BIOL 1210 Lecture 25: heat in cellular physiology
Document Summary
Heat inside cell from chemical reactions (heat lost in reaction, never full conversion) Larger cell makes more heat per surface area (because volume is larger than surface area) Too low- moves too slow or frozen. The relationship between temperature and chemical reactions. Different enzymes have different thermal optima (and organisms) Ectothermic: unable to use metabolically generated heat to be warmer than the surrounding environment. Endothermic: can use metabolically generated heat to increase body temperature. Poikilothermic: fluctuations in body heat (reptiles, insects, etc. ) : can"t function if under attack or needed in action, not always at thermal optima. : uses less energy to function only when needed. Nonshivering thermogenesis: uses etc in mitochondria, but it short- circuits the flow thru atp synthase to have the h+ generate heat. Demand side: (reduce the rate of loss) Homeothermic: maintain body temperature close to their thermal optima at all times (mammals, birds) : can always function when needed in action.
