BIOL 221 Lecture Notes - Lecture 9: Skeletal Muscle, Thyroid Hormones, Vasoconstriction
3 Mar 2020
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Document Summary
Heat is constantly exchanged with the environment. Heat may be lost or gained by radiation. For example, we gain heat from solar radiation but lose heat to the environment through our own infrared radiation. Heat may be gained or lost by conduction; for example, touching a warm radiator would cause a person to gain heat while touching a cold cement bench would cause heat loss. Of course, if the bench has been warmed by the sun, heat may be gained. Heat is lost as warm air is moved away by air flowing over the body. The warmer the air, the less heat is lost; the colder the air, the more heat is lost. Heat is also lost through evaporation of water on the skin as body heat transforms liquid water into water vapor. This forms the basis of cooling by sweat. Heat is produced by cellular metabolism due to basal activity in the internal organs (e. g. , brain, heart, kidneys).
