Knowra Human skin Human skin Human skin is the body's outer covering and largest organ. Its layers protect against injury, pathogens, and water loss while supporting sensation and temperature regulation.
Epidermis : The outermost layer of skin, made chiefly of keratinocytes and lacking blood vessels. Its renewing surface cells form the first barrier against water loss and environmental exposure.
Stratum corneum : The outermost epidermal layer, composed of flattened dead cells embedded in lipid-rich material. Its cells and lipids create the main barrier to water escape and external substances.
Dermatology : The medical specialty concerned with skin, hair, nails, and disorders affecting them. It diagnoses and treats conditions involving the body's outer organ.
Mucous membrane : A moist tissue lining body cavities and passages that open to the exterior. Unlike external skin, it protects internal surfaces and is kept moist.
Skin microbiome : The community of microorganisms that inhabit the skin and interact with its environment and immune system. Its effects on barrier health and disease remain an active research area.
Dermis : The connective-tissue layer beneath the epidermis, containing blood vessels, nerves, glands, and hair follicles. Its vessels and sensory structures support many functions absent from the epidermis.
Eccrine sweat gland : A coiled skin gland that releases watery sweat onto the surface through a duct. Evaporation of its sweat cools the body during heat stress.
Skin cancer : A group of cancers arising from skin cells, including basal cell carcinoma, squamous cell carcinoma, and melanoma. Ultraviolet exposure and changes in skin cells make these cancers a major concern.
Callus : A localized thickening of the outer skin layer caused by repeated pressure or friction. It shows how skin can reinforce a frequently stressed surface.
Atopic dermatitis : A chronic inflammatory skin disease marked by itch and impaired barrier function. It exposes unresolved links among barrier defects, immunity, and microbial communities.
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