So cholesterol is an extremely important component of the cell membrane. The polar hydroxyl groups of our cholesterol basically interact with the hydrophilic polar heads and the rest of the cholesterol molecule, which is basically a hydrocarbon backbone. The nonpolar region basically extends throughout the entire section of our cell membrane like this integral protein. And so we see that by adding cholesterol into our cell membrane we basically control the fluidity of our cell membrane. By adding cholesterol, we decrease the fluidity because we basically allow we pack these hydrophobic and hydrophilic sections closer together. So we can imagine that by placing this wall we call the cholesterol into our cell membrane.