Skin anatomy

Skin Anatomy

The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs.

Structure

Skin is made up of three layers: the epidermis, the dermis, and the hypodermis.

Epidermis

The epidermis is the outermost layer of the skin. It forms the body's major barrier against an inhospitable environment. It is a stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes.

Dermis

The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis provides tensile strength and elasticity to the skin through an extracellular matrix composed of collagen fibrils, microfibrils, and elastic fibers, embedded in hyaluronan and proteoglycans.

Hypodermis

The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves.

Functions

Skin performs the following functions: Protection, Regulation, and Sensation. It acts as a barrier, regulates body temperature, and permits the sensations of touch, heat, and cold.

Clinical significance

Skin plays an important role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates.

See also

• Dermatology
• Skin disease
• Skin care