9. The cardiac myocyte action potential

Rapid depolarization begins when _ increases and _ enters the cell

sodium permeability, sodium

What happens during the plateau?

potassium permeability decreases while calcium permeability increases

What helps the membrane potential stay stable?

Calcium

When does repolarization occur?

occurs as calcium permeability falls and potassium permeability increases, returning the

membrane potential toward its resting level

Is the cardiac action potential long or short? Why?

Long because the contraction must be long enough to pump blood and because of the long absolute refractory period

What does the long absolute refractory period do for the heart muscle?

prevents a second action potential from summing with the first contraction.