15

Question 1

Resting potential

Answer 1

The difference in electric potential between inner and outer side of the cell membrane in a physiologically resting state. Resting potential is observed in all living cells. It can be measured in needle electrodes and fluorescent labels. Typical values:
Animal cells ~ -70 mV
Bacterial, plant cells ~ -200 mV

Question 2

Factors responsible for the resting potential: #1

Answer 2

Asymmetric distributon of ions inside and outside cells

Question 3

2

Answer 3

Open К+ channels- Resting potential according to Bernstein (Nernst‘s equation). Neglects the contribution of all ions except for K+.

Question 4

3

Answer 4

Considering the real membrane permeability for К+ Na+ Cl-

PK+ : PNa+ : PCl- = 1 : 0.05 : 0.5

Question 5

Equation of Goldman

Answer 5

Used in cell membrane physiology to determine the reversal potential across a cell’s membrane, taking into account all of the ions that are permeant through that membrane:

Question 6

4

Answer 6

Donnan potential = Equilibrium potential due to impermeable membrane for large charged molecules. Part of the small ions are attracted at the side with the large ions: colloid osmotic effect.

Question 7

5

Answer 7

Electrogenic active transport - P class pump = K+/Na+ -pump = Present in the membranes of all cells, especially in the membranes of kidney cells. Maintains low concentration of Na+ and high concentration of К+ in the intracellular space (К+ is needed for supporting enzyme activity in the cytoplasm). Inhibition by specific cardiac glycosides.