What does "atelectasis" describe in a medical context?

Atelectasis specifically refers to a condition where there is incomplete expansion or collapse of lung tissue, particularly affecting the alveoli, which are the tiny air sacs in the lungs responsible for gas exchange. When the alveoli are deflated, they cannot function properly for respiration, leading to reduced oxygenation of the blood and potential respiratory problems.

This definition aligns directly with the concept of atelectasis, emphasizing the state of the alveoli rather than other physiological changes or conditions. For example, fluid accumulation in the abdominal cavity pertains to conditions like ascites and is not relevant to atelectasis. Likewise, inflammation of the alveoli is known as pneumonitis, while a violation of the respiratory membrane would suggest a compromise in the surface necessary for gas exchange, which does not specifically denote the deflation of the alveoli themselves. Thus, the focus on deflated alveoli captures the essence of atelectasis accurately.