haut

Haut, in German, means skin, the outer covering of the body and the largest organ of the integumentary system in humans and many animals. It serves as a physical barrier, regulates temperature, allows sensation, and participates in immune defense and vitamin D synthesis.

The skin comprises three principal layers: the epidermis, the dermis, and the subcutaneous tissue. The epidermis is a stratified squamous epithelium mainly formed by keratinocytes that proliferate in the basal layer and move outward; it also contains pigment-producing melanocytes and immune cells such as Langerhans cells. The dermis lies beneath the epidermis and consists of connective tissue with collagen and elastin fibers, blood vessels, nerves, hair follicles, and glands (sweat and sebaceous). The subcutaneous tissue, or hypodermis, anchors the skin to deeper tissues and stores fat, providing insulation and cushioning.

Functions of the skin include protection against mechanical injury, pathogens, and desiccation; thermoregulation through sweat production and blood vessel regulation; sensation via a network of nerve endings that detect touch, pressure, temperature, and pain; and participation in immune surveillance and vitamin D synthesis in response to UV exposure. Skin pigmentation, mainly determined by melanin, influences color and offers some protection against ultraviolet radiation.

Common conditions affecting the Haut include dermatitis, psoriasis, infections, acne, and various forms of skin cancer. Aging can lead to thinning, reduced elasticity, and slower wound healing. Proper care, sun protection, hygiene, and moisturization contribute to skin health.