Final answer:
Digestion and absorption primarily occur in the small intestine, with specific nutrients being absorbed in different sections such as carbohydrates and proteins in the jejunum and vitamin B12 and bile salts in the ileum.
Step-by-step explanation:
The Site of Digestion and Absorption
The majority of digestion and absorption of nutrients from food occurs in the small intestine. Beginning in the mouth, digestion involves a series of enzymatic reactions that break down carbohydrates, proteins, and lipids. The process then continues through the small intestine where the enzymes and bile facilitate further digestion. The small intestine's three main parts - the duodenum, jejunum, and ileum - play key roles, with the jejunum being primarily responsible for the absorption of carbohydrates and proteins, and the ileum being essential for the absorption of vitamin B12 and bile salts. The large intestine's role is mainly to reabsorb water and some vitamins, as well as the elimination of waste in the form of feces.