Chapter 5

Question 1

When a membrane is permeable to several different ions, the diffusion potential that develops depends on three factors:

Answer 1

(1) the polarity of the electrical charge of each ion
(2) permeability of the membrane (P) to each ion
(3) the concentrations (C) of the respective ions on the inside (i) and
outside (o) of the membrane

Question 2

Origin of the Normal Resting Membrane Potential

Answer 2

1. Contribution of the Potassium Diffusion Potential
2. Contribution of sodium diffusion through the nerve membrane
3. Contribution of Na+ and K+ pump

Question 3

Causes of the plateau

Answer 3

1. In heart muscle, two types of channels enter into the depolarization process: (1) fast channels (2) slow channels
2. voltage-gated potassium channels are slower than usual to open

Question 4

Rhythmical discharges cause

Answer 4

(1) the rhythmical beat of the heart, (2) rhythmical peristalsis of the intestines
(3) such neuronal events as the rhythmical control of breathing