nervous system

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Department
Biology
Course
BIOLOGY 152
Professor
Peter Normark
Semester
Spring

Description
The Nervous System 02/06/13 The nervous system has to deal effectively with information in 'real time' how does it do this? Break the problem down: 1. body detects stimulus (light, sound, touch, chemical, temperature, etc.) 2. sensory neuron translates this to something a cell would understand (a chemical/electrical signal) 3. sends signal to Central Nervous System (CNS) 4. interneurons are used to filter, magnify, interpret, or ignore signal 5. CNS directs this modified signal through motor neurons to muscle cells, to endocrine cells (to make hormones), etc. Signal is one way. At axon terminus, it jumps to next cell How does it work? Axon membrane at rest has a negative membrane potential (-70) FACT: diff. [ion] either side; more anions (-) inside Voltmeter used to measure difference in charge between inside/outside of cell to determine membrane potential dif. is maintained by Na+/K pump – for every three Na+ that leave cell, 5 K enter cell Fact: Membrane resting potential = -70 mV Neuron membrane setup: + -voltage-gated Na channel with 2 gates --voltage-gated K channel Fact: Na gate opens when membrane potential > -50 mV Def: graded potential anywhere below -50 mV (& not at resting potential) Fact: K gate opens when memb. pot. > +30 to +40 mV (approx.) =action potential membrane repolarizes when K gates open Starts when (enough) Na gates
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