Epithelial cells are best described as

• A. Skin cells that cover the outside of the body and line the internal surfaces
• B. Neurons that conduct impulses
• C. Fibroblasts that synthesize collagen
• D. Blood cells that transport oxygen

Answer: (A)

Epithelial tissue forms continuous cellular sheets that cover body surfaces and line hollow organs and cavities. Epithelial cells provide a protective barrier, and they also handle absorption and secretion, with many specialized to form glands. This is why describing epithelial cells as skin cells that cover the outside of the body and line the internal surfaces is the best fit. They are typically avascular and rely on diffusion from underlying tissues for nutrients, and they continually renew from stem cells in the deeper layer.

Neurons are nerve cells that conduct impulses, fibroblasts are connective-tissue cells that synthesize collagen, and blood cells transport oxygen; these are different tissue types with distinct roles, not epithelial cells.