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Across 2. The difference in electrical charge between the inside and the outside of an undistributed nerve cell membrane. 7. Stimulation level that must be exceeded to slicit a nerve impulse or a muscle contration. 9. A type of neurologlial cell that connects to blood vessels. 16. A bundle of axons in the peripheral nervous system. 18. Chemicals that axons secrete on effectors or other neurons. 19. The brain and spinal cord. 23. Neuroglial cells that line the ventricles of the brain. 24. A type of neurological cell that surrounds an axon of a perpheral neuron, forming the neurilemmal sheath and myelin. 26. Electrically nuetral subatomic particles.

Down 1. Part of the nervous system outside the central nervous system. 3. Specialized structures associated with the peripheral ends of sensory neurons specific to detecting a particular sensation and triggering nerve impulses in response, which are transmitted to the central nervous system. 4. Motor pathways of the peripheral nervous system that lead to the skin and skeletal muscles. 5. the functional connection between the axons of a neuron and the dentrite or cell body of another neuron or the membrane of another cell type. 6. Process of a neuron that receives input from other neurons. 8. Specialized cells of the nervous system that produce myelin, communicate between cells, maintain the ionic enviroment, and nurture the differentiation of neurons. 9. Part of the nervous sytem that controls the viscera. 10. Vessels that conveys blood to the glomerulus of each kidney nephron in a kidney. 11. The sequence of electical changes that occurs in a pertion of a nerve cell membrane that is exposed to a stimulus that exceeds the membrane's threshold. 12. The gaps (approximately 1 micrometer wide) formed between myelin sheath cells long the axons are called Nodes of Ranvier. 13. Fatty material that forms a sheathlike covering around some axons. 14. The vessels that conducts blood away form the glomerulus of each kidney nephron. 15. A type of neuroglial cell that forms myelin. 17. Portion of nerve that includes a cutoplasmic mass and a nucleus, and from which nerve finers extend. 20. Muscles or glands tha effect changes in the body. 21. A neurolglial cell that supports neurons and phagocytizes. 22. Masses of neuron cell bodies, ususally ouside the central nervous system. 25. A nerve fiber. It conducts a nerve impulse away form the neuron cell body.