Which organ does NOT belong in the respiratory system?

The stomach does not belong to the respiratory system because it is a crucial part of the digestive system, which is responsible for breaking down food and absorbing nutrients. The primary organs associated with the respiratory system include the larynx, trachea, and alveoli.

The larynx serves as a passage for air and plays a role in producing sound, while the trachea is the windpipe that connects the throat and lungs, allowing air to flow in and out. Alveoli are small air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs during respiration.

In contrast, the stomach's function is entirely separate; it processes food through digestion and is not involved in breathing or gas exchange. This distinct separation of functions clearly identifies the stomach as not being part of the respiratory system.