What is the role of surfactant in the lungs?

Answer 1

Answer

Surfactant reduces surface tension, so that the alveoli in the lungs are able to expand. It is essentially a biological detergent.

Surfactant reduces surface tension. Without surfactant, the wet surfaces of the alveoli in your lungs would stick together and your lungs would not be able to expand - so, you would not be able to breath. The alveoli are the tiny sacs in your lungs where oxygen is captured from inhaled air and absorbed into your bloodstream. They are very small and are have moist surfaces. Wet surfaces stick together due to surface tension, which is caused by the attraction that water has for itself. To demonstrate how strong surface tension is, take two small glass panes, wet them slightly and press them together until there is no air between them. Now try to pull them apart. It's extremely difficult (you usually have to slide them apart because they will not separate otherwise). However, if you mix dish detergent in the water first, it will be much easier to pull them apart, because the detergent is a surfactant - a substance which combines with water and by doing so reduces the surface tension of the water.

About three to four weeks before birth, you lungs begin to produce surfactant. When you are born and take your first breath, you have to open the fluid-filled alveoli to allow air in. Without surfactant, this would be nearly impossible, which is which very premature infants have so much difficulty breathing. These very early preemies are given surfactant (either artificial or derived from calf lungs) down a tube going to their lungs, to help their alveoli open and allow air entry.

Some medical conditions cause loss of surfactant. In pulmonary edema, fluid from the blood invades and floods the alveoli. Among other problems, this causes dilution and washout of the surfactant, so that alveoli are more likely to collapse. Inflammation of the lungs also causes reduced surfactant production, so again the alveoli collapse due to increased surfaced tension. In cystic fibrosis, excess mucus production displaces the surfactant (and mucus has an even higher surface tension than water). Patients with CF are given extra surfactant to make up for this loss and to provide enough surfactant that it can act on the mucus as well as the normal alveolar fluid.

Answer 2

Surfactant is a product which is secreted by the lungs. Its purpose is to reduce the lungs surface tension. Without surfactant the moist surfaces of the lungs would have such a high surface tension that the smaller alveoli would collapse.

Answer 3

lipid , surface tension lowering agent . secreted from type 2 alveolar epithelium . composed of phospholipids ( lecithin ), apoproteins & calcium ions .

Answer 4

Alveolar cells