EXPH 2115 Key Terms -- Lecture 11: Thermoregulation

thermoregulation

control of core body temperature via heating and cooling mechanisms

homeotherm

animal that maintains constant core body temperature by virtue of its own heating and cooling mechanisms

Core Body Temperature (T_c)

temperature of metabolically active/critical organs (e.g. brain, heart)

Skin (shell) Temperature (T_sk)

variable temperature due to the environment of which a small % of the thermoregulatory response is based

heat balance equation

thermal equilibrium between heat added to and removed from a system

metabolic heat

heat liberated during metabolic reactions, scales with exercise intensity, reliable source of heat gain

radiation

heat transfer of thermal energy by means of electromagnetic (infrared) waves

conduction

heat transfer between molecules in direct contact with each other

convection

heat transfer to or away from molecules via a fluid (liquid or gas), can be natural or forced (e.g. via fan)

evaporation

heat loss mechanism involving conversion a liquid to vapor, requires ~580 kcal of heat/L of water

humidity

concentration of water vapor in air, inhibits evaporation thus threatens temperature regulation in the heat

thermoneutral zone

ambient temperature range in which a nude individual need only use vasomotor tone to regulate

vasomotor control

blood vessel tone regulation, involves varying sympathetic adrenergic receptors

sudomotor control

regulation of swear gland activity, involves varying sympathetic cholinergic receptors

dehydration

excessive water loss from the body, often expressed as a % of body weight lost

dysthermia

poor temperature regulation

hyperthermia

elevated core body temperature

heat exhaustion

heat illness stage due to excessive heat, sweating, dehydration, and competition for blood (T_c ~ 99-102 F)

heat stroke

most severe (life-threatening) heat illness stage in which thermoregulation is impaired (T_c can be > 106 F)

hypothermia

low core body temperature

central blood volume

blood within the major vessels of the thorax, lower in hot conditions with blood in vasodilated skin

acclimation

process of getting accustomed to a new condition via adaptations