Exercise and Thermoregulation Flashcards

Flashcards covering the mechanisms of thermoregulation, heat transfer, and physiological responses to exercise in heat and cold environments.

Homeothermic

The ability of humans to maintain a constant body temperature, typically within a normal range of $36.1-37.8\,^{\circ}C$.

Hypothalamus

The location of the thermoregulatory center in the human brain that maintains a constant body temperature.

Conduction

The transfer of heat by direct molecular contact, such as from the body core to adjacent tissues or from the body surface to clothes, air, or water.

Convection

The transfer of heat by the motion of a gas or liquid across a heated surface, such as air or water molecules moving over the skin.

Radiation

The primary source of heat loss at rest (approximately $60\%$) where body heat is given off via infrared rays.

Evaporation

The major cooling mechanism during physical activity where liquid sweat is converted to vapor by heat from the skin, accounting for $80\%$ of heat loss during exercise.

Humidity

An environmental factor that, when high, prevents sweat evaporation and makes exercise extremely hard on the body.

Heat Transfer in Water

A process where conduction is several thousand times greater than in air, leading to rapid heat loss.

Sweat Rate

A variable dependent on environmental conditions, exercise intensity, fitness level, acclimatization, and hydration; it may exceed $1\,L/hr$ during exercise.

Plasma Volume

A component of blood that decreases if fluids are not replaced during exercise, leading to cardiovascular implications.

Shivering

A muscle activity mechanism used during cold stress to increase the body's heat production.

Cold Stress Peripheral Blood Flow

A physiological response to the cold where blood flow to the periphery decreases while blood flow to the core increases.

Child Thermoregulation in Cold

A condition where children have more difficulty maintaining heat due to a larger body surface to mass ratio.

Cold Acclimatization

An adaptation process with less capacity than heat exposure, characterized by a lower threshold body temperature for shivering and increased blood flow to extremities.

CV Drift

A phenomenon during exercise in the heat where Cardiac Output ($Q$) is maintained by increasing heart rate to compensate for decreased stroke volume (SV).

LVEDV (Left Ventricular End-Diastolic Volume)

A cardiovascular measure that decreases during exercise in the heat due to reduced venous return.

Metabolic Effects of Heat Exercise

Includes increased $O_2$ consumption, higher sweat production, increased respiration, and an increased rate of glycogen depletion and lactate accumulation.