| A | B |
|---|
| stimulus | a change in environment that causes a person to react |
| central nervous system | the brain and spinal cord together |
| neuron | a nerve cell found in the brain |
| peripheral nervous system | all the nerves not in the central nervous system |
| autonomic nervous system | nerves that control automatic functions |
| voluntary nervous system | nerves that control voluntary movements |
| endocrine system | the system that controls body conditions with chemical messengers |
| hormone | a chemical change that is made in one organ and travels through the blood to another organ |
| gland | the main structure of the endocrine system, some glands release hormones into the circulatory system |
| menstruation | the flow of blood and tissue from a womans body over a period of about 5 days |
