ANT203H5 Lecture Notes - Lecture 14: Coping With, Epas1, Hemoglobin
Document Summary
In this lecture we will review three examples of how humans respond physiologically and morphologically to environmental challenges. Humans, as most other mammals, have very efficient systems to regulate internal body temperature: optimal temperature is around 37. It is dangerous for the internal body temperature to be higher than 40 (hyperthermia), and if below 35 (hypothermia) Let"s review some physiological responses to cold and heat stress. Vasoconstriction: narrowing of blood vessels to reduce blood flow and heat loss: tissue and organ damage. Vasodilation: opening of blood vessels to increase blood flow and heat loss. Lewis hunting phenomenon: after initial exposure to cold stress, there are alternating cycles of vasoconstriction and vasodilation. After some time the cycles become more frequent and less extreme, maximizing the efficiency of the process. First you have more dramatic cycles, that eventually stabilize and become less extreme: this is a way in which the efficiency maximizing.
