Which epithelium forms the lining of the small intestine?

Which epithelium forms the lining of the small intestine?

• A. Simple cuboidal epithelium
• B. Transitional epithelium
• C. Simple columnar epithelium
• D. Simple squamous epithelium

Answer: (C)

The lining of the small intestine is designed for absorption and protection, and it consists of tall, single-layer cells called simple columnar epithelium. These cells form a continuous, single layer with nuclei toward the base, and their apical surfaces bear microvilli, creating a brush border that greatly increases surface area for nutrient uptake and enzyme activity. Goblet cells sprinkled among them secrete mucus to lubricate and protect the lining, while tight junctions between cells help regulate what passes through. Other epithelium types don’t support this function: simple squamous is a thin, diffusion-focused lining found in places like air sacs and blood vessels; simple cuboidal has shorter, cube-shaped cells suited to secretion and transport in glands and kidney tubules; transitional epithelium is specialized for stretch in the urinary tract.

The lining of the small intestine is designed for absorption and protection, and it consists of tall, single-layer cells called simple columnar epithelium. These cells form a continuous, single layer with nuclei toward the base, and their apical surfaces bear microvilli, creating a brush border that greatly increases surface area for nutrient uptake and enzyme activity. Goblet cells sprinkled among them secrete mucus to lubricate and protect the lining, while tight junctions between cells help regulate what passes through.

Other epithelium types don’t support this function: simple squamous is a thin, diffusion-focused lining found in places like air sacs and blood vessels; simple cuboidal has shorter, cube-shaped cells suited to secretion and transport in glands and kidney tubules; transitional epithelium is specialized for stretch in the urinary tract.