Question

The figure shows a diagrammatic view of human respiratory system with labels A, B, C and D. Select the option which gives correct identification and main function and / or characteristic.

• A. A-trachea long tube supported by complete cartilaginous rings for conducting inspired air
• B. B-pleural membrane – surround ribs on both sides to provide cushion against rubbing.
• C. C-Alveoli – thin walled vascular bag like structures for exchange of gases.
• D. D-Lower end of lungs – diaphragm pulls it down during inspiration.

Answer 1

The correct option is C C-Alveoli – thin walled vascular bag like structures for exchange of gases.

The alveoli are tiny air sacs within the lungs where oxygen and carbon dioxide exchange occurs. These pulmonary alveoli are the terminal ends of the respiratory tree.

C-Alveoli are thin-walled vascular bag-like structures for exchange of gases.
A-trachea or wind pipe is an air conducting tube through, which transport of gases takes place.

B-pleural membrane is double layered, which reduces friction on the lung surface.

D-diaphragm is involved in the inspiration and expiration process of breathing.

So, the correct answer is option C.