He lungs are surrounded by two membranes, the pleurae. The outer pleura is attached to the chest wall and is known as the Parietal pleura; the inner one is attached to the lung and other visceral tissues and is known as the Visceral pleura. In between the two is a thin space known as the pleural cavity or pleural space. It is filled with pleural fluid, a serous fluid produced by the pleura.
The pleural fluid lubricates the pleural surfaces and allows the layers of pleura to slide against each other easily during respiration. It also provides the surface tension that keeps the lung surface in contact with the chest wall. During quiet breathing, the cavity normally experiences a negative pressure (compared to the atmosphere) which helps adhere the lungs to the chest wall, so that movements of the chest wall during breathing are coupled closely to movements of the lungs.
The pleural membrane also helps to keep the two lungs away from each other and air tight, thus if one lung is punctured and collapses due to an accident, the other pleural cavity will still be air tight, and the other lung will work normally
The parietal pleura is highly sensitive to pain; the visceral pleura is not. The visceral pleura has a dual blood supply, from the bronchial and pulmonary arteries. In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax (see below), the other hemi thorax will still be able to function normally.
The pleural fluid lubricates the pleural surfaces and allows the layers of pleura to slide against each other easily during respiration. It also provides the surface tension that keeps the lung surface in contact with the chest wall. During quiet breathing, the cavity normally experiences a negative pressure (compared to the atmosphere) which helps adhere the lungs to the chest wall, so that movements of the chest wall during breathing are coupled closely to movements of the lungs.
The pleural membrane also helps to keep the two lungs away from each other and air tight, thus if one lung is punctured and collapses due to an accident, the other pleural cavity will still be air tight, and the other lung will work normally
The parietal pleura is highly sensitive to pain; the visceral pleura is not. The visceral pleura has a dual blood supply, from the bronchial and pulmonary arteries. In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax (see below), the other hemi thorax will still be able to function normally.