Which organ is the primary site of nutrient absorption?

• A. Liver
• B. Stomach
• C. Small intestine
• D. Large intestine

Answer: (C)

Nutrient absorption happens mainly in the small intestine because its lining has a huge surface area, with folds, villi, and microvilli that dramatically increase the amount of contact between digested nutrients and the absorptive cells. This specialized surface lets carbohydrates, proteins, and fats that have been broken down by enzymes pass into the bloodstream and, for fats, into the lymphatic system as they’re packaged into chylomicrons.

While the stomach does a lot of the mechanical and chemical digestion, it absorbs only small amounts of water, alcohol, and some medications. The large intestine mainly pulls water and electrolytes from indigestible food and hosts gut bacteria that can make some vitamins, but it’s not where most nutrients enter the body. The liver processes absorbed nutrients after they reach the bloodstream, but it isn’t the site of absorption itself.

So, the organ that serves as the primary site of nutrient absorption is the small intestine.