Page:Structure and functions of the body; a hand-book of anatomy and physiology for nurses and others desiring a practical knowledge of the subject (IA structurefunctio00fiskrich).pdf/45

 CHAPTER II.

THE SKIN, ITS APPENDAGES AND ITS FUNCTION.

—Vertical section of skin.

The whole exterior surface of the body is covered by the skin, an excreting and absorbing organ, which serves as a protection to the parts beneath and is also the organ of touch. It has two layers, a superficial and a deep. The superficial layer, the epidermis or cuticle, is composed wholly of epithelial cells, of which the deepest layer is columnar and moulded upon the papillary layer of the derma, while the intermediate layers are more rounded and the surface ones flat. The deepest layer also contains the skin pigment, which causes the variation in shade between the Indian, the negro, and the white man. Below the epidermis, which is chiefly protective, is the tough, elastic, and flexible tissue of the derma or true skin, in which are vested most of the activities of the skin. Its surface is covered with papillæ, which are more numerous in the more sensitive parts. Each papilla contains one or more capillary loops and one or more nerve fibers, while some terminate in an oval body known as a tactile corpuscle. Beneath the papillæ is the reticular layer, composed of interlacing bands of fibrous tissue and contain