Surfactant proteins are essential components of the lung surfactant system, which helps reduce surface tension in the alveoli, the tiny air sacs in the lungs. These proteins play a crucial role in maintaining proper lung function and preventing the collapse of alveoli during breathing. There are several types of surfactant proteins, including SP-A, SP-B, SP-C, and SP-D, each with specific functions in surfactant metabolism and immune defense. In addition to their role in lung function, surfactant proteins are involved in the body's immune response. They help to recognize and clear pathogens, contributing to the overall health of the respiratory system. Deficiencies or abnormalities in surfactant proteins can lead to respiratory disorders, such as neonatal respiratory distress syndrome.