Question

what is true about the life - span of epithelial cells that form the inner lining of the small intestine?
multiple choice
they are replaced every few days.
they are not able to reproduce.
they are formed during development and last a lifetime.
they are replaced every few years.

Explanation:

Epithelial cells in the small intestine's inner lining are constantly exposed to mechanical and chemical stress from digestion. To maintain the integrity of the intestinal barrier, these cells have a high turnover rate. They are replaced frequently. Cells that cannot reproduce would not be able to maintain the lining. Cells formed during development and lasting a lifetime would not be able to handle the wear - and - tear. A few years is too long for such a highly stressed tissue. Every few days is consistent with the need for rapid replacement.

Answer:

They are replaced every few days.