NEETZoologyBreathing and Exchange of Gases
Select the correct option according to the given diagram.
Options
- ARelaxation of the diaphragm and the intercostal muscles occur.
- BAn increase in intra-pulmonary pressure to slightly above the atmospheric pressure occurs
- CThe contraction of external intercostal muscles lifts up the ribs.
- DThere is reduction in Pulmonary volume in the above process.
Correct answer
C. The contraction of external intercostal muscles lifts up the ribs.
Step-by-step solution
Breathing involves two stages: inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiration takes place when t