2 also called pulmonary surfactant. one of certain lipoproteins that reduce the surface tension of pulmonary fluids, allowing the exchange of gases in the alveoli of the lungs and contributing to the elasticity of pulmonary tissue.or 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. In the lungs, surfactant reduces the surface tension and helps to maximize the surface area available for gas exchange.
The First Day of Summer 2016 (Summer Solstice) is on Monday, June 20. The First Day of Summer 2017 (Summer Solstice) is on Wednesday, June 21. The First Day of Summer 2018 (Summer Solstice) is on Thursday, June 21. The First Day of Summer 2019 (Summer Solstice) is on Friday, June 21. The First Day of Summer 2020 (Summer Solstice) is on Saturday, June 20.
Washington's Birthday. Winter. In the United States and the rest of the northern hemisphere, the first day of the spring season is the day of the year when the Sun crosses the celestial equator moving northward (on March 20 th or 21 st). This day is known as the Vernal Equinox.