensory information (touch, sight, smell,
taste and sound) from the body to the brain
2. Sending commands from the brain to the body
3. Movement
4. Balance and Coordination
5. Reflexes and Instincts
6. Thinking and reasoning
7. Memory
8. Emotions
9. Dreams

5. What are the 2 parts of the nervous system?
1. Central Nervous System
(CNS) = the brain and the
spinal cord
2. Peripheral Nervous System
(PNS) = all the nerves in
the rest of your body

6. Processing Piece:
Label each of the following as central nervous system
or peripheral nervous system:
1. A group of neurons (nerve cells) in the brain that store
a memory
2. A neuron (nerve cell) that feels pain when your burn
your finger
3. A group of brain cells that control body temperature
4. A neuron in your leg that makes a leg muscle move
when you run

7. What is a neuron?
• A nerve cell
• Has 3 main parts: dendrites, cell body, and axon.

8. What is the function of axons and dendrites?
• Dendrites receive (take in) signals from other
neurons, or from sensory cells (cells that give
information about sight, sound, smell, taste, touch).
• Axons transmit (send) signals to other neurons or to
other cells in the body.

9. Processing Piece:
• Draw a picture of a neuron.
• Label the axons, dendrites, and cell body.
• Show which way a nerve impulse (signal) will travel.

10. What are the 3 types of neurons?
1. Sensory Neurons: receive sensory information
(how something feels, sounds, looks, tastes, or
smells) and sends the information to the central
nervous system (brain and spinal cord)
2. Motor Neurons: carry commands from the central
nervous system (brain and spinal cord) to muscles
and other cells in the body.
3. Interneurons: connect sensory neurons and
motors neurons in the central nervous system

11. Processing Piece:
• Illustrate how information travels from
sensory neurons, to the CNS, then commands
travel back through motor neurons.

12. What is a reflex arc?
1) A sensory neuron sends a signal that part of your body is
in immediate danger:
- Example: Your hand is on a hot stove.
2) The impulse reaches your spinal cord.
3) The spinal cord sends a command through motor neurons
that makes you react quickly.
- Example: You pull your hand away.

13. Processing Piece:
• Write “reflex arc” and draw a picture to
illustrate what this looks like.

14. How do neurons transmit impulses
(send message to other cells)?

15. How do neurons transmit impulses
(send message to other cells)?
1. The dendrites receive a signal from another cell
2. An electrical impulse travels very quickly down the
axon
3. When the electricity reaches the end of the axon,
tiny molecules called neurotransmitters are
released from the end of the axon.
4. The neurotransmitters travel to the dendrites of
the next cell, and trigger a new electrical impulse
in that cell.

16. How neurotransmitters work:

17. What is a neurotransmitter?
• A tiny molecule that carries a message from one
neuron to another.
• Released from the axon of one neuron, into the
dendrite of another neuron.

18. Exit Ticket
1. What are the functions of the nervous system?
2. Draw a neuron. Label the axon, dendrites, and cell
body.
3. Explain how nerves transmit impulses (send
signals) from one cell to the next.
4. What is the central nervous system?