Question

Respiratory gas	Atmospheric air	Alveoli
$O_2$	159	A
$C{O}_2$	0.3	B

The table given shows the partial pressure values (in mm Hg) of oxygen and carbon dioxide in the alveoli in comparison to that in atmospheric air. Identify A and B and choose the correct option accordingly.

• A. A-50; B-50
• B. A-104; B-40
• C. A-40; B-104
• D. A-101; B-104

Answer 1

The correct option is B A-104; B-40

Pressure exerted by an individual gas in a mixture of gases is called partial pressure. Atmospheric air has a much greater concentration of oxygen compared to carbon dioxide and hence partial pressure of oxygen is much higher.

Within the alveoli the inspired air has a higher partial pressure of oxygen as compared to carbon dioxide. This causes oxygen to diffuse from the alveoli (higher partial pressure) into the blood (lower partial pressure) carried by the capillaries surrounding the alveoli.

Respiratory gas	Atmospheric air	Alveoli
$O_2$ (oxygen)	159	104
$C{O}_2$ (carbon dioxide)	0.3	40

Thus option b is correct.