Thermoregulation (Will)

What is Thermoregulation?

Thermoregulation is the regulation of internal temperature by negative feedback mechanisms. This means that the body will sense changes in internal or external temperature, and then trigger different behavioral and physiological responses that work to maintain a set internal temperature. (E.G. rate of metabolism)

Mechanisms of Thermoregulation

Conduction - direct contact
Convection - within a fluid (liquid or gas)
Radiation - elctromagnetic radiation
Evaporation - water absorbs energy and evaporates

All these mechanisms are usually working simultaneously.

Conduction

The flow of thermal energy between molecules in direct contact. Animals will lose heat when in contact with something cooler, gain heat when in contact with something warmer.

Convection

The transfer of thermal energy within a fluid (liquid or gas). Animals will gain heat when in contact with a warmer fluid, lose heat when in contact with a cooler fluid.

Radiation

The transfer of thermal energy in the form of electromagnetic radiation. Animals always lose energy through radiation, more when it is warmer. Energy is also gained through radiation from the Sun.

Evaporation

Aids the transfer of thermal energy. (e.g. sweat). Water on the surface of the skin evaporates, thus absorbing thermal energy from the skin and cooling it.

Homeotherms and Poikilotherms

A homeotherm is an organism that is able to maintain a stable and constant body temperature, regardless of its external environments temperature. Birds and mammals are homeotherms, and they maintain a body temperature that is often higher than the external temperature of their environment.

A poikilotherm is an organism whose internal body temperature varies, and often matches the external environments temperature. Fish and reptiles are examples of poikilotherms.

Ectotherms

An ectotherm is an animal that maintains its body temperature through the absorption of thermal energy from the environment. All ectotherms generate some some thermal energy through internal reactions. An ectotherms metabolic rate typically falls as the temperature falls in order to conserve energy (see graph below). They are less active during during cooler weather, and when the temperature falls low enough, they become inactive. This makes them vulnerable to predators. However, they are not actively looking for food, so they are less likely to be exposed to predators.

Endotherms

An endotherm is an animal that maintains its internal temperature through its internal reactions and mechanisms. They are typically more successful at maintaining their internal temperature than ectotherms. An endotherms metabolic rate typically rises as the temperature drops (see graph above). They keep their bodies at an optimal temperature by regulating how much thermal energy is exchanged with the environment. This means that the temperature does not affect their activity, but it does require a constant supply of energy.

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