Which organ is primarily responsible for breaking down lactose, maltose, and sucrose?

Which organ is primarily responsible for breaking down lactose, maltose, and sucrose?

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

Answer: (A)

The key idea is where disaccharides are turned into absorbable sugars. That work happens in the small intestine, where enzymes on the lining of the gut—lactase, maltase, and sucrase—break down the three disaccharides into monosaccharides. Lactase cuts lactose into glucose and galactose, maltase splits maltose into two glucose molecules, and sucrase splits sucrose into glucose and fructose. Once in monosaccharide form, these sugars are ready to be absorbed into the bloodstream via the intestinal lining. The stomach isn’t where this digestion occurs; it mainly uses acid and proteases to digest proteins, not these carbohydrates. The esophagus is just a passageway with no digestion. The large intestine can ferment some undigested sugars, but the actual breakdown into absorbable monosaccharides happens in the small intestine.

The key idea is where disaccharides are turned into absorbable sugars. That work happens in the small intestine, where enzymes on the lining of the gut—lactase, maltase, and sucrase—break down the three disaccharides into monosaccharides. Lactase cuts lactose into glucose and galactose, maltase splits maltose into two glucose molecules, and sucrase splits sucrose into glucose and fructose. Once in monosaccharide form, these sugars are ready to be absorbed into the bloodstream via the intestinal lining.

The stomach isn’t where this digestion occurs; it mainly uses acid and proteases to digest proteins, not these carbohydrates. The esophagus is just a passageway with no digestion. The large intestine can ferment some undigested sugars, but the actual breakdown into absorbable monosaccharides happens in the small intestine.