What is the primary function of the lungs in the respiratory system?

The primary function of the lungs in the respiratory system is to exchange carbon dioxide and oxygen. The lungs are crucial for the process of gas exchange, where oxygen from the air we breathe enters the bloodstream, and carbon dioxide, a waste product of metabolism, is expelled from the blood into the air to be exhaled. This exchange occurs in the alveoli, tiny air sacs within the lungs that facilitate the diffusion of gases due to their large surface area and thin walls.

Oxygen is essential for cellular respiration, the process by which cells generate energy in the form of ATP. The efficiency of this vital exchange process impacts overall health and physical performance, as adequate oxygen supply is necessary for sustaining energy levels during physical activities.

The other functions listed are unrelated to the primary role of the lungs. For instance, pumping blood through blood vessels is the primary role of the heart. Producing ATP from glucose primarily occurs in the mitochondria of cells during cellular respiration, and while immune cells do operate in the lungs, their activity is a supportive function rather than a primary role of the lungs in respiration.