What happens to intrapleural pressure during inspiration?

During inspiration, the diaphragm and intercostal muscles contract to expand the thoracic cavity. This increases the volume of the thoracic cavity, which reduces the intrapleural pressure. The reduction in intrapleural pressure leads to it becoming more negative compared to its resting state. This negative pressure allows the lungs to expand as they fill with air from the atmosphere. The more negative intrapleural pressure creates a greater pressure gradient between the atmosphere and the lungs, facilitating the flow of air into the lungs during the process of inhalation. This mechanism is essential for effective ventilation and gas exchange.