Which layer of skin acts as a barrier to protect underlying tissues?

The stratum corneum is the outermost layer of the epidermis and plays a crucial role as a protective barrier. It is composed of tightly packed, dead skin cells that have undergone a process called keratinization, where cells fill with keratin, a fibrous protein that provides strength and resilience.

This layer acts as the first line of defense against environmental factors such as pathogens, chemicals, and physical abrasions, effectively preventing them from penetrating deeper layers of the skin. Additionally, it helps to reduce water loss, maintaining hydration in the underlying tissues.

In contrast, the dermis lies beneath the epidermis and provides structural support and contains blood vessels, nerves, and connective tissue. The hypodermis, or subcutaneous layer, primarily serves to insulate, cushion, and connect the skin to underlying structures like muscles. The stratum spinosum, which is situated beneath the stratum corneum, plays a role in cell communication and immune function but does not serve as the primary protective barrier. Thus, the stratum corneum is specifically designed to act as a protective barrier for the skin.