Final answer:
Ventilation and transport of gases in the blood rely on diffusion based on partial pressure differences. Oxygen and carbon dioxide move independently via their gradients, with oxygen being particularly carried by hemoglobin in red blood cells.
Step-by-step explanation:
Ventilation and transport of gases in the blood stream occur via diffusion, which depends on the difference in partial pressure. The process of ventilation moves air into and out of the alveoli, whereas perfusion pertains to the flow of blood through the capillaries. Both of these processes are crucial for effective gas exchange, which is essentially the transfer of oxygen and carbon dioxide between the blood and the alveoli in the lungs.
Oxygen and carbon dioxide move down their respective pressure gradients, each diffusing from regions of higher partial pressure to those of lower partial pressure. In the pulmonary capillaries, the oxygen partial pressure (Po₂) is typically higher than in the blood, driving oxygen into the blood where it is carried primarily by hemoglobin in erythrocytes. Conversely, carbon dioxide moves from the blood, where its partial pressure (Pco₂) is higher, into the alveoli to be exhaled.