In general, there are three stages leading from iron deficiency to anemia: 1  First, there is an insufficient supply of iron, which causes iron stores in the bone marrow to be depleted. This stage generally has no symptoms. 2  Second, iron deficiencies develop and begin to affect hemoglobin production.
Surfactant immune function is primarily attributed to two proteins: SP-A and SP-D. These proteins can bind to sugars on the surface of pathogens and thereby opsonize them for uptake by phagocytes. It also regulates inflammatory responses and interacts with the adaptive immune response.
Surfactant prevents this collapse by reducing the surface tension of the fluids that line the lungs and helping to equalize the pressures between large and small air spaces. Surface tension is a measure of the attraction molecules of a fluid have for each other.f the surface tension is lowered, the attraction among molecules of the fluid is decreased and the surface area of the fluid increases. For example, if a drop of detergent is added to a drop of water, the detergent reduces the surface tension and the drop of water flattens out.