The pulmonary acinus is a functional unit of the lung that is responsible for gas exchange between the air and the blood. It is the smallest subdivision of the lung that contains both respiratory bronchioles and alveolar ducts.
The pulmonary acinus consists of a series of branching airways that lead to small sacs called alveoli. These alveoli are the site of gas exchange, where oxygen is taken up by the blood and carbon dioxide is released into the air.
The respiratory bronchioles are the first branches of the pulmonary acinus and contain small airways that are lined with ciliated cells and mucus-secreting cells. These cells help to protect the lungs from inhaled particles and pathogens.
The alveolar ducts are small tubes that lead to clusters of alveoli. These ducts are lined with smooth muscle and are responsible for regulating airflow to the alveoli.
The walls of the alveoli are very thin and are lined with capillaries. This allows for efficient exchange of gases between the air and the blood. Oxygen from the air diffuses across the alveolar walls and into the blood, while carbon dioxide from the blood diffuses across the alveolar walls and into the air.
The structure of the pulmonary acinus is important for maintaining normal lung function. Damage to any part of the acinus can lead to impaired gas exchange and respiratory failure. Diseases that affect the acinus include chronic obstructive pulmonary disease (COPD), emphysema, and bronchitis.
In summary, the pulmonary acinus is a small functional unit of the lung that plays a critical role in gas exchange. It consists of respiratory bronchioles, alveolar ducts, and alveoli, which work together to facilitate the exchange of oxygen and carbon dioxide between the air and the blood.
