Why is cardiac muscle better adapted for the action of the heart than is skeletal muscle?
Skeletal muscle and cardiac muscle are both striated tissue. However, the specific adaptations of cardia tissue allow it to remain contracted for a slightly longer time–but not tetanus (sustained muscle contraction). The calcium release from muscle depolarization is allowed to stay in the muscle slightly longer, letting the myosin bind to the actin molecules. Once calcium is reabsorbed, the myosin can no longer hold onto the actin and the muscle relaxes. This longer contraction allows blood to be efficiently pumped through the heart. Also, skeletal muscle’s calcium channels are only activated by depolarization from an action potential from a connecting nerve. Cardiac muscle contracts because of a signal recieved from the pacemaker located at the top side of the right atrium. The cardiac muscle tissue can beat on it’s own and does not require signals from the brain to contract. (unconscious operation). Hope that helps!
