What is the mechanism of ventilation when atmospheric pressure is greater?

The mechanism of ventilation is fundamentally influenced by the differences in atmospheric pressure and the pressure within the lungs. When atmospheric pressure is greater than the pressure within the lungs, this creates a pressure gradient that encourages air to flow into the lungs. This process occurs during the inhalation phase of breathing, where the diaphragm and intercostal muscles contract, expanding the thoracic cavity and lowering the pressure inside the lungs.

As the atmospheric pressure exceeds the intrapulmonary pressure, air naturally moves from an area of higher pressure (the outside atmosphere) to an area of lower pressure (the lungs). This principle is a part of Boyle's Law, which states that the pressure of a gas is inversely proportional to its volume. In summary, when the atmospheric pressure is greater, it facilitates the influx of air into the lungs, which is essential for respiration and gas exchange.