The Nervous System: Membrane Potential
Record the intracellular and extracellular concentrations of the following ions (mM/L):
Excitable cells, like neurons, are more permeable to ___________ than to ___________.
How would the following alterations affect the membrane permeability to K+? Use arrows to indicate the change in permeability.
a. An increase in the number of passive K+ channels ___________ b. Opening of voltage-gated K+ channels ___________
c. Closing of voltage-gated K+ channels ___________
a. What acts as a chemical force that pushes K+ out of the cell? ___________ b. What force tends to pull K+ back into the cell? _____________________
When the two forces listed above are equal and opposite in a cell permeable only to K+, this is called the _________________________ potential for K+ which is ___________ mV.
In an excitable cell, also permeable to Na+ and Cl–, the gradients mentioned in question 4 would both tend to move Na+ ___________ the cell.
Would the gradients in question 4 promote or oppose the movement of Cl– into the cell?
Since the neuron is permeable to Na+ as well as K+, the resting membrane potential is not equal to the equilibrium potential for K+, instead it is ___________ mV.
What compensates for the movement (leakage) of Na+ and K+ ions? ______________
What will happen to the resting membrane potential of an excitable cell if: (Write pos or neg to indicate which way the membrane potential would change.) a.
↑ extracellular fluid concentration of K+ ___________
↓ extracellular fluid concentration of K+ ___________
↑ extracellular fluid concentration of Na+ ___________
↓ number of passive Na+ channels ___________
open voltage-gated K+ channels ___________
open voltage-gated Na+ channels ___________...
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