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19 Cards in this Set

  • Front
  • Back
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]
E of K
-86 mv
conversion factor for ln to log10
E of Na
60 Mv
E of Ca
240 Mv
E of Cl
Most neurons - diffuses passively -> = resting membrane potential
In neurons where Cl- [conc] actively maintained= -66 mV to -75 mV
What determines the direction and lagnitude of the electrochemical driving force that causes ion movement?
The difference between the instantaneous membrane potential and the equilibrium potential
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
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
What is the spread of charge along the membrane by passive mechanisms called?
electrotonic propagation /
electrotonic conduction
What is the resting membrane potential in non-excitable cells?
Between -10 mV and -30 mV
Which ions is the membrane permeable to at rest (the main 3)
K+, Na+, Cl-
What is the net ion flow at rest?
Goldman equation
V=60log10 ( Pk[K out] + PNa[Na out]/
Pk[K in] + PNA [Na in] )
Are any voltage gated channels open at rest?
Yes. Some V.G. K+ (rest. potential is in voltage range)
Few V.G. Na+ (prob. of opening isn't 0)
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
What is hyperpolarization?
Inside of membrane becomes more negative
What is depolarization?
Inside of membrane becomes more positive
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