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.
Little pockets in the lung called alveoli fill with the air and the oxygen diffuses into capillaries. This oxygenated blood then goes back to the heart where it is pumped around to the rest of the body. When it reaches capillary beds in our tissues the oxygen diffuses out into the tissues. ...Read more.