Final answer:
The epidermis is the outer layer of the skin that protects the body and has functions such as protection and water retention. The normal healing time for the epidermis is about 4 weeks.
Step-by-step explanation:
The epidermis is the outer layer of the skin that consists mainly of epithelial cells. It is the most superficial layer of the skin, forming a protective barrier over the body's surface. The epidermis has several important functions, including protection against physical damage, pathogens, and UV light, water retention, and synthesis of vitamin D.
The normal healing time for the epidermis is about 4 weeks. During this time, the entire layer is replaced as cells in the stratum corneum, the most superficial layer of the epidermis, are shed and replaced by cells pushed up from the lower layers.