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Unformatted text preview: "Grog" water intake carbohydrates skeletal muscle exertion generation of action potential in the motor cortex of the brain begins with action potential moves through axon of presynaptic neuron or motor neuron increase in the voltage at that point in the cell from -70mV to -55mV depolarization of the neuron at that point the AP travels as a wave of depolarization in the nodes of Ranvier +30 mV opening of voltage-gated Na+ channels inux of Na+ ions along their electrochemical and concentration gradients at -55mV, causes results in influx generates peaks at membrane potential = +30mV voltage-gated K+ channels opens increases the membrane's permeability to K+ ions large outux of K+ ions repolarization (loss of positive on the inside) results in generates-85mV undershoots to inactivation gate of the voltage-gated Na+ channels closes inhibits further inux of Na+ ions-70mV (resting potential) normal K+ movement (to interior) returns potential to positive charges on the interior downstream inux of positive charge caused by pushes increase in voltage further downstream results in propagation of action potential also termed leads to another iteration synapse of the presynaptic neuron and the postsynaptic neuron or muscle cell eventually reaches voltage-gated Ca++ channels arrival of action potential opens inux of Ca++ (extracellular [Ca++] is high) creates vesicles containing neurotransmitters fuse to the axon membrane that faces the synaptic cleft causes release of neurotransmitter into synaptic cleft (exocytosis) causes acetylcholine glycine inhibitory neurotransmitter excitatory neurotransmitter glycine receptor binds to glycine-gated Cl- channel opens inhibitory postsynaptic potential (IPSP) a small hyperpolarization of the postsynatic membrane (reduction in potential = more negative) generates a defined lower motor neurons and at neuromuscular junctions nicotinic acetylcholine receptor lower motor neurons binds to located in the acetylcholine-gated cation (Na+ and K+) channel located on activation opens regeneration of action potential in the post-synaptic neuron or muscle cell excitatory postsynaptic potential (EPSP) opening generates a subthreshold depolarization of the postsynaptic membrane defined sum in multiplicity or high frequency (superposition?) superposition overcomes potential generated by arrives at neuromuscular junction (neuron connected to muscle ber) voltage increase (depolarization) inside of the cell via T tubules voltage-gated Ca++ channels between the sarcoplasmic reticulum and sarcoplasm release of Ca++ ions into sarcoplasm opens propagates causes Ca++ binding to tropomin on the actin lament leads to exposes binding sites for forming a cross bridge with myosin which myosin head absorbs ATP ATP is hydrolized to ADP + Pi release of Pi pivots myosin head and moves the lament subsequently subsequently subsequently sarcomere contraction leads to the overall effect of Ca++ ATPase reclaims calcium ions into the sarcoplasmic...
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This note was uploaded on 06/30/2008 for the course BIOL 220 taught by Professor Weigel during the Spring '08 term at University of Washington.
- Spring '08