Pulmonary alveoli are part of the respiratory system.
Function of pulmonary alveoli
The pulmonary alveoli are located in the deepest part of the lung at the end of the bronchioles and are the basic structure where gas exchange occurs between the organism and the external air.
Type 2 pneumocytes secretes surfactant, the viscous liquid reduces the surface tension of the alveoli to avoid them collapsing in on themselves during the expiratory phase. Macrophages are also present to provide the lung with immunity.
Structure of the alveoli
The alveoli are located at the end of the bronchioles and are small sacks (0.1 millimetres) with very thin walls to facilitate gas exchange (0.2 micrometers).
The alveoli are made up of membrane (type 1) and granular (type 2) pneumocytes.
There are 300 million of these per lung making a total gas exchange surface to the lungs of 130 square meters. They are surrounded by capillaries which provide oxygen to the blood and which return the re-oxygenated blood to the lung.
The pulmonary alveoli are located at the end of the bronchioles and enable respiratory gas exchange. © Virtual Medical Centre
Pulmonary alveolus - 1 Photo