Unit_4_Lecture_3 - mail.med.upenn.edu/ Kinesiology 1223...

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Kinesiology 1223 Today’s Lecture Regeneration, Propagation and Transmission of Information, Membrane Potential, Local and Graded Potentials, Action Potentials, Impulse Propagation, Saltatory Conduction, Speed of Conduction, The Synapse, Neurotransmitters, Impulse Transmission, Functional Types of Synapses (p. 462-475) Be Prepared ! Read Topics Before Lecture! Next Lecture: Action Potentials, Impulse Propagation, Saltatory Conduction, Conduction Speed, The Synapse, Neurotransmitters, Impulse Transmission (p. 453-475)
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Quiet Please Turn off cell phones, PDA’s and beepers
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Regeneration of Nerve Tissue Mature neurons cannot regenerate Severe damage or damage close to cell body Entire neuron may die May kill neurons with connections to injured neuron Lack of stimulation
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Nerve Regeneration continued See Saladin Fig. 12.9, p. 452-453 Injured peripheral axons may regenerate 1) Proximal axon end seals off 2) Proximal axon swells up 3) Distal axon begins to degenerate - within minutes - Called Wallerian degeneration
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Regeneration of Nerve Tissue continued Wallerian degeneration Schwann cells & macrophages – phagocytize degenerating axon Axonal sprouts begin to grow Schwann cells align within endoneurium Form a regeneration tube to guide regenerating axonal sprouts to original contacts
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Regeneration of Nerve Tissue continued If reconnected – axon regains function Greater distance between ends – less chance of success Other tissues block path to Schwann cells In CNS: regeneration almost never successful Oligodendrocytes surrounding fibers die No channels formed Glial scar tissue forms and blocks path
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Propagation and Transmission of Information Path of information from receptor to effector Receptor – modified dendritic end organ 1) Sent from receptor across afferent neuron 2) To synapse with association neuron 3) To another association neuron or to efferent neuron 4) Across efferent neuron to effector 5) Effector – muscle, gland
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Basic Information and Review Neurons highly irritable –respond to stimulation When stimulated – electrical impulse along axon Impulse always same – regardless of source or type of stimulus (light, pain, temperature, etc.)
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Resting Membrane Potential: -70mv More K+ inside More Na+ outside Movement through channels in response to electrical and chemical gradients Plasma membrane more permeable to K+
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Resting State cont. Resting membrane potential maintained by: Plasma membrane more permeable to K + than Na + Sodium-potassium pump Must maintain potential difference across membrane To generate nerve impulse which enables neuron to send information to next neuron
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Depolarization of Membrane Depolarization – reduction in membrane potential Inside becomes less negative ( - 70 mv to - 40 mv to - 20 mv) + ions move to cause depolarization
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This note was uploaded on 11/16/2010 for the course KINESIOLOG 1223 taught by Professor Rooney during the Spring '09 term at Temple.

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Unit_4_Lecture_3 - mail.med.upenn.edu/ Kinesiology 1223...

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