Arizona State University (ASU) BIO202 Human Anatomy and Physiology II Exam 2 Practice Exam

The diffusion of gases during respiration is primarily driven by concentration gradients. This phenomenon occurs because gases move from areas of higher concentration to areas of lower concentration in order to reach equilibrium. In the context of respiration, oxygen from the air in the alveoli of the lungs diffuses into the blood, where the concentration of oxygen is lower. Conversely, carbon dioxide, which is present in higher concentrations in the blood than in the alveoli, diffuses from the blood into the alveoli to be exhaled.

While pressure gradients can also influence gas exchange—since gases naturally move from areas of higher pressure to lower pressure—the fundamental mechanism that regulates the movement of oxygen and carbon dioxide during respiration is the difference in their concentrations in the respective areas. Thus, concentration gradients are the primary driving force facilitating this movement and ensuring efficient gas exchange, which is vital for maintaining cellular respiration and overall metabolic function.