What occurs during inhalation?

During inhalation, the diaphragm contracts, which increases the volume of the chest cavity. As the diaphragm moves downwards, this creates a negative pressure within the thoracic cavity compared to the atmospheric pressure outside the body. This pressure change allows air to flow into the lungs from outside, filling them with oxygen-rich air. The contraction of the diaphragm is a vital component of the breathing process, as it directly influences the mechanics of ventilation. The correct choice highlights this essential physiological action, differentiating inhalation from other respiratory processes, such as exhalation, when the diaphragm relaxes and volume decreases.

The other options either misrepresent the processes of inhalation or describe actions that occur during exhalation or other respiratory functions. Understanding the role of the diaphragm is crucial for grasping the fundamentals of respiratory physiology.