Why is skeletal muscle capable of tetanic contractions while cardiac muscle cannot?

• A. Skeletal muscle cannot maintain contraction.
• B. Cardiac muscle can tetanize because of its plateau.
• C. Cardiac muscle uses a different calcium mechanism; not relevant.
• D. Skeletal muscle can summate contractions due to a shorter refractory period; cardiac has a long plateau and long refractory period preventing tetanus.

Answer: (D)