An endothermic animal maintains an ideal body temperature by balancing heat losses and heat gains.
HEAT GAINS HEAT LOSSES
-Respiration – Evaporation
-Conduction – Excretion
-Convection – Conduction
– Radiation – Convection
– Heat is lost when water evaporates from the lungs and sweat evaporates from the skin.
– Convection: transfer of heat to and from the body on air currents. Can be increased by “fanning” air past the body.
– Radiation: transfer of heat in the form of rays, usually infra-red rays.
– Conduction: transfer of heat by direct contact with another object such as a cold rock or a hot oven door.
SKIN REDUCES HEAT LOSS BY :
Convection: contraction of hair erector muscles raises hairs and traps a layer of still air
Radiation: vasoconstriction of blood vessels leading to surface capillaries shunts blood away from skin
Evaporation: sweat glands do not secrete sweat.