Pennsylvania Esthetician State Board Practice Exam

Which type of cells primarily makes up the epidermis?

1. Melanocytes

2. Keratinocytes

3. Fibroblasts

4. Adipocytes

The correct answer is: Keratinocytes

The epidermis, the outermost layer of the skin, is primarily made up of keratinocytes. These cells are responsible for producing keratin, a key protein that provides structure, strength, and water-resistance to the skin. As keratinocytes move from the deeper layers of the epidermis to the surface, they undergo a process of keratinization, which helps to form a protective barrier against environmental factors such as pathogens and moisture loss. Melanocytes, while important for producing the pigment melanin which gives skin its color and protects against UV radiation, comprise only a small percentage of the cells in the epidermis. Fibroblasts are primarily found in the dermis rather than the epidermis and play a crucial role in producing collagen and elastin, which provide the skin with its structure and elasticity. Adipocytes, or fat cells, are found in the subcutaneous layer beneath the skin and are involved in fat storage and insulation, further distinguishing them from the primary cell type of the epidermis.