Predict the effects of hypocalcemia (low blood calcium ion levels) on the strength and length of contraction in a cardiac contractile cell
What will be an ideal response?
Calcium ions normally enter the cardiac contractile cells as potassium ions continue to leave during the plateau phase in order to slow the heart rate and allow the heart to fill with blood. Normally, as calcium ions enter and potassium ions leave, the net membrane potential remains largely unchanged. However, in the case of hypocalcemia, the balance of ions entering and leaving would be disturbed. Since more potassium ions would be leaving than calcium ions entering, the cardiac contractile cell would not able to maintain a net charge of 0 mV. Thus, the length of the action potential would be shorter, the contraction potentially less forceful, and the heart would have less of an opportunity to fill with blood between action potentials.
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