Why can't tetanus occur in the heart?
A)There are no distinct motor units in the heart.
B)There is inadequate oxygen supply via the coronary circulation to metabolically support a sustained contraction.
C)The refractory period in cardiac muscle lasts almost as long as the contraction.
D)The heart contracts with maximal force every beat so it is impossible to increase the strength of its contraction.
E)Vagal stimulation slows down the heart rate to prevent summation of contractions.

Question

Quizplus · Accepted Answer

The refractory period in cardiac muscle lasts almost as long as the contraction, which means that there is not enough time for the muscle to undergo multiple contractions before it is refractory again. Therefore, tetanus cannot occur in the heart.

Why Can't Tetanus Occur in the Heart