Alveoli are small, air-filled sacs in the lungs that are responsible for the exchange of oxygen and carbon dioxide. The primary way that alveoli get rid of CO2 is through exhalation. When a person inhales, oxygen enters the alveoli, and when they exhale, CO2 is released.
Gas Exchange
The process of gas exchange occurs when oxygen and CO2 move between the alveoli and the bloodstream. Oxygen moves from the alveoli into the bloodstream and is then delivered to the body's cells. At the same time, CO2 moves from the bloodstream into the alveoli and is then expelled when a person breathes out.
Diffusion
The gas exchange process is driven by diffusion, which is the movement of molecules from an area of higher concentration to an area of lower concentration. In the alveoli, the concentration of oxygen is higher than the concentration of CO2. This means that oxygen molecules will move from the alveoli into the bloodstream, while CO2 molecules will move from the bloodstream into the alveoli.
Surfactant
Alveoli are lined with a substance called surfactant. This substance helps to reduce the surface tension of the alveoli and makes it easier for oxygen and CO2 to move across the alveolar walls. Without surfactant, the alveoli would not be able to exchange gases effectively.
Pressure Differential
The exchange of gases is also facilitated by a pressure differential between the alveoli and the bloodstream. The alveoli are at a lower pressure than the bloodstream, so oxygen moves from the alveoli into the bloodstream, and CO2 moves from the bloodstream into the alveoli.
In summary, alveoli get rid of CO2 by exhalation. The process of gas exchange is driven by diffusion, and facilitated by surfactant and a pressure differential between the alveoli and the bloodstream.
