1. The Nervous System

2. Two Main Parts The Central Nervous System
Consists of the Brain and Spinal Cord
The Peripheral Nervous System
Nerve cells that send messages between the central nervous system and the rest of the body

3. Neurons Nerve cells, called neurons, run through our entire bodies.
Neurons send and receive messages
Each of us has over 100 billion neurons
Most of our neurons are found in the brain

4. Components of a Neuron Think of Neurons like trees
Including Branches, Trunk, and Roots
Neurons can lay alongside each other like two trees in a forest
Unlike trees neurons can lay end to end as well, i.e. the “roots” are intertwined with the branches.

5. Components of a Neuron

6. Components again….
Cell Body: Produces energy that fuels the activity of the cell.
Dendrites: “The Branches” receives information from other neurons and passes the message through the cell body.

7. Components are FUN!!
Axon: “Trunk” carries information away from the cell body.
Myelin: A fatty white substance that insulates the axon and speeds the communication.
Axon Terminal: “Roots” End of the axon; send messages to another neurons dendrites.

8. How they Communicate

9. How they Communicate
Synapse: Junction between the axon terminals of one neuron and the dendrites of another.
Messages can only travel in one direction.

10. Neurotransmitters
Neurotransmitters: Chemical stored in sacs within the axon terminal.
Neurons communicate by sending different neurotransmitters between cells.

11. Spinal Cord Column of nerves about as thick as a thumb.
Spinal Reflexes: automatic response Exp: touching a hot stove.

12. Somatic Nervous System
Transmits sensory messages to the central nervous system.
Activated by touch
Exp: Change in temperature, but also includes changes in body position i.e. posture and balance

13. Autonomic Nervous System
Regulates the bodies vital functions
Includes things like heartbeat, breathing, digestion, and blood pressure.
There are two divisions of Autonomic functions.

14. Sympathetic System Known as the “Fight or Flight” response.
Prepares the body to either confront a situation or run away.
Exp: Attacked by a mugger

15. Parasympathetic Nervous System
Normalizes the body after a stressful event.
Brings down heart rate, blood pressure, and breathing.
Sympathetic=Stress Parasympathetic=Peace