BIO 2110 Lecture Notes - Rete Mirabile, Water Conservation, Wind Chill
Document Summary
Life in the hot zone reduce heat production increase heat loss. Many animals are perfectly adapted to cold. Well insulated by fur or feathers (air) subcutaneous fat (water) large animals have short extremities reserves of body fat. Penguins feet not insulated but always a few degrees above zero. Feet are one of the few regions of heat exchange. Fat is not sufficient to maintain tb we huddle. How cold the lowest ta humans can tolerate is determined by duration and extent of exposure (no clear limit) human can withstand considerable cold as long as they are: well wrapped, well nourished, good shelter. Wind chill factor: makes us feel colder, because air is a fluid and as it moves it replaces air around us making us cold. Regional heterothermy in endotherms used to prevent heat loss allow extremities to cool (tlimb < tc) cold returning blood. We can have heat exchange because of counter current exchange of heat.
