Skin 7, Sweating and thermoregulation

Functions of the skin


Protection
Protects deeper organs and acts as a barrier against invasion of microbes and other harmful agents.


Formation of vitamin D
Ultraviolet light from the sun converts 7- dehydrocholestrol a fatty substance contained in the skin into calcitrol. Vitamin D is used in the formation and maintenance of bone.


Waterproof
Prevents movement of fluids in and out of the body


Tactility, cutaneous sensation
Sensation of pain, touch, pressure and temperature and so protects the body.


Melanin production
Melanocytes produce the pigment melanin. Amount of pigment is determined by genetic inheritance and can be stimulated by sunlight.


Thermoregulation
Mainly by varying the vasotone of the blood vessels and the activity of the sweat glands.

These mechanisms either produce or conserve heat according to the need indicated by the heat regulating centre in the hypothalamus.

Vasodilation causes extra blood near the surface which increases heat loss by radiation, conduction and convection.

Vasoconstriction conserves heat.

The body is cooled by loss of the heat used to evaporate the water in sweat - when conservation of heat is required there is less sweat.


Excretion and absorption
400 mls of water transpiration