Which system moves oxygen into the blood stream to be carried to the body and moves gas waste out of the body (CO2)?

• A. Nasal mucous membrane
• B. Lumbar puncture
• C. EEG
• D. Respiratory system

Answer: (D)

Gas exchange happens in the respiratory system. It brings in oxygen from the air into the lungs and passes it into the bloodstream, where it travels to tissues throughout the body. At the same time, carbon dioxide, a waste product of metabolism, moves from the blood into the lungs to be exhaled. This coordinated exchange is the core function of the respiratory system, involving the airways, lungs, alveoli, and the diaphragm that drives breathing.

The nasal mucous membrane is part of the airway and helps filter, warm, and humidify air, but it doesn’t move gases into the bloodstream or remove CO2. A lumbar puncture collects cerebrospinal fluid, not related to gas exchange. An EEG records brain electrical activity, not respiratory gas exchange.