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Monday, October 12, 2009

Why heart muscles don't get tired?

When any muscle contracts continuosly for some time , it becomes fatigued and sore..Further contraction is possible only after a period of rest..But how the muscles of heart able to contract continuously without fatigue?
Answer:
Constant electrical stimulation.
They are very strong panda!
i am told it rests between beats...
the heart muscle has a long refractory period i.e. the period during which it does not respond to a second stimulus however strong it might be. So the cardiac muscle responds to 1 stimulus at a time thereby not exhibiting the property of fatigue.
The heart muscle is one of the strongest muscles in our body because it can keep going as long as it is provided with oxygen from out blood. although it does "rest" when we sleep, because our heart rate slows, it is not rest as the other muscles in our body would need it. It is similar to how the neck muscles do not tire of holding our heads up all day. It is a muscle with high stamina which evolved because otherwise we would be a tiny bit dead.
If you noticed the composition of the heart muscle is different from other striated muscles. The myoglobin is arranged differently, and the electrical pattern includes two phases.The rythm of the contractions, permit the sarcoplasmin reticulum to recharge, and the mitochondrial activities of ATP metabolism, utilizes glycerides instead of glucose.These differences account for less exhaustion. However persons with specific cardiomyopathies may die earlier than other, due to exhaustion even at rest.
the heart consists of mainly slow twitch fibers.
It rests at the same time the body rests, mostly when the body is sleeping, but also when you sit and wait and do nothing. Like when you kick back and lay in the sun on the beach or in the
lazyboy recliner.
it buit to do it so it can pump untill you die

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