What part of the following description is incorrect?
a. contraction of the diaphragm and external intercostal muscles leads to increased volume in the thoracic cavity and the lungs.
b. the increase in volume leads to an increase in intrapulmonary pressure causing air to move into the lungs.

b.The increase in volume leads to an increase in intrapulmonary pressure causing air to move into the lungs.

Explanation:

The two lungs are the main organs of the respiratory system. Other components of the respiratory system carry air to the lungs, such as the trachea, which branches into smaller structures called bronchial tubes.

The breathing process is divided into two distinct phases: inspiration (inhalation) and expiration (exhalation). During inspiration, the diaphragm contracts and falls, while the muscles between the ribs contract and rise. This increases the size of the rib cage and reduces internal pressure. As a result, air rushes in and fills the lungs.

During expiration, the diaphragm relaxes and the volume of the rib cage decreases, while the pressure inside it increases. Consequently, the lungs contract and the air is expelled outward.