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February 26, 2010

Regulation Of Body Temperature

The skin plays an important role in the regulation of body temperature and protecting it from sudden temperature changes. Our body needs to be kept at an optimum operating temperature in order for our cells to perform properly. Temperature affects the rate of chemical reactions inside the body. The average body temperature is 98.6F or 37 degree centigrade. The body temperature is kept constant by physiological adjustments controlled by the hypothalamus which acts as a thermostat. The hypothalamus receives nerve impulses from the heat and cold thermoreceptors in the skin called the peripheral thermoreceptors as well as from central thermoreceptors located in the hypothalamus itself.

Our body uses energy to generate heat through the vital actions of the body. This heat production rises with muscle activity like exercise and shivering. Heat is lost and gained through radiation, conduction and conviction while evaporation contributes only to heat loss which occurs through sweating.

When someone has a fever the body thermostat will be set at a higher level, therefore the person first shivers leading to heat release which will lead to the rise of temperature to the new setting, and when the fever subsides the setting of the thermostat will drop back to normal and the person sweats to dispose the excess heat.

In cold weather the cold receptors on the skin will be stimulated sending signals to the hypothalamus and the higher cortical centers. The hypothalamus is also activated by the change in the blood temperature; the response will be constriction of the blood vessels in the skin preventing too much blood from the entering the skin and keeping it inside the body so that little heat is lost, there will be decreased sweating, contraction of the muscle attached to the hair follicle which is called arrector pili muscle and this will lead to pulling the hair up which traps air close to the skin. Shivering is contraction of skeletal muscles leading to release of heat. The skin also acts as an insulation layer through the adipose tissue of the hypodermis which prevents heat loss.

In hot weather the heat receptors will be stimulated sending signals to the hypothalamus and the higher cortical centers and the response will be dilatation of the blood vessels in the skin leading the blood to run near the surface of the skin and this will allow heat to escape from the blood. There will be increased sweating. For sweat to evaporate it needs heat which is taken from our body and that's why we feel cooler when we sweat.

It's important in hot weather to drink enough fluids to avoid dehydration. It's also important to protect ourselves from excessive sun exposure and use protective measures such as sunscreens and protective clothing. (See sunburn part I, II)

This information is not intended nor implied to be a substitute for professional medical advice; it should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. Call 911 for all medical emergencies.