Question

Describe the process of generation of action potential in the heart. Include ions involved.

Answer 1

ANSWER: Cardiac action potential is different from that of skeletal muscle action potential. Cardiac action potential also happens through 4 phases. In phase 0, there is rapid transient influx of sodium ions. Later sodium ions are inactivated, combined with the efflux of potassium. This influx of sodium ions causes the depolarisation. After depolarisation, there is a plateau phase, which occurs due to the efflux of potassium ions and influx of calcium ions are counterbalanced. Following it there occurs more efflux of potassium ions than influx of calcium ions,due to delayed rectifier potassium ion channels. The plateau phase is the phase 2 of the cardiac action potential. The following phase is the phase 3. In phase 4, resting membrane potential is achieved due to the efflux of potassium ions.