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.
