Which skin layer consists of keratin, a protein?

The epidermis is the outermost layer of the skin and is primarily composed of keratinocytes, which produce keratin, a resilient protein that protects the skin and helps to waterproof it. This layer plays a crucial role in shielding the underlying tissues from environmental damage, pathogens, and dehydration. Keratinization, the process by which keratinocytes produce keratin, is vital for maintaining skin integrity and function, making the epidermis essential for overall skin health.

The dermis, while important, is primarily made up of connective tissue and does not consist of keratin. The hypodermis, or subcutaneous layer, lies beneath the dermis and is composed mainly of fat and connective tissue; it serves as insulation and cushioning for the body. Both of these layers, though critical to skin anatomy, do not contain keratin in the way the epidermis does. Hence, the epidermis is the correct choice when identifying the skin layer characterized by the presence of keratin.