Which system is responsible for taking in oxygen and releasing carbon dioxide using the lungs?

• A. Respiratory system
• B. Circulatory system
• C. Nervous system
• D. Endocrine system

Answer: (A)

The respiratory system is responsible for taking in oxygen and releasing carbon dioxide using the lungs. When you breathe in, air travels to the lungs where oxygen passes through the thin walls of tiny air sacs called alveoli into surrounding blood vessels. At the same time, carbon dioxide travels from the blood into the alveoli to be exhaled. This gas exchange happens because of differences in gas pressures between the air in the alveoli and the blood. The circulatory system then carries the oxygen-rich blood to the body and brings carbon dioxide back to the lungs for removal. The nervous and endocrine systems influence breathing, but the actual exchange of oxygen and carbon dioxide through the lungs is the job of the respiratory system.