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Unformatted text preview: Chapter 17: The Nervous System: Organization External/Internal stimuli receptors (usually a cell, but can be part of neuron) sensory neurons interneurons (calculate appropriate response) motor neurons (mediates response to something) effector response The nervous system receives input from the environment via sensory neurons, calculates a response, and executes that response. The nervous system is the bodys way of having short-term communicating with itself Endocrine system- long term communication Features of neurons Cell body-nucleus found here Axon- long protruding Axon terminal-communicates with other neuron-end of axon-usually chemical signal that travels across the synapse-electrical signal travels down the axon Dendrites-receive signals Action Potential- electrical impulse-movement of ions from the outside of the cell to the inside in the cell and then back-electrical disturbance- strategies to increase speed of action potential: 1. increase the diameter of the axon a. cells wrap around the axon that insulates the axon b. these regions dont conduct electric so the AP jumps from one conductive region to the next Schwann cells , containing the insulating material, myelin , wrap around axons to increase speed of conduction an alternative to larger diameter axons found in many invertebrates-migrate out during development- Nodes of Ranvier : spaces between schwann cells that conduct nerve impulses-Lampreys dont have Schwann cells or Neurons connect to other neurons at the synapse , a space where neurotransmitters mediate signals Neurons come in 2 basic morphologies others exist but rare 1)...
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This note was uploaded on 08/16/2008 for the course BIOL 276 taught by Professor Johnson during the Spring '07 term at UNC.
- Spring '07