BIO 203 Lecture Notes - Lecture 27: Ryanodine Receptor, Thermogenesis, Dihydropyridine
8 Dec 2017
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Homeothermy: body temperature of an endotherm remains constant. Spends time in shade as temperature rises. Returns to the constant temperature of its burrow at night. Bird ruffles feathers to expose its skin to absorb sunlight. At colder environmental temperatures, metabolic heat production increases in endotherms but falls in ectotherms. Metabolic rate of lizard is slower than a mouse. Within the thermoneutral zone, body temperature is regulated by passive mechanisms, such as heat loss through the skin. Below the lower critical temperature, the animal expends energy to produce metabolic heat. Above the upper critical temperature, the animal expends energy to lose heat by panting or sweating. Countercurrent flow to retain heat in body core. Homeoviscous membrane adaption to maintain membrane fluidity in colder extremities. Gills: thermal window for effective heat transfer: promotes poikilothermy. Countercurrent flow to retain heat in red muscle. Countercurrent flow to maintain regional temperature differences (maintain heat in trunk)
