Effusion refers to what process?

Effusion specifically refers to the process where fluid accumulates in a body cavity, such as the pleural cavity surrounding the lungs. This accumulation can occur due to various medical conditions, including infection, inflammation, or malignancy. The presence of excess fluid can lead to symptoms like difficulty breathing or chest pain, depending on the cavity involved and the amount of fluid present.

The other options describe different processes. For instance, the escape of air into the lungs is related to inhalation and involves the respiratory system. The escape of blood into tissue refers to hemorrhage or bruising, which occurs when blood vessels are damaged. Finally, the escape of gas from the stomach pertains to the release of gas as flatulence or belching, which is a normal digestive process. These definitions highlight the specific nature of effusion in comparison to other physiological processes in the body.