Week 2: Module 1 Pt.2

Question 1

During a cardiac muscle action potential what happens?

Answer 1

1. Depolarisation: (inside of cell is more “-“) Na+ goes into cell.
2. Plateau: K+ rushes out and Ca2+ rushes in.
3. Repolarisation: (inside of cell is less “-“) Ca2+ channels close, K+ channels stay open and K+ slowly continues to leak out.

Question 2

What happens during pacemaker action potential?

Answer 2

1. Leaky Na+ channels leak until threshold is reached.
2. Depolarisation: Ca2+ rushes in.
3. Repolarisation: Ca2+ channels close and K+ channels stay open and continue to leak.

Question 3

During the cardiac muscle action potential, why is there a plateau?

Answer 3

While K+ comes out, making the cell more “-“, Ca2+ is also rushing into the cell, making a plateau. This also makes sure that the heat does not cramp during contractions.