Question

What happens to the cardiac muscle cells when there is a spike of any physical activity?

• A. Rapid influx of $K^{+}$ ions into the cell
• B. Rapid influx of $N{a}^{+}$ ions into the cell
• C. Rapid exit of $N{a}^{+}$ ions from the cell
• D. Rapid influx of $C{a}^{+2}$ ions into the cell

Answer 1

The correct option is B

Rapid influx of $N{a}^{+}$ ions into the cell

Rapid influx of $N{a}^{+}$ ions into the cell

These spontaneously changing membrane potentials trigger the contractions of the heart. During the rapid depolarization phase $N{a}^{+}$ channels on the membranes of the cells open up, and the influx of positive sodium ions, $N{a}^{+}$ helps to depolarize the cell further.