Surfactant proteins are essential components of the pulmonary surfactant, a mixture of lipids and proteins that reduces surface tension in the lungs. They play a crucial role in maintaining lung stability and preventing alveolar collapse during breathing. There are four main surfactant proteins, designated as SP-A, SP-B, SP-C, and SP-D, each with specific functions in surfactant metabolism and immune response. These proteins are produced by type II alveolar cells in the lungs and are vital for proper respiratory function. Deficiencies or abnormalities in surfactant proteins can lead to respiratory disorders, such as neonatal respiratory distress syndrome and other lung diseases.