Respiratory physiology: Pulmonary surfactant

Physiology · Respiratory physiology

Surfactant is a mixture of phospholipids, carbohydrates and proteins released by type 2 pneumocytes. The main functioning component is dipalmitoyl phosphatidylcholine (DPPC) which reduces alveolar surface tension.

Basics

first detectable around 28 weeks
as alveoli decrease in size, surfactant concentration is increased, helping prevent the alveoli from collapsing
reduces the muscular force needed to expand the lungs (i.e. decreases the work of breathing)
lowers the elastic recoil at low lung volumes and thus helps to prevent the alveoli from collapsing at the end of each expiration