derma

Derma, from the Greek derma meaning skin, is a term used in biology and medicine to refer to the skin as an organ in humans and other animals. In medical language, derma appears in terms such as dermatology and dermal. The skin consists of several layers and serves as a protective barrier, a sensory organ, and a regulator of temperature and hydration. The three anatomical layers are the epidermis, dermis, and hypodermis (subcutaneous tissue).

The epidermis is the outer layer, mainly keratinocytes, with a stratified structure including the stratum corneum. The dermis lies beneath the epidermis and is the true skin; it contains dense connective tissue, collagen and elastin fibers, blood vessels, nerve endings, hair follicles, sweat and sebaceous glands. The subcutaneous layer houses fat and larger blood vessels and helps insulate the body.

Functions of the skin include protection against pathogens, prevention of water loss, and participation in immune defense and sensation. The epidermis hosts immune cells such as Langerhans cells, while the dermis provides a rich network of nerves and blood vessels. The skin also plays a role in thermoregulation through sweat secretion and vascular changes, and it synthesizes vitamin D precursors in response to sunlight.

Clinical relevance: Dermatology is the medical specialty focused on skin disorders, including dermatitis, eczema, psoriasis, acne, and skin cancer such as melanoma. The term derma appears in cosmetic sciences and dermatopathology, and the dermal layer is a target in cosmetic procedures and transdermal drug delivery.