Brief Look at the Skin

Skin is the largest organ of the body. It is composed of two major layers: the epidermis, which is the outer layer; and the dermis, which is beneath the epidermis. The skin protects the body from the environment, aids in controlling the body's temperature, and prevents the body's fluid loss.

The epidermis has four layers: the basal layer (stratum germinativum), which is the deepest layer covering the dermis, the spinous layer (stratus spinosum); the outer layer; and the cornified layer (stratum corneum).

Epidermal cells migrate from the basal layer to the surface of the skin where cells die. Their cytoplasm is converted to keratin, which is the hard, rough texture that forms keratinocytes. Eventually keratinocytes slough off and new layers of epidermal cells migrate upward.

The dermis has two layers: the papillary layer, which is next to the epidermis; and the reticular layer, which is the deeper layer of the dermis. Dermal layers are comprised of fibroblasts, collagen fibers, and elastic fibers. Collagen and elastic fibers give the skin strength and elasticity. The dermal layer contains sweat glands, hair follicles, sebaceous glands, blood vessels, and sensory nerve terminals.

Subcutaneous tissue lies under the dermis and supports and protects the dermis. Subcutaneous tissue consists of fatty tissue, blood and lymphatic vessels, nerve fibers, and elastic fibers.

0 0

Post a comment