Which organ is primarily responsible for nutrient absorption and water reabsorption?

Which organ is primarily responsible for nutrient absorption and water reabsorption?

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

Answer: (B)

Think of the small intestine as the body’s main absorption highway. Its lining is folded into villi and microvilli, giving an enormous surface area for nutrients to be released from digested food and moved into the bloodstream or lymphatic system by specialized cells. Enzymes on the brush border finish digestion right at the surface, so sugars, amino acids, fatty acids, vitamins, and minerals can be absorbed efficiently. Water reabsorption happens here as the chyme flows through, with most of the water pulled back into the body before material reaches the colon. The stomach mainly breaks down food and digests with limited absorption, and the large intestine mainly reclaims water and electrolytes with less nutrient uptake. The liver processes nutrients after absorption, but it doesn’t absorb them directly from the gut lumen. So, the small intestine is the organ that handles both nutrient absorption and the bulk of water reabsorption.

Think of the small intestine as the body’s main absorption highway. Its lining is folded into villi and microvilli, giving an enormous surface area for nutrients to be released from digested food and moved into the bloodstream or lymphatic system by specialized cells. Enzymes on the brush border finish digestion right at the surface, so sugars, amino acids, fatty acids, vitamins, and minerals can be absorbed efficiently. Water reabsorption happens here as the chyme flows through, with most of the water pulled back into the body before material reaches the colon. The stomach mainly breaks down food and digests with limited absorption, and the large intestine mainly reclaims water and electrolytes with less nutrient uptake. The liver processes nutrients after absorption, but it doesn’t absorb them directly from the gut lumen. So, the small intestine is the organ that handles both nutrient absorption and the bulk of water reabsorption.