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.
Oxygen is transported by your red blood cells to all the organs and tissues of your body. This happens in the alveoli, which are the final branchings of your lungs, where oxygen diffuses through the alveolar epithelium into your alveolar capillaries, according to the Johns Hopkins School of Medicine.