Multiple choice

Which among the following statements regarding the cardiac muscles of the body is incorrect?

  1. The diad is located at the sarcomere Z-line.

  2. The diad juxtaposes an inlet for the action potential near a source of Ca2+ ions.

  3. Intercalated discs connect the single cardiac myocytes to an electrochemical syncytium.

  4. Cardiac muscle requires intracellular calcium ions for contraction to occur.

  5. Cardiac muscle cells rely on an available blood and electrical supply to deliver oxygen.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In contrast to skeletal muscle, cardiac muscle requires extracellular calcium ions for contraction to occur. Like skeletal muscle, the initiation and upshoot of the action potential in ventricular muscle cells is derived from the entry of sodium ions across the sarcolemma in a regenerative process.

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