NEET PG DENTAL EXAM

Detailed explanation-1: -When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside.

Detailed explanation-2: -[1] Increasing the volume of the thoracic cavity causes a decrease in the intrathoracic pressure and an influx of air. Meanwhile, decreasing the volume of the thoracic cavity generally occurs by the relaxation of the muscles of inspiration, which causes an increase in intrathoracic pressure and results in exhalation.

Detailed explanation-3: -During inspiration, the diaphragm and external intercostal muscles contract, causing the rib cage to expand and move outward, and expanding the thoracic cavity and lung volume.

Detailed explanation-4: -The pleural cavity always maintains a negative pressure. During inspiration, its volume expands, and the intrapleural pressure drops. This pressure drop decreases the intrapulmonary pressure as well, expanding the lungs and pulling more air into them. During expiration, this process reverses.