Question

Interpret the given diagrams A and B. Enlist the changes occuring, during inspiration and expiration.

Answer 1

Diagram 'A' is of Inspiration.

Changes occurring during inspiration are as follows:

1. During inspiration, the atmospheric air is taken into the lungs.
2. It is an active process in which the diaphragm becomes flat and goes downward.
3. The intercostal muscles contract so the ribs and sternum move upward and outward.
4. This leads to an increase in the thoracic volume and a decrease in the pressure of the thorax and the lungs. To equalize the low pressure inside the lungs, air from the' atmosphere rushes into the lungs.

Diagram 'B' is of Expiration.

Changes occurring during expiration are as follows:

1. During expiration, the thorax contracts, causing air to be exhaled.
2. The diaphragm relaxes and is pushed upwards. It becomes dome-shaped.
3. The intercostal muscles also relax, pulling the rib cage inward and downward.
4. This causes a decrease in thoracic volume and leads to an increase in pressure in the thorax and the lungs. So air from the lungs rushes out.