Anatomy and Physiology II Practice Test

Where is the majority of nutrient absorption in the digestive tract primarily accomplished?

1. Jejunum

2. Ileum

3. Cecum

4. Duodenum

The correct answer is: Jejunum

The majority of nutrient absorption in the digestive tract primarily takes place in the jejunum. This section of the small intestine is specifically adapted for the absorption of carbohydrates, amino acids, fatty acids, vitamins, and minerals. The lining of the jejunum has numerous villi and microvilli, which increase the surface area significantly, allowing for more efficient absorption through its epithelial cells. In the jejunum, the pH is neutral to slightly alkaline, which optimally facilitates the action of digestive enzymes and promotes the absorption process. The presence of a rich blood supply further enhances the efficiency by ensuring that absorbed nutrients quickly enter the circulatory system. Other sections of the digestive tract play roles in digestion and absorption as well, but they are not as specialized for nutrient absorption as the jejunum is. For example, the duodenum is primarily responsible for the initial stages of digestion, particularly the mixing of chyme with bile and pancreatic juices, while the ileum primarily absorbs certain vitamins and bile salts. The cecum is mainly involved in the fermentation of undigested materials and does not play a significant role in nutrient absorption compared to the jejunum.