Membrane Potentials

Question 1

What is the resting membrane potential?

Answer 1

Establishes a starting point for a cell to be potentially excited

Question 2

What is the typical ion concentration of potassium inside the cell?

Answer 2

155 mM (HIGHER INSIDE)

Question 3

What is the typical ion concentration of Potassium outside of the cell?

Answer 3

4.5 mM

Question 4

What is the typical ion concentration of sodium outside the cell?

Answer 4

145 mM

Question 5

What is the typical ion concentration of sodium inside the cell?

Answer 5

12 mM (LOWER INSIDE)

Question 6

What concentration gradients does the Na/K ATPase pump typically establish?

Answer 6

Move Potassium IN
Move Sodium OUT

(High K+ inside the cell, low K+ outside)

Question 7

What ion is the resting membrane potential primarily dependent on?

Answer 7

The permeability of the plasma membrane to POTASSIUM ions

Question 8

What ion is the membrane more permeable to? K, Ca, or Na?

Answer 8

Potassium

Question 9

What is the main function of Na/K ATPase?

Answer 9

• Maintain concentrations in proper place

Exchange 3Na OUT and 2 K IN (against concentration gradients, so requires energy)

Question 10

What are the key characteristics and functions of K+ Leak channels?

Answer 10

Open all the time, permitting unregulated passage of ions.

Passively, K+ is more likely to leave the cell

• Main contributor to the permeability of the plasma membrane to K+ ions!

Question 11

Resting Membrane Potential of Muscle cells?

Answer 11

-80 to -90 mv

Question 12

Resting membrane potential of smooth muscle?

Answer 12

-60 mv

Question 13

Resting membrane potential of neurons?

Answer 13

-60 to -70 mv

Question 14

What two forces act on ions to develop membrane potential?

Answer 14

Diffusion forces (Chemical)
- concentration gradient based

Electrostatic forces (Electrical)
- charges based