Arkansas Esthetician Practice Exam

The epidermis is primarily composed of which cells?

1. Melanocytes

2. Keratinocytes

3. Langerhans cells

4. Fibroblasts

The correct answer is: Keratinocytes

The epidermis is primarily composed of keratinocytes, which are the predominant cell type found in this outermost layer of skin. These cells originate from the basal layer and play a crucial role in forming a protective barrier. As keratinocytes move up through the layers of the epidermis, they undergo a process of keratinization, where they fill with the protein keratin and eventually die, contributing to the skin's protective function. While melanocytes, Langerhans cells, and fibroblasts are also important for skin health, they serve different functions. Melanocytes are responsible for producing melanin, the pigment that gives skin its color, which is vital for protection against UV radiation. Langerhans cells play a role in immune response within the skin, alerting the body to foreign invaders. Fibroblasts, on the other hand, are located primarily in the dermis, not the epidermis, and are essential for producing collagen and elastin, contributing to the skin's structure and elasticity. Thus, the choice of keratinocytes as the primary building blocks of the epidermis is correct due to their abundance and critical function in skin barrier protection.