Final notes Neurons

Final notes Neurons - Neurons Process and act on sensory...

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Unformatted text preview: Neurons Process and act on sensory information Nervous system Rapid transfer of information through the body by electrical signals or nerve impulses Cell body Contains the nucleus and organelles Clusters of cell bodies are ganglia Dendrites Highly branched processes Receive incoming information Carry this information as an electrical signal to the cell body Axon Longer processes Only one per neuron Carry information to other cells Vertebrate axons are insulated with myelin sheaths Myelinated (fast conducting) Non-myelinated (slow conducting) Synaptic terminal Specialized ending of axon Relays message to target cell by releasing neurotransmitters Threshold stimulus Smallest (depolarizing) voltage required to elicit an action potential Action potential Only t riggered in the axon This is the nerve impulse Stereotypical All-or-nothing response Rising phase of the action potential Na channels open K channels closed Refractory period Hyperpolarization of the nerve membrane Interior more negative than the resting state Cannot generate another nerve impulse during this period Graded potentials Hyperpolarization Depolarization Hyperpolarization More negative More negative than the -70 mV resting potential Open potassium channel, potassium flows out, leaving a more negative internal environment Depolarization More positive Open sodium channels, sodium flows in, more positive ions in the axoplasm Action potential Depolarization reaches the threshold potential (-50 to -55 mV) Trigger action potential All-or-nothing response...
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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Final notes Neurons - Neurons Process and act on sensory...

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