In the skin, what is the outermost layer called?

The outermost layer of the skin is known as the epidermis. This layer serves as a protective barrier, preventing pathogens and harmful substances from entering the body while also minimizing water loss. The epidermis is composed mainly of keratinocytes, which produce keratin, a protein that helps in waterproofing the skin and protecting it from mechanical damage. This characteristic is crucial for maintaining skin health and function.

The dermis, found beneath the epidermis, contains connective tissue, hair follicles, and other structures but is not the outermost layer. The subcutaneous layer, or hypodermis, lies beneath the dermis and consists mainly of fat and connective tissues that insulate the body and support the skin, but it is also not considered part of the skin's outermost layer. Therefore, the correct identification of the epidermis as the outermost layer reflects its critical role in skin protection and physiology.