Final answer:
Gas exchange in the lungs and tissues operates through diffusion, dependent on the difference in partial pressure of gases, with oxygen and carbon dioxide moving along their respective gradients.
Step-by-step explanation:
Gas exchange between lungs and tissues occurs via diffusion and depends on the difference in partial pressure of the specific gas. Both external respiration in the lungs and internal respiration in tissues rely on diffusion, which is a passive process driven by partial pressure gradients, requiring no energy input.
The pressure gradient for any given gas, such as oxygen or carbon dioxide, determines the direction in which the gas will diffuse. For example, oxygen flows from areas of high partial pressure in the lungs to areas of low partial pressure in the blood, while carbon dioxide flows from high to low partial pressure from blood to lungs. This movement is essential for bringing oxygen to tissues for cellular respiration and removing the byproduct carbon dioxide.