Surface Tension Injury Essay

The lung wall is delicate which makes it susceptible to surface tension injury. The wall is made of epithelium, which is tissue that lines the cavities and surfaces of organs in the body. When complications with infections occur regions of the lung can fill with fluid, also babies born premature can have underdeveloped lungs causing increased surface tension. These cause the lungs to remain closed, a disease called respiratory distress syndrome. The deformation of biological cells when exposed to different flow conditions is a problem. Surface tension on an air–liquid boundary creates liquid flows, which causes the lung to close due to the formation of a liquid plug because of the drainage of the liquid lining coating the airways. Once closed, by a plug or a larger collapse of the lung, it must be reopened. For example, people with acute lung injury cannot breathe on their own due to the collapse and fluid blockage of pulmonary airways. These patients are placed on ventilators to survive, but this creates microbubbles in the flow that can cause more injury to the lungs. …show more content…
In extended regions of airway closure, analyses have predicted the existence of gradients in shear and normal stress that may cause a pinching effect on epithelial cells. Short regions of closure can occur wherein a liquid plug obstructs the airway. Figure 1 Example of pinching effect
Studies indicate that microbubble or liquid plug flow creates a combination of normal and shear stresses to the epithelial on airway walls. Experiments in in vitro systems demonstrates that these flows can cause injury from mechanical stresses on airway epithelial cells. These stresses may cause cell deformation, membrane rupture, and cell detachment. These stresses can also cause biological responses such as inflammation, which can increase the fluid in the lungs. Figure 2 Stresses on epithelium