A muscle response to stimulus is shown in the diagram below

A muscle response to stimulus is shown in the diagram below. cardiac muscles cannot undergo complete tetanus. Why?

Solution

According to given graph it is very clear that cardiac muscles have long refactory period. It have its own action potential which lasts longer than the contraction.when Ca+ gate open, Ca+ ions influx after that Na+ ions influs and then K+ ions efflux takes place. All these simultaneously preventing change in membrane potential so it can not contract again as it is in totally relax condition.