keratinizaci

Keratinization is a biological process by which cells, primarily epidermal cells, synthesize and accumulate keratin. Keratin is a tough, fibrous protein that forms the structural component of the outer layers of skin, hair, and nails. This process is crucial for providing a protective barrier against environmental damage, pathogens, and water loss. In the skin, keratinization begins in the basal layer of the epidermis and involves a series of differentiation steps as cells migrate towards the surface. As they move outward, they lose their nuclei and organelles, becoming flattened and filled with keratin. This creates the stratum corneum, the outermost layer of the epidermis, which is composed of dead, keratinized cells called corneocytes. These corneocytes are cemented together by lipids, forming a robust and impermeable barrier. The rate of keratinization can be influenced by various factors, including hormonal signals, vitamin A, and mechanical stress. Disorders affecting keratinization can lead to conditions like ichthyosis, where skin shedding is abnormal, or hyperkeratosis, characterized by excessive thickening of the stratum corneum.