Which of the following is NOT part of the digestive system as listed?

Which of the following is NOT part of the digestive system as listed?

• A. Lungs
• B. Esophagus
• C. Large intestine
• D. Salivary glands

Answer: (A)

The main idea is to distinguish which organs belong to the digestive system versus other body systems. The digestive system includes the mouth, esophagus, stomach, small intestine, large intestine, and accessory organs like the salivary glands that help break down food, but it does not include the lungs. Lungs are part of the respiratory system, dedicated to gas exchange—oxygen in, carbon dioxide out. They don’t participate in digestion. The esophagus, large intestine, and salivary glands all play roles in digestion: the esophagus moves food toward the stomach through waves of muscle contractions, the salivary glands release saliva to begin chemical digestion and moisten food, and the large intestine absorbs water and forms waste. Because of their roles, the lungs are not part of the digestive system.

The main idea is to distinguish which organs belong to the digestive system versus other body systems. The digestive system includes the mouth, esophagus, stomach, small intestine, large intestine, and accessory organs like the salivary glands that help break down food, but it does not include the lungs.

Lungs are part of the respiratory system, dedicated to gas exchange—oxygen in, carbon dioxide out. They don’t participate in digestion. The esophagus, large intestine, and salivary glands all play roles in digestion: the esophagus moves food toward the stomach through waves of muscle contractions, the salivary glands release saliva to begin chemical digestion and moisten food, and the large intestine absorbs water and forms waste. Because of their roles, the lungs are not part of the digestive system.