According to 2 sources I've read, in contrast to skeletal myocytes, cardiac myocytes need calcium to diffuse in to result in contraction. One source says that they need large amounts of calcium to diffuse in through T-tubules as the cardiac sarcoplasmic reticulum is not as well developed as the skeletal sarcoplasmic reticulum, whereas the other source says that a small amount of calcium diffusing inwards is required to activate ryanodine receptor channels in the cardiac sarcoplasmic reticulum which then release large quantities of calcium which result in contraction. Regardless, what benefit do cardiac myocytes gain over skeletal muscles by being regulated by extracellular calcium? My best guess is that it helps prevent the possibility of tetany, but I am unsure.

  • $\begingroup$ It would be helpful to include specific links to the sources you refer to. You might also have more luck with the Medical Sciences Stack Exchange. medicalsciences.stackexchange.com $\endgroup$
    – ASimonis
    Mar 25, 2022 at 3:11


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