Monday, April 23, 2012

The Human Skin

        

Skin is the outer layer of our body. It is the largest organ of the body. It performs many necessary functions. Besides protecting internal organs from injury and preventing infection, skin relates the sense of touch and plays an important role in excretion and temperature regulation also. Skin makes vitamin D. an important function of the skin is to control the loss of the body fluids. It also excretes body wastes in the form of sweat.
                                
Structure of Skin

Epidermis: This is the outer layer of the skin. Much of this layer is made up of dead, flattened, horny cells. These cells are constantly being worn away and replaced by new cells from underneath. It does not contain blood vessels.

Dermis: Next to the epidermis is dermis. It contains blood vessels together with sweat and sebaceous glands, fat cells and nerve endings that form receptors for the sense of touch, heat, cold, pressure and pain. The outer surface of the dermises covered with a pattern of tiny elevations called papillae. The amount of blood flowing through the blood vessels of the dermis is controlled automatically by the nervous system. Blood circulation and sweat control the body temperature.

Sebaceous glands: these glands produce sebum which keeps the hair root lubricated.

Subcutaneous fat: it protects the skin.

Erector muscle: this keeps the hair erect.

Blood vessel: these blood vessels take oxygen through skin.

Sweat glands: these glands produce sweat to control the body temperature and excrete waste materials from the body.

Malphigian layer: It produces a pigment called melanin. This pigment is responsible for the color of the skin.
          The thickness of the human skin varies from about 0.05mm to 0.65cm. skin is the thinnest on the eyelids and the thickest on the sole of the feet.

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