The Skin - Structure of the skin

The skin is made up of two layers. The outer later, or epidermis , has a surface of horny, nonliving cells that form the body's protective envelope. These cells are constantly being shed and replaced by new ones, which are made in the lower or inner layer of the epidermis.

Underneath the epidermis is the dermis , the thicker part of the skin. It contains blood vessels, nerves, and connective tissue. The sweat glands are located in the dermis, and they collect fluid containing water, salt, and waste products from the blood. This fluid is sent through tiny canals that end in pores on the skin's surface.

The oil, or sebaceous , glands that secrete the oil that lubricates the surface of the skin and hair are also located in the dermis. They are most often associated with hair follicles . Hair follicles and oil glands are found over most of the body, with the exception of the palms of the hands and the soles of the feet.

The layer of fatty tissue below the dermis, called subcutaneous tissue, acts as an insulator against heat and cold and as a shock absorber against injury.

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