Question:

Alveoli are the primary sites for exchange of gases. All factors in our body are favourable for diffusion of $O_2$ from alveoli to tissues and that of $CO_2$ from tissues to alveoli.

Updated On: Jul 6, 2022

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false

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The Correct Option is B

Solution and Explanation

The solubility of the gases as well as the thickness of the membranes involved in diffusion are important factors that affect the rate of diffusion. A gradient of partial pressure is present for oxygen from alveoli to blood and blood to tissue. Similarly, a gradient of $CO_2$ is present in the opposite direction i.e., from tissues to blood and blood to alveoli. It is further dependent on the solubility of the diffusing gases. As the solubility of $CO_2$ is $20-25$ times higher than that of $O_2$, the amount of $CO_2$ that can diffuse through the diffusion membrane per unit difference in partial pressure is much higher compared to that of $O_2$. Therefore, all the factors in our body are favourable for diffusion of $O_2$ from alveoli to tissues and that of $CO_2$ from tissues to alveoli. Alveolus is the primary site of exchange as it has an extensive network of blood capillaries and consists of squamous epithelium. Due to very intimate contact of blood capillaries with the alveoli, the exchange of gases takes place easily.

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Notes on Exchange Of Gases

Concepts Used:

Breathing and Exchange of Gases

A metabolic process, which is carried out by all living organisms including plants, animals, and humans for the production of energy and to stay alive is Respiration. Except for required anaerobes, every other organism from amoeba to humans needs oxygen for survival. And evolution has reported a number of systems that allows the exchange of gases in organisms.

There are two types of respiration such as;

Aerobic respiration — to produce energy, it occurs in the presence of oxygen
Anaerobic respiration — to produce energy, occurs in the absence of oxygen

Breathing can be simply derived as the process of inhaling oxygen gas from the atmosphere and exhaling the carbon dioxide gas back into the atmosphere is termed breathing and the process is commonly known as respiration.