Majority of what occurs in the small intestines?

• A. Mechanical digestion only
• B. Chemical digestion, nutrient absorption
• C. Water absorption only
• D. Protein synthesis

Answer: (B)

The small intestine’s primary role is chemical digestion and nutrient absorption. Enzymes from the pancreas and brush-border enzymes finish breaking down carbohydrates into simple sugars, proteins into amino acids, and fats into fatty acids and monoglycerides. The lining’s villi and microvilli provide a huge surface area, allowing these digested nutrients to be efficiently absorbed into the bloodstream or lymphatic system. Mechanical digestion happens there too, mainly to mix and move contents, but it isn’t the main activity. Water absorption also occurs along the small intestine as part of the absorption process. Protein synthesis isn’t a main function of the small intestine; it’s carried out by other tissues and cells throughout the body.