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Thread: Heart Muscle

  1. #1 Heart Muscle 
    Forum Freshman Patrick_94's Avatar
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    A few years ago in science, we were doing the heart and the teacher said that it was a muscle, and I asked doesn't it tire, and she said no, so I asked why aren't all our muscles like that, and she basically told me to shut up (ie she didn't know). Would it be possible to get muscles like this? No fatigue or tiredness?


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  3. #2  
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    It seems to be the mitochondria, according to this article.
    http://indianapublicmedia.org/amomen...art-get-tired/
    Because it has not been necessary in the course of evolution for humans to be able to flex our skeletal muscles for prolonged periods of time, the total volume of skeletal muscle contains an average of only 1 to 2% mitochondria. This is an entirely sufficient energy source for such intermittent muscular tasks as walking or running. The total volume of the heart, by contrast, is between 30 and 35% mitochondria.

    That massive amount of energy-generators means cardiac muscle, in a healthy state, need never rest: there is always some energy being transferred to the muscle at the same time that more energy is being derived from caloric intake. And always just in time for that next beat.


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  4. #3 Re: Heart Muscle 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Patrick_94
    A few years ago in science, we were doing the heart and the teacher said that it was a muscle, and I asked doesn't it tire, and she said no, so I asked why aren't all our muscles like that, and she basically told me to shut up (ie she didn't know). Would it be possible to get muscles like this? No fatigue or tiredness?
    I imagine it would require a lot more energy than we normally take in. Perhaps not as much a problem for a modern human, but a few thousand years ago it would have been prohibitive. The increased calorie intake would probably bring problems with it in itself too.
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  5. #4  
    Forum Isotope Bunbury's Avatar
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    What a great question, and what a pity the teacher couldn't say "I don't know" and make it a homework assignment to find out.
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  6. #5  
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    I think the teacher was also a bit inaccurate by saying "no" to the question of whether or not the heart tires. It actually does, it just generally takes decades to do so. Check out things like congenital heart failure or other cardiac issues.

    My sense is that the question the OP was asking relates more to lactic acid buildup than to exhaustion.

    EDIT: After reading Harold's link, I did some more reading and realized that mitochondria actually helps metabolize lactate for energy, so I think his reply is related, but more on point than my comment about lactic acid buildup. It gets closer to the root cause than I did.
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  7. #6  
    Forum Freshman Patrick_94's Avatar
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    This mitochondria, the page says it's 1-2% in skeletal muscles and around 35% in cardiac muscles, could you inject it into skeletal muscles? Or do something similar to radically increase mitochondria?
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  8. #7  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Patrick_94
    This mitochondria, the page says it's 1-2% in skeletal muscles and around 35% in cardiac muscles, could you inject it into skeletal muscles? Or do something similar to radically increase mitochondria?
    That alone wouldn't do much for you. The cell types are different- they're expressing a host of different genes. I'm guessing that without the appropriate gene product infrastructure in place, the extra mitochondria will either remain dormant or simply die off. Plus, as I said before, if you increase the energy needs of human skeletal muscle, that energy will have to come from somewhere.
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  9. #8  
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    Endurance training can increase mitochondrial biogenesis in skeletal muscle.
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