HOW THE NERVOUS SYSTEM WORKSChapter 6 Section 1Pages 176 - 180

Objective: Describe the role of the nervous system

Functions of the Nervous System:

*Receives information about what is happening insideand 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 thatcan 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 iinternalor external environment & converts each stimulus into an impulse.

*Interneuron: Carries nerve impulses from one neuronto 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 NervousSystem.

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.