Question

When the respiratory diaphragm contracts, it flattens, lowering the floor of the thoracic cavity. At the same time, the intercostal muscles pull the ribs up and out. The active forces of the muscle groups cause a(n) __________ (increase/decrease) in thoracic volume. Given the relationship between pressure and volume, this would cause pressure within the lungs to __________ (increase/decrease)

Answer 1

Answer:

1. Increase

2.  Decrease

Explanation:

During inspiration, diaphragm contracts and lowers down. There is a simultaneous contraction of external intercostal muscles and movement of rib-cage upward and outward. All these events lead to an increase in the volume of the thoracic cavity. Increase in volume of the thoracic cavity results in expansion of lungs and lowering down the air pressure within alveoli of lungs.