10-Nervous System I-1

10-Nervous System I-1 - 1.FunctionoftheNervousSystem...

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Nervous System 1. Function of the Nervous System 2. Nervous Tissue Neurons Glia The Idealized Neuron 3. Signaling in the Nervous System How Ions Cross Membranes Resting Potentials, Graded Potential and Action Potentials 4. Mechanisms Resting Potential Graded Potentials Action Potentials
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Ne rvo us  S ys te m  Func tio n Fig. 48.3 Campbell   The function of the nervous system is to  receive (sensory input), process (integration)  and rapidly transmit information directing the  appropriate physiological or behavioral  response (motor output) with a provision for  modifying the response with experience  (learning).   All of these processes involve changes in the electrical potential difference (voltage) across the plasma membrane that arise from the regulated movement of ions across the membrane.
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Structure of Nervous Tissue: Neurons Approximately 50% of volume of the nervous  tissue is made up of nerve cells (neurons)
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And Neuroglia: CNS:   Astrocytes, Oligodendorcytes  PNS: Schwann Cells The remaining 50% of nervous tissue is largely  made up of glial cells (or neuroglia) which  outnumber neurons 10 to 1. Neuroglia have a  variety of support functions and are responsible for  the formation of  myelin .
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The Idealized Neuron Cell Body Dendrites Axon 1.  Cell body  – nucleus, protein  synthesis 2.  Dendrites  – surface for  receiving information - input 3.  Axon  – rapid transmission and,  at the  Axon Terminal, signalling the next cell - output  cell body
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Neurons : Structure, Organization, Communication = Direction of  information flow
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What Factors Control Ion Movement Across the  Cell Membrane ? Any molecule, atom, or ion will tend to flow from  higher concentration to a lower concentration (Simple  Diffusion)  Like charges repel and opposite charges attract Electrochemical Gradient: Combination of  these two
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How Do Ions Cross the Cell Membrane? The lipid bilayer is generally impermeable to ions.  Therefore the movement  across membranes involves integral membrane proteins. There are two general  types of these proteins: ATP-dependent pumps (movement against  electrochemical gradient) Ion Channels (movement with  electrochemical gradient)
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Gated Ion Channels Kandel, Schwatrz, Jessel Essentials of Neural Science Ligands Phosphorylation Voltage (Vm) Mechanical
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Membrane Potentials An unequal distribution of charge results in an electrical potential difference across  the membrane – (more negatively charged ions inside the cell means the inside is at a 
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This note was uploaded on 11/12/2010 for the course BSCI BSCI 110B taught by Professor Johnson during the Spring '09 term at Vanderbilt.

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10-Nervous System I-1 - 1.FunctionoftheNervousSystem...

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