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19 Cards in this Set
- Front
- Back
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Nernst equation at 35 C
for cations for anions |
For cations
60 log10 ([conc. out]/[conc. in] For anions 60 log10 ([conc. in]/[conc. out] |
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E of K
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-86 mv
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conversion factor for ln to log10
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2.303
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E of Na
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60 Mv
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E of Ca
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240 Mv
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E of Cl
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Most neurons - diffuses passively -> = resting membrane potential
In neurons where Cl- [conc] actively maintained= -66 mV to -75 mV |
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What determines the direction and lagnitude of the electrochemical driving force that causes ion movement?
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The difference between the instantaneous membrane potential and the equilibrium potential
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1. What is the definition of an electromotive force?
2. What is an electromotive force analogous to? |
1. Any mechanism that is a source of electrical potential
2. a battery |
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1. What is a capacitor? (How does it roughly work?)
2. What part of a cell acts as a capacitor? |
1. Two electrical conductors in close apposition but separated by an insulator can store a relatively large amount of charge.
2. The membrane |
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What is the spread of charge along the membrane by passive mechanisms called?
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electrotonic propagation /
electrotonic conduction |
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What is the resting membrane potential in non-excitable cells?
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Between -10 mV and -30 mV
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Which ions is the membrane permeable to at rest (the main 3)
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K+, Na+, Cl-
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What is the net ion flow at rest?
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0
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Goldman equation
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V=60log10 ( Pk[K out] + PNa[Na out]/
Pk[K in] + PNA [Na in] ) |
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Are any voltage gated channels open at rest?
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Yes. Some V.G. K+ (rest. potential is in voltage range)
Few V.G. Na+ (prob. of opening isn't 0) |
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1. Are any Voltage gated Na channels open at rest?
2. How do we know? |
1.Few Na+ (prob. of opening isn't 0)
2. Tetrodotoxin (TTX) blocks V.G. Na channels - creates small hyperpolarization |
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What is hyperpolarization?
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Inside of membrane becomes more negative
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What is depolarization?
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Inside of membrane becomes more positive
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1. What is the contribution of the Na+/K+ pump at any given time? Why?
2. How do we know? |
1. Small - 2-5 mV d/t # of ions crossing membrane at rest is small compared to # of ions on either side
2. Digitalis poisons pump, most neurons fx well for hours afterward |
