What are Pleural membranes? Describe their structure and function in respiration?
In human anatomy, the pleural cavity is the body cavity that surrounds the lungs. The pleura is a serous membrane which folds back upon itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, viz. blood vessels, bronchi and nerves. The pleural cavity, with its associated pleurae, aids optimal functioning of the lungs during respiration. The pleural cavity also contains pleural fluid, which allows the pleurae to slide effortlessly against each other during ventilation. Surface tension of the pleural fluid also leads to close apposition of the lung surfaces with the chest wall. This physical relationship allows for optimal inflation of the alveoli during respiration. The pleural cavity transmits movements of the chest wall