Why the heart doesn’t get tired from being active 24/7 but other muscles do?
In: Biology
If you look at it closely, the heart is not working all the time.
The heart can be said to consist of four chambers, namely two atria and two ventricles. The two pairs of chambers work in such a way that either the atria or the ventricles or both get a rest at a given time:
Every single heartbeat includes three major stages: atrial systole, ventricular systole, and complete cardiac diastole.
Atrial systole is the contraction of the atria that causes ventricular filling.(The ventricles ate realxed here) Takes about 0.1seconds
Ventricular systole is the contraction of the ventricles in which blood is ejected into the pulmonary artery or aorta, depending on side.( The atria are relaxed here)Takes about 0.3 seconds
Complete cardiac diastole occurs after systole. The blood chambers of the heart relax and fill with blood once more, continuing the cycle.
(Both are relaxed during this point)Takes about 0.4 seconds.
So in a cardiac cycle of about 0.8s the
·Ventricles are resting for about 0.5s
·Atria are resting for about 0.7s
Some more info:
https://courses.lumenlearning.com/boundless-ap/chapter/physiology-of-the-heart/
The special nature of the heart muscles have been explained very well by the other comments, so I will refrain from talking about that.
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