A close up of an eye showing the capillaries. The definition of a capillary is a small blood vessel that is part of the network of the small arteries and small veins, or an extremely thin tube through which nothing thicker than a human hair can pass.
Phospholipid bilayer. Definition. noun. The two layers of phospholipids arranged in such a way that their hydrophobic tails are projecting inwards while their polar head groups are projecting on the outside surfaces. Supplement. This arrangement of phospholipids in bilayer is used to describe the cell membranes of many animal and plant cells. The two layers of phospholipids are arranged in a way that their hydrophobic tails are projecting to the interior whereas their hydrophilic heads are projecting the exterior.
Phospholipids form the basic structure of a cell membrane, called the lipid bilayer. Scattered in the lipid bilayer are cholesterol molecules, which help to keep the membrane fluid consistent. Membrane proteins are important for transporting substances across the cell membrane.hospholipids make up the basic structure of a cell membrane. A single phospholipid molecule has two different ends: a head and a tail. The head end contains a phosphate group and is hydrophilic. This means that it likes or is attracted to water molecules.