2nd October 2019


How does the pressure in the lungs change during inhalation and exhalation?

During the process of inhalation, the lung volume expands as a result of the contraction of the diaphragm and intercostal muscles (the muscles that are connected to the rib cage), thus expanding the thoracic cavity. Due to this increase in volume, the pressure is decreased, based on the principles of Boyle's Law.

Keeping this in view, why does the pressure in your lungs decrease when you breathe in?

When you inhale: the intercostal muscles contract, expanding the ribcage. the diaphragm contracts, pulling downwards to increase the volume of the chest. pressure inside the chest is lowered and air is sucked into the lungs.

What happens to intrathoracic pressure during expiration?

Air, following its pressure gradient, now flows into the lungs. During expiration, the diaphragm and external intercostal muscles relax, decreasing the volume of the thoracic cavity. The intrapleural pressure becomes less negative, the transpulmonary pressure decreases, and the lungs passively recoil.

What keeps the lungs inflated?

Intrapleural pressure is the pressure within the pleural cavity. Intrapleural pressure is always negative, which acts like a suction to keep the lungs inflated. The negative intrapleural pressure is due to three main factors: 1. The abundant elastic tissue in the lungs tends to recoil and pull the lung inward.
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