Exam 2 Powerpoint 7 Flashcards
Reversal Potential
Point at which a move in potential in either direction will have opposing effects.
Rule #1
Ions only move through open channels
Rule #2
Ions only move to seek their equilibrium
Rule #3
Ion movement causes a current that alters the neurons potential
Hyperpolarize
+ charge exit or - charge enters
Depolarize
+ charge enter or - charge leaves
In a real neuron at rest, it is more permeable to
Potassium K+
In a real neuron at AP, it is more permeable to
Sodium Na+
Resting potential is mostly due to
K+, if it was entirely it would be exactly equilibrium potential
Each ion pushes membrane towards its..
reversal potential
Strength of ion push depends on
permeability, # of channels open
Goldman equation
P(K out)+P(Na out)+P(Cl in)/
P(K in)+ P(Na in)+P(Cl out)
58 x Log(^)
At rest:
PK:PNa=
PK:PCl=
1:0.03
1:0.1
During AP:
PK:PNa=
PK:PCl=
1:15
1:0.1
What happens to the resting membrane potential if we change the outside K+ concentration?
Higher: more +
Lower: more -
What is responsible for the resting membrane potential?
K+
At rest, Cl and Na have________ permeability
Small
Most cells, not just neurons have a membrane potential that is generally______
Negative
Muscle cells are more permeable to _____than other neurons so _____is more important than
____ for the resting membrane potential.
Cl Cl K
What happens to the
action potential if we change the
outside Na+ concentration?
High, high
Low, low
At rest, neuronal membranes more permeable to___ than___
K+ Na+
At AP, neuronal membranes more permeable to___ than___
Na+ K+
During repolarization, K+ ____ permeable than Na+
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