The respiratory system works with the circulatory system to accomplish what?

• A. Digest food
• B. Regulate body temperature
• C. Provide oxygen and remove waste carbon dioxide
• D. Filter blood

Answer: (C)

Gas exchange and transport between the respiratory and circulatory systems deliver oxygen to cells and remove carbon dioxide waste. Inhaled air brings oxygen into the lungs, where it passes through the alveolar membranes into the blood. Hemoglobin in red blood cells binds some of that oxygen and carries it through the bloodstream to tissues. Cells use oxygen to produce energy and constantly generate carbon dioxide as a waste product. That CO2 enters the blood (mostly as bicarbonate) and is carried back to the lungs, where it diffuses into the air inside the alveoli and is exhaled. This coordinated process is how the body keeps cells fueled and maintains proper pH and gas levels. The other options involve the digestive system (digesting food), temperature regulation through various mechanisms (while related, not the main collaborative purpose), or the kidneys and immune system (filtering blood), which are not the primary cooperative function of the respiratory and circulatory systems.