describe the mechanism of exchange of gases in the alveolus of the lung
Answers
The exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
ANSWER.......
☆☆ MECHANISM OF EXCHANGE OF GASES ☆☆
↪ Alveoli are the primary sites of exchange of cases. Exchange of gases also occurs between blood and tissues. O2 (oxygen) and CO2 ( carbondioxide) are exchanged in these sites by simple diffusion mainly based on pressure or concentration gradient. Solubility of the gases as well as the thickness of the membranes involved in diffusion are also some important factors that can affect the rate of diffusion.
↪ Pressure contributed by an individual has in a mixture of gases is called partial pressure and is represented by as pO2 for oxygen and pCO2 for carbon dioxide. Partial pressure of these two gases in the atmospheric air and the two sites of diffusion.
↪ A gradient is present for CO2 in the opposite direction i.e. from tissues to blood and blood to Alveoli. As the solubility of CO2 is 20-25 times higher than that of O2, the amount of CO2 that can diffuse through the diffusion membranes per unit difference in partial pressure is much higher compared to that of O2. The diffusion membrane is made up of three major layers namely, the thin squamous epithelium of Alveoli, endothelium of alveolar capillaries and the basement substances in between them. However, its total thickness is much less than a millimetre . Therefore, all the factors in our body are favourable for diffusion of O2 from Alveoli to tissues and that of Co2 from tissues to Alveoli.