Tetanic contraction following rapid stimulation occurs in which region of cardiac muscle? A. atrium B. Sino-atrial node C. Bundle of His D. All of the above E. None of the above

• None of the above

Explanation:

• Tetanic contraction does not occur in the cardiac muscle. It is a muscle contraction that is evoked when the motor nerve which innervates a skeletal muscle emits an action potential at a very high rate.
• The cardiac muscle has long absolute refractory period due to its fibers while skeletal muscle lacks these fibers. This absolute refractory period is as long as the contraction itself.