Thermoregulation

Homeostasis and Thermoreceptors.

Homeostasis refers to keeping the body in a steady state or equilibrium (in terms of body temperature, the optimum operating temperature is 36-37.5 degrees.) Temperature homeostasis is called thermoregulation and is controlled in the thermoregulatory center in the hypothalamus. It receives input from two sets of thermoreceptors, which are specialized receptors found in the skin that detect changes in temperature.

Receptors in the hypothalamus regulate the temperature of the blood itself as it passes through the brain (core temperature) and the thermoreceptors in the skin around the body monitor the external temperature. Both sets of information are needed.

Thermoregulation

Thermoregulation refers to the body’s efforts to maintain the optimal temperature of around 37 degrees. It involves the body’s ability to both dissipate and gain heat depending on the situation. It does it in four ways; radiation, evaporation, conduction, and convection. Shivering is a protective mechanism designed to generate heat from muscle activity.

Radiation

Energy transferred when heat passes from blood vessels to the skin and across the air space above the skin.

Evaporation

The conversion of a liquid into a gas, evaporation of sweat is the most common example of this method.

Conduction

The transfer of thermal energy between two solids in contact with each other.

Convection

When heat is transferred by the circulation of a fluid or gas (pouring water on yourself/standing in front of a fan)

Hyperthermia and Hypothermia

Both are conditions that occur when body mechanisms are overwhelmed via extreme temperatures. Hyperthermia occurs when the body gains more heat than it can lose.

Hypothermia occurs when the core temperature falls below the required to maintain minimum metabolic functions.

Sweating

The main method the body uses to cool itself. Warm blood is shunted to the skin via vasodilation (less oxygen to muscles because of this). At the skin, sweat glands secrete water to be evaporated, to evaporate properly, the sweat absorbs energy from the skin. This causes blood in the capillaries of the skin to cool, this cooled blood is then sent back to other parts of the body, where it can pick up heat and repeat the cycle.

Dehydration causes surface blood vessels to constrict, effectively stopping sweat production in an attempt to preserve blood volume. This loss of a thermoregulatory method leads to a dramatic increase in core temperature.