1. The Nervous System (Ch.18)
Unit 7:
The Nervous System (Ch.18)

2. Functions Stimulus- something that causes a reaction.
the nervous system gathers, processes, and responds to information
Receives information about what is happening both inside and outside your body.
Directs the way in which your body responds to information.
Stimulus- something that causes a reaction.
Response- what you do in reaction to a stimulus.
Helps maintain homeostasis. Protects from harm and directs signals to eat, sleep, etc.

3. The Neuron Neuron- nervous system cell.
Nerve impulse- the signal that neurons carry.
Neuron has a large cell body that contains organelles and threadlike extensions called dendrites, and a long axon.

4. - How the Nervous System Works
The Neuron
The structure of a neuron allows it to carry nerve impulses.
Axon- carries impulses away from the neuron.
Dendrite- carries impulses towards the neuron.

5. Rat Neurons at work

6. Human neuron

8. Kinds of Neurons
Sensory Neuron- picks up stimuli from the internal or external environment.
Interneuron- carries impulses from one neuron to another.
Motor Neuron- sends an impulse to a muscle or gland.

9. The Synapse Synapse- the gap between two neurons.
For a nerve impulse to be carried along at a synapse, it must cross the gap between the axon and the next structure.
The axon tips release chemicals that carry the impulse across the gap.

10. How a Nerve Impulse Travels
- How the Nervous System Works
For a nerve impulse to be carried along at a synapse, it must cross the gap between the axon and the next structure. The axon tips release chemicals that carry the impulse across the gap.