The pulmonary alveolus, also known as the lung air sac, is a vital part of the respiratory system. It is responsible for allowing gas exchange between the lungs and the blood vessels. There are several synonyms for pulmonary alveolus, such as air sac, alveolar sac, air cell, and respiratory sac. These terms can be used interchangeably when referring to this important structure. Understanding the different synonyms for pulmonary alveolus can help simplify communication between medical professionals and improve patient care. It is essential to have a clear understanding of the terminology used in the medical field to ensure accurate diagnosis and treatment.