What is the pressure inside the alveoli called?

• A. Intrapulmonary pressure
• B. Alveolar pressure
• C. Atmospheric pressure
• D. Intrapleural pressure

Answer: (B)

The pressure inside the alveoli is known as alveolar pressure. This pressure is essential in the mechanics of ventilation, as it refers specifically to the pressure in the alveoli during the respiratory cycle. It plays a critical role in gas exchange, as it facilitates the movement of air in and out of the lungs.

During inhalation, the alveolar pressure decreases compared to atmospheric pressure, which allows air to flow into the lungs. Conversely, during exhalation, the alveolar pressure increases, pushing air out of the lungs. Understanding alveolar pressure is crucial for grasping how ventilation works and how oxygen and carbon dioxide are exchanged in the respiratory system.

Intrapulmonary pressure is often used interchangeably with alveolar pressure, but it can refer more generally to the pressure within the entire lung's airway, not just the alveoli themselves. Atmospheric pressure is the pressure exerted by the weight of the atmosphere and is not specific to the inside of the lungs. Intrapleural pressure refers to the pressure within the pleural cavity, which serves a different function in maintaining lung expansion and preventing collapse.