Muscle oxygen level

Bronchiolar smooth muscle is sensitive to changes in carbon dioxide levels. Excess carbon dioxide causes bronchodilation and reduced carbon dioxide causes bronchoconstriction. Pulmonary vascular smooth muscle is sensitive to changes in oxygen levels excess oxygen causes vasodilation and insufficient oxygen (hypoxia) causes vasoconstriction. The changes in bronchiolar and vascular smooth muscle tone alter the amount of ventilation and perfusion in a lung unit to return the V/Q ratio to one. 

O Mahony F.C., O Riordan T.C., Papkovskaia N., Ogurtsov V.I., Kerry J.P., Papkovsky D.B., Assessment of oxygen levels in convenience-style muscle-based sous vide products through optical means and impact on shelf-life stability. Packaging Technol. Set, 2004 17 (4) 225-234. 

The expansion of the productivity of the biosphere by the eukaryotes must have begun slowly, but it probably started in late Archean. Around 2,300 Ma, much evidence suggests (but does not conclusively prove see Section 8.01.8.6) that oxygen levels rose sharply. Possibly the eukaryotes were beginning to muscle the world. 

There have been few studies on the effects of low oxygen levels on protein synthesis rates in fish. Muscle protein synthesis declined in Fundulus heteroclitus when the oxygen level fell (Jackim and LaRoche 1973). In contrast, the rates of liver protein synthesis of trout were similar in water at 100 or 50% air saturation (Fauconneau 1985). 

Hypoxia deprives the ETC of sufficient oxygen, decreasing the rate of ETC and ATP production. When ATP levels fell, glycolysis increases and, in the absence of oxygen, wiU produce lactate j (lactic acidosis). Anaerobic glycolysis is not able to meet the demand of most tissues for ATP, I especially in highly aerobic tissues like nerves and cardiac muscle. 

One aspect of exercise that increases the risk of heatstroke is that the loss of heat by sweating requires a proportion of the cardiac output to be directed away from muscle to the skin. In this way, heat is lost from the blood as it circulates close to the skin. However, even in severe hyperthermia, the blood supply delivering fuel and oxygen to the muscles takes preference over that to the skin. In this way, symptoms of hyperthermia are overriden and physical activity is maintained so that the core temperature can rapidly increase to dangerous levels. (Neilsen et al. 1990). 

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