Final answer:
Oxygen and carbon dioxide are exchanged between the alveoli and capillaries through diffusion, driven by differences in partial pressure. Oxygen binds to hemoglobin in red blood cells, and carbon dioxide is expelled during exhalation.
Step-by-step explanation:
The mechanism that allows oxygen to move into the blood and carbon dioxide to move into the alveoli is known as diffusion. This process occurs in the alveoli, tiny sacs within the lungs. Oxygen moves from the alveoli, where its concentration is higher, into the blood in the capillaries that surround the alveoli. Simultaneously, carbon dioxide moves from the higher concentration in the capillary blood to the lower concentration in the alveoli. These movements are driven by differences in partial pressure between the alveoli and the capillaries, allowing for the efficient exchange of gases. In more technical terms, oxygen diffuses across the alveolar walls and binds to hemoglobin in the red blood cells. This oxygen-rich blood is then transported throughout the body. Conversely, carbon dioxide diffuses from the blood into the alveoli to be exhaled. The partial pressures of oxygen and carbon dioxide are crucial for this exchange and are affected by both deep and forced breathing, which can alter the composition of alveolar air more rapidly than quiet breathing.