Membrane Potentials

Question 1

Membrane permeability of K, Ca, Na

Answer 1

Membrane somewhat permeable to K, but less to Ca and Na.

Question 2

Movement across membrane governed mostly by:

Answer 2

Na/K ATPase pump (3 Na out, 2 K in)

K leak channels (K leak out)

Question 3

Diffusion forces vs. Electrostatic forces

Answer 3

Diffusion force: ions travel down concentration gradient.
Electrostatic force: charge based.
The sum of both is electrochemical force.

Question 4

Equilibrium potential

Answer 4

Membrane potential when electrical and chemical forces are equal.

Question 5

Cell membrane polarization (4)

Answer 5

Polarization - deviation from 0 mv.
Depolarization - when membrane potential becomes less negative (goes up).
Hyperpolarization - when membrane potential becomes more negative.
Repolarization - when membrane potential returns to resting potential.

Question 6

Key properties of action potentials (3)

Answer 6

1. All or none
2. Propagating or self-reinforcing.
3. Non-decremental