Question

The given diagram shows a blood capillary in close contact with structure Y. The relative concentration (in units) of carbon dioxide (CO2​) and oxygen (O2​) are given at three different sites.
Which of the following statements is correct?

A)Y is an alveolus and blood flow is from X to Z.
B)Y is an alveolus and blood flow is from Z to X.
C)Y is a muscle and blood flow is from X to Z.
D)Y is a muscle and blood flow is from Z to X.

Answer 1

Hint: Gas exchange takes place in the alveoli to load oxygen into the bloodstream and unload carbon dioxide from the bloodstream. Oxygen diffuses through the cells of the tissues, while carbon dioxide diffuses through the circulation and from the cells of the tissues.

Complete answer:
The method of absorbing inhaled ambient oxygen molecules into the bloodstream and unloading carbon dioxide into the atmosphere from the bloodstream is gas exchange. In the lungs, this process is achieved by the diffusion of gases from high-concentration areas to low-concentration areas.

The motion occurs in the lungs and the vessels that wrap them in a vast number of alveoli. Inhaled oxygen travels from the alveoli to the blood in the vessels, and carbon dioxide moves from the blood in the vessels to the air in the alveoli, as seen in the diagram.

Hence, the correct answer is option (B)

Note: For the conversion of oxygen from the outer world to the blood that passes through the lungs, three mechanisms are vital: ventilation, diffusion, and perfusion. The mechanism by which air passes in and out of the lungs is ventilation