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Homo Sapiens (“Us”): Strengths and Weaknesses
Published in Michael Hehenberger, Zhi Xia, Huanming Yang, Our Animal Connection, 2020
Michael Hehenberger, Zhi Xia, Huanming Yang
The physiology of human muscles is also worth a brief discussion, in view of what we have learned about ATP in a previous chapter: our body produces the majority of its ATP aerobically in the mitochondria without producing lactic acid or other byproducts causing fatigue or pain. When exercising our muscles, a second “nonstandard” method of ATP production can come into play. During activity that is higher in intensity, ATP production can switch to another (but less efficient) pathway, referred to as “anaerobic glycolysis.” Anaerobic ATP production may have occurred during the early days of life on Earth, when there was no oxygen in the atmosphere. It produces ATP and allows near-maximal intensity exercise, but also produces significant amounts of lactic acid which limit the sustainability of such high intensity exercise to only a few minutes.
Mathematical modeling of the cardiac tissue
Published in Mechanics of Advanced Materials and Structures, 2022
A number of models of the chemical kinetics of muscle contraction are known from the literature (see Reviews in Long [87], Long and McIntire [88, 89], Huxley [99], Zozulya et al. [43], etc.). In all models, the fundamental features of muscle biochemistry are clearly presented. The energy supplier for mechanical muscle contraction is ATP hydrolysis. Under aerobic and anaerobic conditions in the muscular system, exchange occurs only between Ca2+, ions, actomyosin and total phosphate. The concentration of ATP remains almost constant under normal physiological conditions of muscle function. In addition, on the basis of known physiological facts and chemical simplifications, a number of assumptions are introduced that do not affect the quality of modeling. It is assumed that no attractive diffusion mechanism is required to bring energy to a point; chemical energy is stored in any elementary volume of tissue. This hypothesis of continualization is traditionally used in rigid body mechanics, and in this case it has a physiological interpretation. When oxygen is not available, muscles act by anaerobic glycolysis. When glycolysis is blocked, functioning occurs due to the transphosphate transition of phosphocreatine to ATP.