What is phospholipid？

Phospholipids are lipids that contain phosphoric acid.
There are two main classes of phospholipids in the body, phospholipids made of glycerol are called glycerophospholipids. And phospholipid made of sphingomanol is called sphingomyelin (SM).
Phospholipids are amphoteric molecules. One end is a hydrophilic head containing nitrogen or phosphorus. The other end is a long hydrophobic (oleophilic) hydrocarbon chain.
For this reason, the hydrophilic and hydrophobic ends of phospholipids are close to each other, often forming lipid bilayer, the structure of cell membrane, together with other molecules such as proteins, glycolipids and cholesterol. The cell membrane of human body consists of about 40% protein and about 50% lipid (phospholipid mainly). Phospholipid, as an important component of human cells, plays an important role in maintaining metabolism, balancing hormones and enhancing immunity.