MHT CET 202621 AprilMorning Shift
- Exam
- MHT CET
- Year
- 2026
- Date
- 21 April
- Shift
- Morning Shift
- Subject
- Biology
- Chapter
- Breathing and Exchange of Gases
MHT CET 2026 · 21 April · Morning Shift · Biology · Breathing and Exchange of Gases
Which of the following does NOT occur during inspiration ?
Which of the following does NOT occur during inspiration ?
Options
- ARibs and sternum move upward and outward.
- BDiaphragm becomes flat.
- CIncrease in pressure of thorax and the lungs.
- DThe external intercostal muscles contract.
Correct answer
C. Increase in pressure of thorax and the lungs.
Step-by-step solution
During inspiration, the diaphragm contracts and becomes flat, increasing the volume of the thoracic cavity in the antero-posterior axis.
The external intercostal muscles contract, lifting the ribs and sternum upward and outward, which increases the volume of the thoracic cavity in the dorso-ventral axis.
The overall increase in thoracic volume leads to an increase in pulmonary volume.
According to Boyle's law, an increase in volume results in a decrease in pressure. Thus, the intra-pulmonary pressure decreases below atmospheric pressure, causing air to rush into the lungs.
An increase in the pressure of the thorax and lungs occurs during expiration, not inspiration.
Answer: Increase in pressure of thorax and the lungs.
The external intercostal muscles contract, lifting the ribs and sternum upward and outward, which increases the volume of the thoracic cavity in the dorso-ventral axis.
The overall increase in thoracic volume leads to an increase in pulmonary volume.
According to Boyle's law, an increase in volume results in a decrease in pressure. Thus, the intra-pulmonary pressure decreases below atmospheric pressure, causing air to rush into the lungs.
An increase in the pressure of the thorax and lungs occurs during expiration, not inspiration.
Answer: Increase in pressure of thorax and the lungs.