Aspartame is the most controversial food additive in history, and its approval for use in food was the most contested in FDA history. In the end, the artificial sweetener was approved, not on scientific grounds, but rather because of strong political and financial pressure.
The arterioles then divide further into capillaries. Capillaries are the smallest blood vessels and their walls are only one cell thick which allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuses through the capillary walls into the tissues that need it. This is aided by the relatively high blood pressure that also squeezes the oxygen and nutrients through the capillary wall and into the cells of the tissue.
1 Capillaries. 2  These are small, thin blood vessels that connect the arteries and the veins. 3  Their thin walls allow oxygen, nutrients, carbon dioxide, and other waste products to pass to and from our organ's cells.n addition to carrying fresh oxygen from the lungs and nutrients to the body's tissues, it also takes the body's waste products, including carbon dioxide, away from the tissues. This is necessary to sustain life and promote the health of all parts of the body. There are three main types of blood vessels: 1  Arteries.