Why isn’t our heart tired after beating for so long?
In: 24
Your heart is designed to beat non-stop for ~75 years at a gradually-reducing average rate (~160bpm in utero down to ~65bpm when you reach “old age”)
All other things being equal, you’ve got X many beats before it’s done – so your heart *does* “get tired”, it just takes a really long time to do so
The muscle the heart is made of is different from regular muscle fibre. Normal muscles store energy inside them which gets used up as you exercise and (slowly) replaced by chemicals carried by the bloodstream. They get tired if you use up that energy faster than the blood can provide it. Heart muscle, on the other hand, is directly fed by the bloodstream for sustenance and oxygen. This means it never tires, but on the other hand, means things go very badly wrong if the blood supply is interrupted even briefly, as happens when you have a heart attack.
Cells contain what are known as mitochondria which are nicknamed the powerhouse of the cell. This is because they provide the cell with chemicals which are used to power the cell. The mitochondria can only produce so much of these chemicals so fast.
Heart muscle cells contain a lot more mitochondria than other cells. This makes them unlikely to run out of the chemicals to keep them going so heart muscle is unlikely to run out of energy.
Latest Answers