What is the function of the large intestine?

• A. Reabsorbs water and stores and eliminates undigested food
• B. Filtration
• C. Digestion
• D. Metabolism and Detoxification

Answer: (A)

The large intestine mainly reclaims water and forms and stores feces for elimination. After most nutrients have been absorbed in the small intestine, the remaining material still contains water and electrolytes. The large intestine absorbs much of that water and electrolytes, which concentrates the waste and helps form solid stool. It also houses bacteria that ferment some fibers, producing byproducts that can be absorbed, but it does not perform nutrient digestion to a significant extent. Its role is not filtration or detoxification—those functions belong to the kidneys and liver, respectively. So the best description is that it reabsorbs water and stores and eliminates undigested material.