Nutrition Science and Everyday Application - beta v 0.1

262 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
Figure 5.9. A phospholipid molecule consists of a polar phosphate “head,” which is hydrophilic,
and a non-polar lipid “tail,” which is hydrophobic.
The amphiphilic nature of phospholipids makes them very useful for several functions in
the body. Every cell in the body is encased in a membrane composed primarily of a double
layer of phospholipids (also known as the phospholipid bilayer), which protects the inside of
the cell from the outside environment while at the same time allowing for transport of fat
and water through the membrane. Phospholipids also play a role in transporting fats in the
blood, as we’ll learn later in this unit.