| A | B |
|---|
| central nervous system | a collection of organs whose primary function is to process all incoming and outgoing messages from the nerves; includes the brain and the spinal cord |
| peripheral nervous system | the nerves whose primary function is to exchange information from all areas of the body and the outside environment to the central nervous system to the rest of the body |
| neuron | a specialized cell that tranfers messages throughout the body in the form of fast-moving electrical signals |
| impulse | an electrical message that passes along a neuron |
| receptor | a specialized dendrite that detects changes inside or outside the body |
| nerve | an axon bundled together with blood vessels and connective tissue |
| brain | mass of nerve tissue that is the main organ of the nervous system |
| reflex | a quick, involuntary response to a stimulus |
| retina | layer of light-sensative cells in the back of the eye |
| rods | photoreceptors that can detect bright light and that help you see colors |
| cones | photoreceptors that can detect bright light and that help you see colors |
| iris | the colored part of the eye |
| lens | a curved, transparent object that forms an image by refracting light |
| cochlea | an ear organ that converts sounds waves into electrical impulses |
| endocrine system | a collection of organs, called glands, whose primary function is to control body fluid balance, growth, and sexual development |
| gland | a group of cells that make special chemicals for the body |
| hormone | a chemical messenger that carries information from one part of an organism to the other, made by the endocrine system |
| feedback control | the system that turns endocrine glands on or off |
