Pulmonary Surfactant. The force of surface tension in the lungs is so great that without something to reduce the surface tension, the airways would collapse after exhalation, making re-inflation during inhalation much more difficult and less effective. Collapse of the lungs is called alectasis.
Rules for Using Semicolons. A semicolon is most commonly used to link (in a single sentence) two independent clauses that are closely related in thought. When a semicolon is used to join two or more ideas (parts) in a sentence, those ideas are then given equal position or rank. Some people write with a word processor; others write with a pen or pencil. Use a semicolon between two independent clauses that are connected by conjunctive adverbs or transitional phrases.
A sentence can be extended with a semicolon when a slight break is preferable to a new sentence. (You cannot do the same thing with a comma. Merge Two Sentences with a Semicolon. On occasion, a writer may decide that the next sentence is so closely connected to the previous one that a slight break is more appropriate than a new sentence. A semicolon can be used for this purpose. No one was seriously hurt in the accident; one man suffered a broken finger.