Name the three basic shapes of epithelial cells and give a typical location for each.

• A. Squamous: lung lining; Cuboidal: kidney tubules; Columnar: intestinal lining
• B. Squamous: lung alveoli and blood vessel lining; Cuboidal: kidney tubules; Columnar: intestinal lining
• C. Squamous: lining of blood vessels and alveoli; Cuboidal: kidney tubules; Columnar: intestinal lining
• D. Squamous: lung alveoli, lining of blood vessels; Cuboidal: kidney tubules; Columnar: intestinal lining

Answer: (D)

Three basic epithelial cell shapes are squamous (flat), cuboidal (cube-shaped), and columnar (tall). Squamous epithelium is very thin, which makes it ideal for diffusion and filtration. That’s why you find it lining places where rapid exchange occurs, such as the air sacs in the lungs (alveoli) and the inner lining of blood vessels (endothelium). Cuboidal epithelium consists of cube-like cells and is common in tissues involved in absorption and secretion, with kidney tubules being a classic example. Columnar epithelium is tall and geared toward absorption and secretion, typical of the intestinal lining.

So the best match is squamous in the lung alveoli and the lining of blood vessels, cuboidal in kidney tubules, and columnar in the intestinal lining. This pairing reflects the functional advantages of each shape in those locations.