| A | B |
|---|
| Adrenals | Endocrine gland on top of the kidney that produces the hormone adrenaline |
| Axon | Tail-like fiber that carries messages away from the cell body |
| Brain | Main control center of the nervous system |
| Cell Body | Largest part of a neuron which contains the nucleus |
| Cerebellum | Part of the brain that controls balance and coordinates muscle activity |
| Cerebrum | Largest part of the brain that controls the senses, thought, and conscious activity |
| Cochlea | Snail shaped tube in the inner ear from which nerve impulses are carried to the brain |
| Cornea | Transparent protective covering of the eye |
| Dendrite | Thread-like structure in a neuron that carries messages to the cell body |
| Hormone | Chemical messenger made by an endocrine gland |
| Interneuron | Type of neuron that connects sensory and motor neurons; found in the brain and spinal cord |
| Lens | Part of the eye that focuses light rays entering the eye |
| Medulla | Part of the brain that controls involuntary movements |
| Motor Neuron | Type of neuron that carries messages from the brain and spinal cord to a muscle cell |
| Negative-Feedback Mechanism | Mechanism by which the production of one hormone is controlled by the amount of another hormone in the blood |
| Neuron | A nerve cell |
| Retina | Inner layer of the eye onto which an image is focused; contains light sensitive rods and cones |
| Semi-Circular Canals | Tiny canal in the inner ear that is responsible for the sense of balance |
| Sensory Neuron | Type of neuron that carries messages from the receptors in any of the five senses to the brain |
| Synapse | Tiny gap between two neurons |
| Hypothalamus | Endocrine gland at the base of the brain that provides a link between the nervous and endocrine systems;controls the other endocrine glands |
| Pituitary Gland | Endocrine gland located below the hypothalamus that controls blood pressure, growth, and metabolism |
| Parathyroid Gland | Endocrine gland embedded in the thyroid that makes a hormone that controls the level of calcium in the blood |
| Reflex | An extremely fast and automatic response to a stimulus, which skips the interneurons in the brain momentarily |
| Stimulus | A change in the environment |
| Pancreas | Endocrine gland that controls the amount of sugar in the blood |
| Testes | Endocrine glands that produce male hormones; male sex gland |
| Ovaries | Endocrine glands that produce female hormones; female sex gland |
| Receptor Cell | A cell that receives information from its surroundings |
| Effector Cell | A muscle cell that is stimulated by a motor neuron |
| Iris | Circular, colored portion of the eye |
| Pupil | Small opening in the middle of the eye |
