AP BIOLOGY

Detailed explanation-1: -The small intestine has three parts: the duodenum, jejunum, and ileum. It helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. The small intestine is part of the digestive system.

Detailed explanation-2: -The small intestine is the most important organ of the digestive system as it serves both, for digestion and absorption. It receives two digestive juices; the bile and the pancreatic juice in the duodenum. These two juices virtually complete the digestion of starch, proteins, carbohydrates, etc.

Detailed explanation-3: -The small intestine is the most important absorbing organ in the GI tract. About 90% of nutrient absorption takes place in the small intestine.

Detailed explanation-4: -The duodenum is also a major site for absorption of iron. The jejunum is a major site for absorption of the vitamin folic acid and the end of the ileum is the most important site for absorption for the vitamin B12, and bile salts.

Detailed explanation-5: -Most people can live without a stomach or large intestine, but it is harder to live without a small intestine. When all or most of the small intestine has to be removed or stops working, nutrients must be put directly into the blood stream (intravenous or IV) in liquid form.