What layer of skin serves as the primary barrier against environmental damage?

The stratum corneum is the outermost layer of the epidermis and serves as the primary barrier against environmental damage. Composed of dead, flattened skin cells that are eventually shed and replaced, this layer is key to preventing the entry of pathogens, chemicals, and other harmful substances. It also plays a vital role in minimizing water loss from the body, aiding in maintaining proper hydration levels.

The layered structure of the stratum corneum, with its tightly packed keratinized cells, provides mechanical protection, making it resilient against abrasion and injury. Additionally, the presence of lipids in this layer helps seal the skin, further enhancing its barrier function. Overall, the stratum corneum is fundamental to the skin's role as a protective shield for underlying tissues and organs against external threats.