What Is The Structure Of The Skin?

The outer portions of the skin (epidermis) consist of external horny layers of dry, dead cells, and a deeper growing layer, from which the outer layers are produced. As new cells are pushed outward, they lose their nuclei, flatten, develop thick walls, and eventually contain only dead materials. These are constantly being removed from the body surfaces by friction. Blood vessels do not enter the epidermis.

The growing layer also produces nails and hairs as outgrowth of the epidermis. The color of the skin is due in part to pigment deposits found in the growing layer and in part to the translucent nature of the skin which permits blood in the capillaries to show through. The amount of the different pigments determines the color of different races.

Beneath the epidermis lies the dermis, or true skin, a tough, fibrous, living tissue, embedded in it are the capillaries, lymph vessels, nerve endings, sense organs, sweat glands, sebaceous glands, and roots of hairs. The dermis is not flat on its outer surface but takes the form of tiny projections of papillae. These papillae are nutritive or sensory, depending upon whether they contain a capillary knot or a sensory nerve ending.

Below the dermis occurs a layer of subcutaneous tissue. This tissue serves as a storage place for reserve fat and acts as a cushion for the protection of the body. Its elasticity permits freedom in the movement of the skeletal framework that lie under the skin.

The skin is kept moist and soft by sebaceous glands which pour an oily substance 'sebum' into the hair follicle and by the seat glands which exude their liquid secretions directly on it surface.

The function of the skin may be summed up as protective, sensory and heat regulative.

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