The Nervous System: Membrane Potential
The Nervous System: Membrane Potential
1.
Record the intracellular and extracellular concentrations of the following ions (mM/L):
Intracellular
Extracellular
Sodium (Na+)
Potassium (K+)
Chloride (Cl–)
2.
Excitable cells, like neurons, are more permeable to ___________ than to ___________.
3.
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 ___________
4.
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? _____________________
5.
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.
6.
In an excitable cell, also permeable to Na+ and Cl–, the gradients mentioned in question 4 would both tend to move Na+ ___________ the cell.
7.
Would the gradients in question 4 promote or oppose the movement of Cl– into the cell?
a.
b.
8.
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.
9.
What compensates for the movement (leakage) of Na+ and K+ ions? ______________
10.
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+ ___________
b.
↓ extracellular fluid concentration of K+ ___________
c.
↑ extracellular fluid concentration of Na+ ___________
d.
↓ number of passive Na+ channels ___________
e.
open voltage-gated K+ channels ___________
f.
open voltage-gated Na+ channels ___________
1.
Record the intracellular and extracellular concentrations of the following ions (mM/L):
Intracellular
Extracellular
Sodium (Na+)
Potassium (K+)
Chloride (Cl–)
2.
Excitable cells, like neurons, are more permeable to ___________ than to ___________.
3.
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 ___________
4.
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? _____________________
5.
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.
6.
In an excitable cell, also permeable to Na+ and Cl–, the gradients mentioned in question 4 would both tend to move Na+ ___________ the cell.
7.
Would the gradients in question 4 promote or oppose the movement of Cl– into the cell?
a.
b.
8.
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.
9.
What compensates for the movement (leakage) of Na+ and K+ ions? ______________
10.
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+ ___________
b.
↓ extracellular fluid concentration of K+ ___________
c.
↑ extracellular fluid concentration of Na+ ___________
d.
↓ number of passive Na+ channels ___________
e.
open voltage-gated K+ channels ___________
f.
open voltage-gated Na+ channels ___________