The refractory period of cardiac muscle is much longer than that of skeletal muscle. Why is this a desirable functional property?

Video transcript

Welcome back, everyone. Here's our next problem. Cardiac muscle has a unique property known as auto rhythmicity, which means A, it can contract without any external stimulation. B it can contract faster than skeletal muscle. C, it can adjust its contraction strength as needed or D it can relax and contract simultaneously. Well, if we can't remember off the top of our head, what auto rhythmicity is? We can get a clue just in the very word that prefix, auto usually means self. And then of course, rhythmicity, we think of rhythm, self rhythm. So that leads us to our correct answer, which is choice. A, it can contract without any external stimulation. So it doesn't need a signal from outside. It governs its own contractions. And this is because the heart generates its own electrical impulses to initiate contractions without an external stimulus from the nervous system. Usually when we think of electrical uh electrical impulses, they're coming from the nervous system, but not in the case of the heart. Let's just look at our other answer. Choices. Choice B, it can contract faster than skeletal muscle is incorrect. It generally contracts slower or more slowly than the skeletal muscle C it can adjust its contraction strength as needed. Well, there can be some adjustment in its contraction strength, but that's not governed by the principle of auto rhythmicity that's regulated by the autonomic nervous system. So that's why that's not correct. Even though it's a true statement, it's not related to auto rhythmicity. So we'll cross that off and then choice d it can relax and contract simultaneously. No, it does not relax and contract simultaneously. It has a specific sequence of a contraction relaxation cycle governed by again, its own auto rhythmicity. So again, the unique property of cardiac muscle, cardiac muscle, auto rhythmicity means choice a it can attract without any external stimulation. See you in the next video.