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19 Cards in this Set
- Front
- Back
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Define electric potential (word def):
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amount of work required for charged particles (ions) to move against resistance
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Which ion, Na or K is more permeable, and by how much?
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K is 100x more permeable than Na
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Which ion contributes the most to resting membrane potential?
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K
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Define the Nernst Equation:
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EMF = -61 log [K]i/[K]o, EMF is electromotive force in Volts
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If there is a higher concentration of positive ions outside the cell than inside the cell (Ex. Na), would the electric potential be positive or negative?
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positive, + ions go down their concentration gradient into the cell leading to a buildup of positive charge inside the cell
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If there is a lower concentration of positive ions outside the cell than inside the cell (Ex. K), would the electric potential be positive or negative?
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negative, + ions go down their concentraion out of the cell leading to a deficit of + ions inside the cell
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Why does potassium have a greater influence on resting membrane potential than sodium?
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It is more permeable. See Goldman's eqn.
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What is the biggest consumer of ATP in the cell?
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Na/K ATPase
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Is a resting cell at steady state or equilibrium?
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steady state, takes energy input via Na/K ATPase to maintain membrane potential
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How many and what ions does the Na/K ATPase exchange?
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3 Na out, 2 K in
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What is action potential propagation mediated by?
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"transient changes in permeability of membrane to Na and K.
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What happens during depolarization?
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cell becomes more positive due to Na influx
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What happens to reverse the depolarization?
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K channels open more slowly. K leaves cell, reestablilshing negative membrane potential
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How many gates does a sodium channel at like it has?
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2 gates
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What are potential drugs targeting sodium channels?
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Antiarrhythmic drugs, bind sodium channels in specific states.
Lidocaine |
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How many gates does a potassium channel at like it has?
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1 gate
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When does peak potassium conductance occur?
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after peak sodium conductance, it reestablishes the negative resting membrane potential
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What does charybdotoxin (scorpion venom) target?
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blocks specific class of voltage gated sodium channels
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What does the effect of any ion channel blocker depend on?
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Type of channel bound. Proportion of channels bound. Concentration of blocker. Tightness of binding
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