Electrical activity of the heart

Question 1

How do changes in concentration regulate electrical activity of the heart?

Answer 1

• The concentration of K+ is high within the cell and low outside. This creates a chemical gradient for K+ to diffuse out of the cell.
• The gradients for Ca++ and Na+ favor an inward diffusion.
  The permeability of the cell membrane to a given ion is described by conductance.

Question 2

what is Nernst equation?

Answer 2

E= RT/zF . ln(Co/Ci)
where:
R:gas constant
T: temperature (K)
z: charge/ion
F: faraday constant
c: concentration

Question 3

what 3 things determine the membrane potential?

Answer 3

1.Concentration gradients for Na+, K+ and Ca2+
2. Their permeability (electrical conductance)
3. Electrogenic ion pumps