What is the primary function of the small intestine?

What is the primary function of the small intestine?

• A. Absorption of nutrients
• B. Production of bile
• C. Filtering of blood
• D. Mechanical digestion

Answer: (A)

The main idea being tested is the small intestine’s job in digestion: absorbing nutrients. Its lining is folded into villi and microvilli, creating a very large surface area that mucus and enzymes work on as chyme passes through. This setup allows nutrients from digested carbohydrates, proteins, and fats to be taken across the intestinal wall into the bloodstream (for sugars and amino acids) or into the lymphatic system (for fats). Bile is made by the liver and released into the small intestine to help fat digestion, but production isn’t a function of the small intestine itself. Filtering of blood happens mainly in the liver and kidneys, not in the small intestine, and mechanical digestion is more about breaking things down with teeth and stomach movements, with segmentation in the small intestine aiding mixing rather than serving as the primary role. So the central, defining function here is absorbing nutrients.

The main idea being tested is the small intestine’s job in digestion: absorbing nutrients. Its lining is folded into villi and microvilli, creating a very large surface area that mucus and enzymes work on as chyme passes through. This setup allows nutrients from digested carbohydrates, proteins, and fats to be taken across the intestinal wall into the bloodstream (for sugars and amino acids) or into the lymphatic system (for fats). Bile is made by the liver and released into the small intestine to help fat digestion, but production isn’t a function of the small intestine itself. Filtering of blood happens mainly in the liver and kidneys, not in the small intestine, and mechanical digestion is more about breaking things down with teeth and stomach movements, with segmentation in the small intestine aiding mixing rather than serving as the primary role. So the central, defining function here is absorbing nutrients.