| A | B |
|---|
| neuron | Functional unit of the nervous system; the cell that receives and distributes nerve impulses. |
| dendrite | Part of the neuron that receives nerve impulses and transmits them toward the cell body. |
| cell body | Part of neuron with the greatest diameter; contains nucleus |
| axon | Portion of a neuron that carries impulses away from the cell body. |
| interneuron | neuron located in the central nervous system; transmits an impulse from a sensory neuron to another neuron. |
| motor neuron | A neuron that receives impulses from the central nervous system and stimulates muscles or glands. |
| nerve impulse | An electrochemical pulse that moves along the membrane of a neuron. |
| synapse | Space between an axon and a dendrite or between the end of an axon and the body structure it affects. |
| reflex arc | Series of neurons which produces a single reaction in response to a stimulus. |
| glial cell | A type of cell dispersed throughout the nervous system which performs beneficial functions for neurons. |
| myelin sheath | White, fatty membrane that protects neurons. |
| cranial nerves | Nerves originating from the brain |
| spinal nerves | Mixed nerves attached to the spinal cord. |
| autonomic nervous system | Involuntary portion of the peripheral nervous system |
| sympathetic nervous system | System of neurons that helps the body adjust to stressful situations. |
| olfactory receptors | Receptors in brain that receives impulses from smell receptors in the nostrils. |
| external auditory canal | Canal from the outer ear to the eardrum. |
| cornea | Transparent anterior portion of the sclera of the eye |
| retina | Innermost layer of the eyeball; composed of specialized neurons and their fibers. |
| lens | A biconvex,semisolid structure that thickens or thins out in order to focus in image on the retina. |
