The phospholipids are made up of two distinct regions which are the head and the tail regions. The arrangement of the phospholipids molecules makes up the lipid bi layer. The head region is made up of the phoshpate molecules and is polar in nature. The phospholipids molecules are arranged in such a way that, the polar heads are exposed on both sides of the cell in contact with water while the non polar tails are buried in the interior of the membrane.