3 fascinating facts about the heart
Have you ever stopped to think that the heart muscle doesn't get sore like the legs and arms do?
When subjected to certain types of exercise, our arm and leg muscles - generally speaking, the so-called skeletal muscles - can become sore.
The tiny strands of protein that form muscles, when stimulated, slide over each other, causing contraction and stretching movements - which, in turn, allow us to run, jump and lift, for example.
When the effort is greater than usual, the muscles suffer minor damage. And that pain we feel the next day is the result of the repair process undertaken by our cells - which, by the way, contributes to making the muscles stronger.
But have you ever wondered why, even if it's a muscle, the heart doesn't hurt like the others? What is special about the heart?
1. Always beating
The heart is the first structure to form in the uterus.
"In the beginning, it's basically a tube," cardiologist Rohin Francis explains to the BBC.
End of Podcast
"That tube, through a really amazing origami folding process, eventually becomes the mature heart."
From very early on in embryonic development a primitive heart beats.
Gradually, as we develop in the womb, it becomes more complex, eventually forming the four-chamber structure we are all familiar with.
Thus, almost from the initial moment until death is always knocking. That's why so early in pregnancy you can hear the fetus's heartbeat - that sound that often moves parents during prenatal consultations.
And that's not the only fascinating aspect, says the cardiologist.
"If you put a culture of heart cells in a Petri dish, even a few, they will not only spontaneously start beating, they will also synchronize with each other."
"They have an intrinsic tendency to pulsate."
For this, cells need a lot of energy.
Heart muscle works uninterruptedly
2. Full of energy
"Compared to skeletal muscles, cardiac cells are much more efficient," explains Francis.
"They have a more robust supply of mitochondria, so they are extremely energetic cells."
Mitochondria are a kind of energy factory for the cell.
"They create the ATP that we use to power all of our cellular metabolism."
Adenosine triphosphate (ATP) is an organic compound found in all known life forms. It provides energy for carrying out many processes in cells.
And energy is what it takes to move any muscle, especially the heart, which, even at rest, is always working hard.
Your cells need to be able to keep beating around the clock, and for that they need much higher levels of ATP than skeletal muscles.
There is something, however, that they have less of.
3. Few nerves
"When you're talking about the sensation of pain in the skin or muscles, it's very important to be able to pinpoint exactly where the pain is coming from. So the body has a high density of sensory nerves that supply these parts of the body so that you can identify exactly where the problem comes from", details the cardiologist.
In the case of internal organs, he adds, while it is important for organs to be able to tell the brain that something is wrong, the information is not so accurate.
"The density of the sensory nerve is much lower."
It sounds worrying, but it would probably be worse if it were different. That's because if it weren't for the fact that we have far fewer nerve endings in our heart, we would constantly "feel" it and be aware of every beat... can you imagine?
As wonderful as the heart is, however, it has one major drawback.
Does not regenerate when damaged
"The heart is terrible at fixing itself," points out Sanjay Sinha, a senior fellow at the British Heart Foundation and professor of cardiovascular regenerative medicine at the University of Cambridge.
"When the average person has a heart attack or a heart injury, what usually happens is that part of the heart muscle dies and never recovers."
"It repairs itself by forming a scar - but the lost muscle won't come back, which ends up getting in the way of the contraction movement. That's basically why it's so serious."
What is it about heart muscle tissue that doesn't allow it to repair itself in the same way that skeletal muscle does?
The reason lies in the "intrinsic tendency to hit" highlighted earlier.
In order for a tissue to repair itself, its cells need to multiply, and in order for them to multiply, they need to divide.
"Cardiac cells are specialized in contracting, so they are full of contractile myofilament proteins", says the expert.
If one of these cells split to form another, "you would have to take everything apart and then reassemble all the contractile machinery."
In the meantime, however, the cells would not be able to contract - something the heart cannot afford to do, as it is in continuous use.
That is, the fact of not being able to stop inhibits the heart's ability to repair itself.
"If you look very closely, you can see maybe 1% of heart muscle cells dividing over the course of a year. That's very, very low and not enough to regenerate the heart," says Sinha.
So the best, of course, is to take care of him. Like?
"What we usually advise at the moment - and this is just a guideline - is to do some activity that leaves you a little breathless for at least half an hour three times a week", highlights cardiologist Rohin Francis.
*This text is based in part on the episode "The painless heart" from the BBC series "The curious cases of Rutherford & Fry" )
No comments:
Post a Comment