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Across 1. the supporting structure of nervous tissue, consisting of a fine web of tissue enclosing neuroglial cells 4. Chemicals within the nervous system that transmit information from or between nerve cells. 6. A glial cell that wraps around the nerve fiber in the peripheral nervous system, and forms the myelin sheaths of peripheral axons. 9. The part of the vertebrate nervous system that regulates involuntary action, as of the intestines, heart, and glands, and that is divided into the sympathetic nervous system and the parasympathetic nervous system. 10. a cell of the oligodendroglia 12. the membrane lining the cerebral ventricles and the central canal of the spine 14. a nerve cell that is the basic building block of the nervous system. 15. the section of the nervous system responsible for sensation and control of the skeletal muscles 17. the imbalance of electrical charge that exists between the interior of electrically excitable nerve cellsand their surroundings. 18. an organ that produces an effect in response to nerve stimulation 19. a molecule on the surface or within a cell that recognizes and binds with specific molecules, producing a specific effect in the cell 20. one of the threadlike extensions of the cytoplasm of a neuron; dendrites branch into treelike processes and compose most of the receptive surface of a neuron 22. That portion of the nervous system that is outside the brain and spinal cord. 23. small nonneural cells forming part of the supporting structure of the central nervous system. 24. The portion of a nerve cell that contains the nucleus but does not incorporate the dendrites or axon. 25. A momentary change in electrical potential on the surface of a cell, especially of a nerve or muscle cell, that occurs when it is stimulated, resulting in the transmission of an electrical impulse. 26. surrounds the core of a nerve fiber or axon and facilitates the transmission of nerve impulses 27. a gap occurring at regular intervals between segments of myelin sheath along a nerve axon.

Down 2. star-shaped cell found in certain tissues of the nervous system 3. the site of functional apposition between neurons, where an impulse is transmitted from one to another, 5. is the value of the membrane voltage needed to result in the generation of a full-blown action potential. 7. The portion of the vertebrate nervous system consisting of the brain and spinal cord. 8. a nerve that passes impulses from receptors toward or to the central nervous system 11. An efferent organ or body part, such as a blood vessel. 13. that process of a neuron by which impulses travel away from the cell body; at the terminal arborization of the axon, the impulses are transmitted to other nerve cells or to effector organs 16. Vox populi A popular term, especially among those of lower socioeconomic strata for anxiety, as in she's got nerves 21. a mass of nerve tissue existing outside the central nervous system.