The outermost and thinnest layer of the skin is called

• A. Epidermis
• B. Dermis
• C. Hypodermis
• D. Subcutaneous

Answer: (A)

The thing being tested is knowing which skin layer sits on the very outside. The outermost surface of the skin is the epidermis, a thin, protective barrier built mainly from keratinocytes that produce keratin and help waterproof the skin. It sits above the dermis, which is thicker and provides strength, nourishment, and houses blood vessels. Beneath the dermis lies the hypodermis (subcutaneous tissue), which is mostly fat and lies deeper than the skin proper. Since the epidermis has no blood vessels, it gets nutrients by diffusion from the vascular dermis. So the outermost, relatively thin layer you see and feel is the epidermis; the other options describe inner layers or tissues beneath the skin.