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Across 1. narrow gaps between Schwann cells 5. specialized structures associated with 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 7. a type of neuroglia cell that connects neurons to blood vessels 9. muscles or glands that effect changes in the body 12. a bundle of axons in the peripheral nervous system 15. masses of neuron cell bodies, usually outside the central nervous system 17. the brain and spinal cord 18. part of the nervous system outside of the central nervous system 22. the sequence of electrical changes that occurs in a portion of nerve cell membrane that is exposeed to a stimulus that exceeds the membrane's threshold 24. chemicals that axons secrete on effectors or other neurons 25. a neurological cell that supports neurons and phagocytizes 26. carry nerve impulses away from the central nervous system to effectors 27. a type of neuroglial cell that forms myelin

Down 2. part of the nervous system that controls the viscera 3. the functional connection between the axon of a neuron and the dendrite or cell ody of another neuron or the membrane of another cell type 4. the difference in electrical charge between the inside and the outside of an undisturbed cell membrane 6. stimulation level that must be exceeded to elicit a nerve impulse or muscle contraction 8. fatty material that forms a sheathlike covering around some axons 10. neurological cells that line with ventricles of the brain 11. process of a neuron that recieves input from other neurons 13. carry nerve impulses from receptors or sense organs towards the central nervous system. 14. motor pathways of the peripheral nervous system that lead to the skin and skeletal muscles 16. portion of nerve cell that includes a cytoplasmic mass and a nucleus, and from which nerve fibers extend 19. a type of neuroglia cell that surrounds an axon of a peripheral neuron, forming the neurilemmal sheath and myelin 20. a nerve fiber that conducts a nerve impulse away from the neuron body cell 21. nerve cells 23. specialized cells of the nervous system that produce myelin, communicate between cells, maintain the ionic environment, and nurtur the differentiation of neurons