Across
- 6. support cells are grouped together.
- 10. electrochemical change in a neuron to send a signal.
- 13. involuntary and controls smooth and cardiac muscles and glands.
- 14. bundles of nerve fibers in the PNS.
- 20. fibers that extend from the cell body.
- 22. cells line cavities of the brain and spinal cord.
- 25. brain and spinal cord.
- 26. clusters of cell bodies in the CNS.
- 29. membrane permeability changes again, becoming impermeable to sodium ions and permeable to potassium ions, which rapidly diffuse out of the neuron.
- 30. spiderlike phagocytes that monitor health of nearby neurons and dispose of debris.
- 32. cells form myelin sheath around nerve fibers.
- 34. cells protect and cushion neuron cell bodies.
- 35. bundles of nerve fibers in the CNS.
- 38. functional junction between nerves where a nerve impulse is transmitted.
- 40. division of nerve fibers that carry impulses away from the central nervous system organs to effector organs.
- 41. ability to transmit the impulse to other neurons, muscles, or glands.
Down
- 1. nerves carry impulses to and from the spinal cord.
- 2. stress response
- 3. activates muscles or glands.
- 4. nerves carry impulses to and from the brain.
- 5. plasma membrane that is inactive.
- 7. ability to respond to a stimulus and convert it to a nerve impulse.
- 8. collections of cell bodies outside the CNS in the PNS.
- 9. restores initial conditions of sodium and potassium ions using ATP.
- 11. are nerve cells that are specialized to transmit impulses.
- 12. nervous system processes and interprets sensory input and decides whether action is needed.
- 15. voluntary and controls skeletal muscles.
- 16. wrap around nerve fibers in the central nervous system and produce myelin sheaths.
- 17. relaxation response
- 18. division of nerve fibers that carry information to the central nervous system.
- 19. white, fatty material covering axons; protects and insulates fibers and speeds nerve impulse transmission.
- 21. cleft gap between axon terminals and the next neuron.
- 23. nerves extending from the brain and spinal cord.
- 24. conduct impulses away from the cell body; only one per neuron.
- 27. gathering information
- 28. matter is collections of myelinated fibers (tracts).
- 31. matter mostly unmyelinated fibers and cell bodies.
- 33. are abundant, star-shaped cells that brace and anchor neurons to blood capillaries.
- 36. sodium channels open, and sodium (Na+) diffuses into the neuron.
- 37. body nucleus and metabolic center of the cell.
- 39. conduct impulses toward the cell body; may be hundreds per neuron.