Arizona Esthetics State Board Practice Exam

What is the primary cellular component of the epidermis?

1. Melanocytes

2. Keratocytes

3. Fibroblasts

4. Dermal papillae

The correct answer is: Keratocytes

The primary cellular component of the epidermis is keratinocytes. These cells are crucial for the formation of the epidermal layer, which acts as the outer protective barrier of the skin. Keratinocytes produce keratin, a fibrous protein that helps waterproof the skin and provides strength and resilience against mechanical stress and environmental factors. Keratocytes originate from the basal layer of the epidermis, where cell division occurs. As they mature, they move upwards through the layers of the epidermis, undergoing a process called keratinization. During this process, they eventually flatten and lose their nuclei, ultimately forming the stratum corneum, which consists of dead, keratin-rich cells that continuously shed and are replaced. Other cell types, such as melanocytes, are also present in the epidermis but serve different functions. Melanocytes are primarily responsible for producing melanin, the pigment that contributes to skin color and provides some protection against UV radiation. Fibroblasts, although important in the dermis for producing collagen and elastin, are not found in the epidermis. Dermal papillae are structures that arise from the dermis, assisting in anchoring the epidermis and providing nutrients but are not cellular components of the epidermis itself