Knowra Skin barrier Skin barrier The skin barrier is the outer skin’s physical and chemical defenses, which limit water loss and impede the entry of irritants, allergens, and microbes.
Stratum corneum : The outermost epidermal layer, composed of dead cells embedded in lipid-rich material. Its cells and surrounding lipids form the barrier’s main physical seal.
Epidermis : The outermost layer of skin, forming a protective interface between the body and its environment. The barrier is concentrated in the epidermis, especially its outermost layers.
Atopic dermatitis : A chronic inflammatory skin disease characterized by itchy, relapsing eczema. Barrier impairment and inflammation reinforce one another in this disease.
Cutaneous immune system : The network of immune cells and signals that detects and responds to threats in the skin. Immune responses act alongside the barrier but are not the same as its physical seal.
Epidermal lipids : Lipids in the epidermis, including ceramides, cholesterol, and free fatty acids. Their organized layers between corneocytes restrict water loss and substance entry.
Keratinocyte : The predominant cell type in the epidermis, producing keratin and contributing to skin defense. Keratinocytes build the barrier and release signals that coordinate its defenses.
Irritant contact dermatitis : Skin inflammation caused by direct damage from chemical, physical, or environmental exposures. Irritants provoke inflammation when they damage or overwhelm the barrier.
Skin microbiome : The community of microorganisms that inhabit the skin’s surface and associated niches. Resident microbes can support defense, while the barrier itself limits entry.
Natural moisturizing factor : A mixture of small, water-attracting molecules inside corneocytes that helps maintain skin hydration. It keeps the barrier’s outer cells hydrated and flexible.
Corneocyte : A flattened, dead cell in the stratum corneum, enclosed by a tough protein envelope. Corneocytes act as the barrier’s structural bricks.
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