Mucociliary apparatus is the key feature of the upper and lower respiratory tracks and it includes mucous producing glands of the nasal epithelium as well as ciliated cells, one of its primary function is to shield the airways with hazardous substances, it does so by creating a layer of mucous that catches unwanted material and move them into posterior pharynx where they can be removed by sneezing splitting, swallowing or blowing
Pleural cavity is the body cavity that contains the lungs. The lungs are surrounded by two serous membranes, the pleurae. The outer pleura (parietal pleura) covers and is attached to the chest wall. The inner pleura (visceral pleura) covers and is attached to the lung and other structures, i.e. blood vessels, bronchi and nerves. The thin space between the two pleura is known as the pleural space; it normally contains a small amount of pleural fluid.Pleural fluid serves several functions. It lubricates the pleural surfaces, thus allowing the pleural layers to slide easily against each other during ventilation. The surface tension resulting from the presence of the pleural fluid keeps the lung surfaces in close apposition to the chest wall. This allows for optimal inflation of the alveoli during respiration. It also directly transmits pressures from the chest wall to the visceral pleural surface (and hence, the lung). In this manner, movements of the chest wall, particularly during heavy breathing, are coupled to movements of the lungs.
The thoracic cavity is enclosed by the thoracic cage or ribs and the diaphram, the two lungs occupy the majority of the cavity, Most of work of breathing is accomplished by diaphragm, which separates the thoracic and abdominal cavities it is wide and dump shaped muscle that works with Intercostal muscles which is located between the ribs to expand and contract the chest the are both internal and external Intercostal muscles with the internal muscle positioned near the lungs surrounded by the external muscles
