Final answer:
Most nutrient absorption occurs in the small intestine, particularly in the jejunum, facilitated by its large surface area and specialized structures like villi and microvilli.
Step-by-step explanation:
The small intestine is where most absorption takes place in the human body. It is the primary digestive organ and is about 10 feet long, which gives it a large surface area for absorption. Almost all ingested food, 80 percent of electrolytes, and 90 percent of water are absorbed in the small intestine, with most absorption of carbohydrates and proteins occurring in the jejunum.
The organ in which most absorption takes place is the small intestine. Although some absorption occurs in the stomach and large intestine, about 95 percent of nutrient molecules are absorbed in the small intestine, particularly in the jejunum. The small intestine's enormous surface area, which is further increased by structural adaptations such as circular folds, villi, and microvilli, allows for efficient absorption of nutrients. These structures house millions of microvilli, which contain brush border enzymes that complete the digestion of carbohydrates and proteins. The migratory motility complexes in the small intestine also help propel the chyme and increase the opportunity for nutrient absorption.