A pressure change from 760 mmHg atmosphere to 757 mmHg in the alveoli allows what to happen?

A pressure change in the alveoli from 760 mmHg to 757 mmHg indicates a decrease in intrapulmonary pressure relative to atmospheric pressure (which is also typically around 760 mmHg). According to the principles of airflow and gas exchange, air moves from an area of higher pressure to an area of lower pressure. With the alveolar pressure at 757 mmHg being lower than the atmospheric pressure of 760 mmHg, this pressure gradient allows air to flow into the lungs.

During inhalation, when the diaphragm contracts and the thoracic cavity expands, the pressure within the alveoli decreases. As a result, external atmospheric air is drawn into the lungs to equalize the pressure. This is a crucial part of the breathing process, facilitating oxygen intake and carbon dioxide removal, which are essential for maintaining homeostasis in the body.