BIO 140 Human Biology I - Questions and Solutions

1. Explain how nutrients absorbed in the small intestine pass into the general circulation.

Solution: Nutrients from the breakdown of carbohydrates and proteins are absorbed through a capillary bed in the villi of the small intestine. Lipid breakdown products are absorbed into a lacteal in the villi, and transported via the lymphatic system to the bloodstream.

2. Why is it important that chyme from the stomach is delivered to the small intestine slowly and in small amounts?

Solution: If large quantities of chyme were forced into the small intestine, it would result in osmotic water loss from the blood into the intestinal lumen that could cause potentially life-threatening low blood volume and erosion of the duodenum.

3. Describe three of the differences between the walls of the large and small intestines.

Solution: The mucosa of the small intestine includes circular folds, villi, and microvilli. The wall of the large intestine has a thick mucosal layer, and deeper and more abundant mucus-secreting glands that facilitate the smooth passage of feces. There are three features that are unique to the large intestine: teniae coli, haustra, and epiploic appendages.