MHT CET Medical202621 April 2026Evening ShiftBiologyBreathing and Exchange of GasesActual
Which of the following doesn't happen during inspiration?
Options
- AThe intercostal muscle contract
- BThe ribs are pulled outward
- CThe diaphragm lifts upward
- DVolume of thoracic cavity increases
Correct answer
C. The diaphragm lifts upward
Step-by-step solution
During inspiration, the diaphragm contracts and moves downward (flattens), which increases the volume of the thoracic cavity in the antero-posterior axis. It does not lift upward. The lifting upward of the diaphragm occurs during expiration when it relaxes and returns to its original dome shape. The external intercostal muscles contract, pulling the ribs and sternum upward and outward, which increases the volume of the thoracic cavity in the dorso-ventral axis. This overall increase in thoracic volume leads to a de