An increase in extracellular calcium generally increases
A)the heart rate.
B)the force of contraction.
C)autonomic stimulation of the heart.
D)sodium channel opening.
E)the frequency of the action potentials.

Question

Quizplus · Accepted Answer

An increase in extracellular calcium generally increases the force of contraction of cardiac muscle cells. This occurs because calcium ions bind to troponin, which causes a conformational change in the tropomyosin complex that allows interaction between actin and myosin filaments, leading to muscle contraction. An increase in extracellular calcium does not directly affect heart rate, autonomic stimulation of the heart, sodium channel opening, or the frequency of action potentials.

An Increase in Extracellular Calcium Generally Increases