Which system takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces)?

• A. Digestive system
• B. Nervous system
• C. Muscular system
• D. Skeletal system

Answer: (A)

Taking in food, breaking it down, absorbing nutrients, and eliminating unabsorbed matter as feces is the job of the digestive system. It begins with ingestion and both mechanical (chewing, churning) and chemical (saliva, enzymes) digestion to break bonds and make nutrients small enough to absorb. Most nutrients are absorbed in the small intestine, then any remaining waste moves to the large intestine to be eliminated. The other systems support body function, but they don’t carry out the full process of digestion and waste elimination. The nervous system coordinates activities, the muscular system enables movement, and the skeletal system provides structure. The digestive system uniquely handles nourishment and waste processing in one integrated pathway.