Thermodynamic assessment of the entropy accumulation and exergy destruction in muscle and neuron cells

All living species can be treated as open systems that are in continuous exchange matter and energy to its subsystems and surroundings. The transduction of energy always obeys the laws of physics. Thermodynamic laws are great tools to demonstrate the significance of the feasibility of transduction of energy. The energy exchange for work done by biological systems is highly efficient. The energy production path starts with glycolysis in the cytoplasm of the cell while bulk production of energy is produced in mitochondria that are the "powerhouse" of the cells, where more than 90 percent of the cellular energy is produced. Functions of the body, like muscle work performance and signal transmission along the nervous system, are achieved by utilizing the energy generated in the mitochondria. The entropy and exergy thermodynamic terms provide an opportunity to interpret the efficiencies of biological systems and give the ability to compare calculated efficiencies with theoretical values. The thesis represents a comprehensive thermodynamic investigation on squid mantle muscles during different swimming behavior, the global warming effect of squid giant axon action potential cost and, pig cardiac muscles during basal metabolism and active state of the body. Thermodynamic analysis showed that during slow swimming, 3.82 J/(kg s) of chemical exergy was consumed, and a total muscle work of 0.28 J/(kg s) was produced while the jet escape consumes an exergy of 9.97 J/(kg s) and produces a muscle work of 0.16 J/(kg s). Thermodynamic analyses to determine the effects of the global warming on information transmittance in the giant squid neuron via Hodgkin and Huxley model showed that as temperature increases from 6.3 to 18.5 oC entropy generation was estimated to decrease by half, implying that living becomes easier for the squid as temperature increases. Thermodynamic analysis shows that a pig's heart consumed 0.63 J/kg s of exergy at rest and produced 0.033 J/kg s of muscle contraction work. In the active state, the heart consumed 1.31 J/kg s of exergy and produces 0.065 J/kg s of muscle work. The calculations of conversion of consumed chemical exergy into energy-rich compounds revealed that the active state of cardiac muscle is exergetically more efficient than that of the basal resting state.