Final answer:
A large meal does not significantly impact lung function because the diaphragm and thoracic cavity can adjust accordingly, ensuring that lung volumes are maintained. The correct answer is (c) Increased abdominal size pushes on the diaphragm but doesn't affect lung volumes
Step-by-step explanation:
The question revolves around the impact of a large meal on lung function and how this was investigated in a research paper. The correct answer is c. Increased abdominal size pushes on the diaphragm but doesn't affect lung volumes. This is because, despite the fact that a full stomach can push on the diaphragm and reduce the space in the thoracic cavity, it does not significantly change the measure of air that the lungs can hold (total lung capacity). The study suggests that this is due to the diaphragm being remarkably adaptable and the inherent compliance of the thoracic cavity.
Thoracic wall compliance and the elasticity of lung tissues play a significant role in allowing for regular ventilation, even after a large meal. During inhalation, the diaphragm contracts and the intercostal muscles work to expand the thoracic cavity. During expiration, which is a passive process, these muscles relax and the elasticity of the lung tissue allows the lungs to recoil and air to be expelled. The ability to maintain lung volumes despite the increased abdominal size is a testament to the efficiency and adaptability of the respiratory system.