The First Breath

When a newborn baby takes the first breath it uses a force 15-20 times the normal force of inhalation to inflate the lungs.The elastic tissue is stretched permanently and the lung surfactants made of phospholipid and hydrophilic and hydrophobic proteins stop the alveoli from collapsing as the baby exhales.The cells of the alveoli secrete a lipoprotein complex. The proteins and lipids that comprise surfactant have both a hydrophilic region and a hydrophobic region.By adsorbing to the air-water interface of alveoli with the hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of surfactant reduces surface tension during elastic recoil.