THERMAL PHYSIOLOGY

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THERMAL PHYSIOLOGY

Heat production may happen as a by-product of metabolic processes.

Thermogenesis

An endothermic organism struggles in face of a colder-than-desirable ambient.

Thermal energy will not be transferred when there is thermal equilibrium.

The inefficient part of molecular transformations that causes part of the energy not to be used for work, but instead, lost as heat.

Thermoregulation

Physiological response

Countercurrent Exchange

Circulating Adaptation

Vasocontriction

Vasolidation

Non-shivering

Metabolism --> increase heat production.

Shivering

Muscle contraction --> increase heat production.

Sweating

Insulation

Behavioral response

Surface area/ volume

Thermal strategies

Homeotherm

Maintain relatively constant internal environmental.

Poikilotherm

Body temperature varies directly with environmental temperature.

Endotherm

Rely heavily on metabolic energy.

Ectotherm

Rely mainly on external energy source.

To investigate the biological implications of temperature to the function of living organisms.

Thermal zone

Thermoneutral zone

Metabolic rate is minimal (basal metabolic rate).

Lower critical zone

Metabolic rate ↑ to induced heat production. (Hyphothermia)

Upper critical zone

Metabolic rate ↑ to induced a physiological response to prevent overheating. (Hyperthermia)

Heat fluxes (Body Temperature, TB)

Evaporation

Magnitude of heat loss depend on volume of H2O and its heat of vaporization.

Water molecules absorb thermal energy from an object when making the transition from liquid to vapor.

Radiation

All bodies, including mammals, emit heat by radiation.

Transfer of thermal energy in the form of light waves, as exemplified by the heat we receive from the sun.

Convection

Exchanged depend on: • thermal gradient • rate of flow the fluid • the conductivity of the fluid

The heat is being carried from one point to another by a moving substance.

Conduction

Rate depend on: • area of physical contact • different temperature • thermal conductive properties

Heat flows from a region of ↑ temperature to a region of lower temperature.

Direct transfer of heat between two substances in contact with each other.

Metabolism

Main source of thermal energy in the heat balance equation.

This includes adaptations in face of environmental challenges.