Which system performs gas exchange?

• A. Respiratory
• B. Cardiovascular
• C. Lymphatic
• D. Digestive

Answer: (A)

Gas exchange is performed by the respiratory system. In the lungs, oxygen from inhaled air diffuses across the thin walls of the alveoli into the surrounding capillaries, while carbon dioxide moves from the blood into the alveolar air to be exhaled. This exchange relies on differences in partial pressures and the large surface area provided by the alveoli. The respiratory system includes the airways and lungs where this exchange occurs. The cardiovascular system moves blood and nutrients, but doesn’t directly exchange gases with the air. The lymphatic system drains interstitial fluid and supports immunity, not gas exchange. The digestive system breaks down food and absorbs nutrients, not gases. So the system that performs gas exchange is the respiratory system.