Zoology - Breathing and Exchange of Gases Question with Solution | TestHub

The human respiratory system has a very high number of alveoli to maximize exchange rate of gases. Small size and high count increases the surface area for better exchange of gases. The exchange site (alveoli and capillary) consists of thin layer (single layer of cells) to provide short distance for smooth diffusion. For keeping high gradient, the blood reaching the exchange site is very low in${\mathrm{O}}_2$level and air taken in has very high concentration of${\mathrm{O}}_2$comparatively enabling better diffusion. Blood flow within the pulmonary system is on the lower side to enable better gas exchange. If blood flow is high it will reduce the contact time for RBC to exchange carbon dioxide for oxygen. Increase in thickness of the respiratory membrane decreases the efficiency of gas exchange.