BIO 365R lecture 9 - 1 Transmitter is contained in synaptic...

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Unformatted text preview: 1 Transmitter is contained in synaptic vesicles. Fusion of vesicle membrane with membrane of presynaptic neuron causes release of transmitter into synaptic cleft. Transmitter then binds onto receptors on the postsynaptic membrane, and opens the receptors. The opened receptors allow ions to ow into post-synaptic cell, thereby changing the membrane potential. Ions are shown as red balls 2 Inux of Ca++ is key event leading to transmitter release 3 Basal lamina The neuromuscular junction is the synapse made between a motor neuron and a muscle ber and is a very large synapse. The synaptic region on the muscle ber has a special name, the END-PLATE Bernard Katz (1911-2003) Nobel 1970 4 nerve Axon that innervates muscle ber end plate Muscle ber 5 From Dr. Wesley Thompson 6 Stimulation of the nerve always excites skeletal muscle bers. It generates a synaptic potential that is so large, that it always exceeds threshold and generates an AP in the muscle ber The synaptic potential at the neuromuscular junction is called an end-plate potential (EPP). 7 What causes release of transmitter from vesicles? The answer is the inux of Ca++ at the axon terminal through voltage gated Ca++ channels. The Ca++ channels are opened by the depolarization that occurs when an action potential invades the terminal. 8 E Ca ++ = Z 58 log __ [Ca ++ ] i [Ca ++ ] o E Ca ++ = 2 58 log __ [.0000001M ] i [.001M ] o E Ca ++ = 29 log [.0001] i [1.0] o E Ca ++ 29 log [10,000] = E Ca ++ = 29 x 4 E Ca ++ +116 mV = Equilibrium Potential for Calcium 9 epp give pulse of Ca ++ thru pipette resting membrane potential is -70 mv...
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This note was uploaded on 04/12/2009 for the course BIO 51340 taught by Professor Zakon during the Spring '09 term at University of Texas at Austin.

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BIO 365R lecture 9 - 1 Transmitter is contained in synaptic...

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