Certified Wound Ostomy Nurse (CWON) Practice Test

What is the outermost layer of the skin?

1. Epidermis

2. Dermis

3. Subcutaneous Tissue

4. Basement Membrane Zone

The correct answer is: Epidermis

The outermost layer of the skin is the epidermis. It serves as the primary barrier protecting the body from external factors such as pathogens, chemicals, and physical injuries. The epidermis is composed mainly of keratinocytes, which produce keratin, a protein that enhances the skin's protective qualities. Additionally, the epidermis contains melanocytes, which produce melanin for skin pigmentation, and Langerhans cells, which have a role in immune responses. Understanding the function and structure of the epidermis is crucial for wound care and ostomy nursing, as it directly impacts the healing processes and the skin's overall health. The other layers mentioned—dermis and subcutaneous tissue—lie beneath the epidermis and contribute to the skin's structure and functions, but they are not the outermost layer. The basement membrane zone serves as a boundary between the epidermis and dermis but is not an actual layer of skin visible from the exterior.