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19 Cards in this Set

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