1. Nervous System
Controls and coordinates your body's activities and helps you sense and respond to changes in your environment.

2. Neuron
A cell of the nervous system or a nerve cell

3. Synapse
The small junction across which a nerve impulse passes from one nerve cell to another nerve cell, muscle cell, or a gland cell.

4. Senses
Any of the 5 faculties, such as sight, hearing, smell, taste, or touch in which humans or animals perceive stimuli coming from the outside or inside the body

5. Brain
Organ that is the control center for actions, thoughts, and emotions

6. Spinal Cord
A bundle of nerves that goes from the brain stem down the center of the backbone

7. Nerves
Bundle of fibers made up of neurons that carry sensory and motor information throughout the body in the form of electrical impulses.

8. External Stimuli
A stimulus that comes from outside the body of an organism and that influences the behavior of the organism. Examples: temperature, sound, light and other organisms.

9. Fight or Flight Response
A biochemical reaction that both humans and animals experience during intense stress or fear. The nervous system releases hormones causing changes to occur throughout the body.