Which organ system is primarily responsible for digestion and nutrient absorption?

• A. GI
• B. Musculoskeletal
• C. Nervous
• D. Endocrine

Answer: (A)

The main concept being tested is which organ system handles digestion and nutrient absorption. The gastrointestinal system is specialized for breaking down food and taking up nutrients. Digestion starts in the mouth with chewing and saliva, then continues in the stomach where acid and enzymes further break down food. The small intestine is the main site of absorption, where enzymes from the pancreas and bile from the liver aid digestion and nutrients pass into the bloodstream through the lining’s villi and microvilli. While the large intestine mainly reclaims water, the overall process of chemical and mechanical breakdown and nutrient uptake occurs within the GI tract and its accessory organs (liver, pancreas, gallbladder).

The other systems aren’t primarily responsible for digestion and absorption. The musculoskeletal system provides structure and movement, the nervous system coordinates processes, and the endocrine system regulates digestion with hormones, but the actual digestion and nutrient absorption occur in the gastrointestinal system.