Question

In: Anatomy and Physiology

Which type of muscle cell exhibits a longer refractory period?

Which type of muscle cell exhibits a longer refractory period?

Solutions

Expert Solution

Cardiac muscle cells exhibits a longer refractory period. It is necessary for the cardiac muscle cells to have a longer refractory period, because if they were short, the heart could cause tetanic contraction/summation during which the muscle is stimulated so quickly that it has no chance of relaxing between stimuli.

Three major types of cardiac muscle are,

  1. Atrial muscle-similar to skeletal muscle but with a longer contraction duration

  2. Ventricular muscle-similar to skeletal muscle but with a longer contraction duration

  3. Specialized muscle of the cardiac conducting system-few contractile fibers, so limited contractility: important because of their key role in cardiac electrical excitation

After the initiation of an action potential, the heart cell can not initiate another action potential for some time. This time period is called the refractory period, which lasts approximately 250 ms and it helps to protect the heart.


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