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.
One major role of phospholipids in cells is to form membranes. Membranes in cells are phospholipid bilayers, which are barriers that prevent charged particles and large molecules from moving across them. The outer skin of the cell is a phospholipid bilayer.Eukaryotic cells also have skin surrounding defined organelles with different functions inside them.embranes in cells are phospholipid bilayers, which are barriers that prevent charged particles and large molecules from moving across them. The outer skin of the cell is a phospholipid bilayer. Eukaryotic cells also have skin surrounding defined organelles with different functions inside them.