April3rd2008 - Neurons Neurons are cells that transmit...

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1 Structure and Function of Nervous System Neurons • Neurons are cells that transmit information • Neurons are composed of: – Cell body : contains nucleus and protein synthesizing machinery for rest of cell – Dendrites : extensions that receive information – Axon : extends from cell body, carries electrical potential, sends a chemical message to adjacent neurons Parts of the Neuron Glial cells • Originally thought to just hold together nerve cells (“glue”), it is becoming clear that glial cells have important effcts on neural transmission Astrocytes and Microglia • Astrocytes – Have distinct “star shape” – Conduit between brain and blood vessels – Can regulate neural transmission • Microglia – Are important component of immune response – Will migrate to sites of brain injury or infection Oligodendrocytes and Schwann Cells • Wrap axons with mylein • In central nervous system: oligodendrocytes • In peripheral nervous system: Schwann cells
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2 Myelination of axons Action Potentials Action potentials , or nerve impulses , are brief but large changes in membrane potential. Patterns of action potentials carry information to postsynaptic targets. Action Potential • APs vary in frequency (a few pulses per second to a max of 1000 pulses per second) • APs have a refractory period (about 1 msec) • AP is “all or none” in nature (AP either occurs or it does not) Chemical basis of action potential Action potentials are produced by the movement of Na + ions into the cell. At the peak the concentration gradient pushing Na + ions in equals the positive charge driving them out. Membrane shifts briefly from a resting state
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This note was uploaded on 09/13/2010 for the course PSC Psychology taught by Professor Cossowings during the Spring '08 term at UC Davis.

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April3rd2008 - Neurons Neurons are cells that transmit...

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