Biology - Breathing and Exchange of Gases Question with Solution | TestHub

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 decrease in intrapulmonary pressure, causing air to move into the lungs.

Answer: The diaphragm lifts upward