What occurs during the process of inhalation?

During the process of inhalation, the diaphragm contracts, which leads to an increase in the volume of the thoracic cavity. When the diaphragm moves downward, it creates a negative pressure in the pleural cavity, allowing the lungs to expand and draw air in through the airways. This increase in thoracic cavity volume decreases the pressure within the lungs compared to atmospheric pressure, causing air to flow into the lungs.

Understanding the mechanics of inhalation is crucial for comprehending respiratory physiology. The expansion of the thoracic cavity not only involves the diaphragm but also the intercostal muscles, which assist in elevating the ribs and further augmenting lung capacity. This process is essential for facilitating gas exchange, as it allows oxygen to enter the bloodstream and carbon dioxide to be expelled during exhalation. Consequently, the contraction of the diaphragm is a fundamental aspect of the inhalation process, making this the correct answer.