lecture7 sq key - Short Answers to Lecture 7 Study...

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Short Answers to Lecture 7 Study Questions 1. What are the functions of voltage-gated Na channels, and voltage-gated K channels in producing an action potential? What is the meaning of ‘inactivation ‘of a V-gated Na channel, what is its function? Voltage-gated Na channels depolarize the membrane very quickly, by a positive feedback mechanism – more depolarization causes more channels to open, which causes more flow of Na ions in, which causes more depolarization. These channels close themselves (inactivate) after being open for some time, ending the positive feedback. Voltage-gated K channels repolarize the membrane, opening more slowly than the Na channels do. They provide negative feedback – more depolarization causes more opening of V-gated K channels, which allows more flow of K ions out of the membrane, which causes less depolarization. 2. In what way does the structure of a primary afferent neuron differ from the structure of many CNS neurons? Primary afferent neurons have a receptor ending or cell and a single long axon that carries action potentials to distant cells in the CNS, transmitting at the CNS end through a syapse. There is no dendritic tree, and the cell body is often found on a stalk connected to the long axon. 3. Give examples of sensory transduction in which the receptor membrane or cell: a. uses ion channels to transduce chemical potential into electrical potential Sourness receptors on the tongue have H+ channels that pass through ion channels to depolarize the receptor membrane. b. uses strain-sensitive channels to transduce mechanical energy into an electrical potential T ouch sensors in the skin) have Ca channels that open in response to membrane strain, allowing Ca to flow into the cell, depolarizing it. c. uses ligand-binding channels to transduce chemical energy of specific molecules into
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This note was uploaded on 05/07/2010 for the course INTEG BIO 132 taught by Professor Lehman during the Spring '10 term at University of California, Berkeley.

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lecture7 sq key - Short Answers to Lecture 7 Study...

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