The importance of a constant temperature

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.

 

 

 

 

 

 

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