Keratinizáció

Keratinizáció is the process by which epidermal cells (keratinocytes) are produced and mature, eventually forming a protective layer. This process begins in the basal layer of the epidermis, where new cells are constantly generated through cell division. As these new cells move upwards towards the skin's surface, they undergo a series of changes. They accumulate keratin, a tough, fibrous protein that gives the epidermis its structural integrity and makes it waterproof.

During keratinization, the cells flatten, their nuclei and organelles disappear, and they become filled with keratin. This transformation is a key aspect of differentiation, where cells specialize for a particular function. The uppermost layer of the epidermis, the stratum corneum, consists entirely of dead, flattened keratinocytes, also known as corneocytes. These cells are arranged like shingles and are continuously shed and replaced by new cells migrating from below.

This protective barrier formed by keratinization is crucial for the skin's function. It prevents water loss, protects against mechanical injury, and acts as a barrier against the invasion of pathogens. The rate of keratinization can be influenced by various factors, including hormones, friction, and certain medical conditions. For example, conditions like psoriasis involve an accelerated rate of keratinization, leading to the characteristic thick, scaly patches.