Molecules passing through cell membrane, illustration 插畫檔

Illustration of small molecules passing through the phospholipid bilayer that forms the the cell membrane. The phospholipid molecules line up in two sheets, with the hydrophilic tails projecting inward and their polar head groups projecting outwards. The hydrophilic surface on both sides of the membrane is the point of contact for molecules leaving or entering the cell. Small molecules, compact enough to cross the cell membrane's lipid bilayer are able to move through the barrier and in and out of the cell