Question

The figure shows a diagrammatic view of the 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 - surrounds ribs on both sides to provide a cushion against rubbing
C.) C - Alveoli, a thin-walled vascular bag like structures for exchange of gases
D.) D- the lower end of lungs - diaphragm pulls it down during inspiration

Answer 1

Respiration is the basic necessity of the body to stay alive. The oxygen we need to breathe is obtained from the environment. We purify it in the lungs and release the carbon dioxide outside in the atmosphere.

Complete answer:

The human respiratory system signifies the exchange of gases. It has very minute vessels to filter out the oxygen to make it available to the whole body.

The inspired air is the air with more oxygen and expired air is the one expelled from the lungs having more of the carbon dioxide.

Option A: A - trachea - long tube supported by complete cartilaginous rings for conducting inspired air: The trachea is the long hollow tube connecting the larynx and bronchi of lungs. It has both expired and inspired air in it.

Option B: B - pleural membrane - surrounds ribs on both sides to provide a cushion against rubbing: the outer membrane of the lungs is called the parietal pleura. It is attached to the chest wall. It has ribs on only the outer side and lungs on the inner side.

Option C: C - Alveoli, a thin walled vascular bag like structures for exchange of gases: alveoli are the tiny sacs in the lungs where the exchange of the gases like carbon dioxide and oxygen occurs. They are the terminal regions of the respiratory tree.

Option D: D- the lower end of lungs - Diaphragm is a dome-shaped, muscular and membranous structure that separates the thoracic (chest) and abdominal cavities in mammals; it is the principal muscle of respiration. The D signifies the diaphragm. It is the lower end of the lungs but is named diaphragm.

So the answer is option C: C - Alveoli, a thin-walled vascular bag like structures for exchange of gases.

Note: There are various organs used for respiration for different organisms. The gills are used for aquatic animals. Lungs in humans never remain germ-free. The lungs can even float in water. The lungs always have a minute amount of air.