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.
The determinants of tissue oxygenation are illustrated in Figure 13.1. The oxygen supply to tissues is shown as the rate of O2 uptake from the microcirculation (i.e., VO2). The metabolic requirement for oxygen (MRO2) is the rate at which oxygen is metabolized to water in the mitochondria.eonardo da Vinci, 1500. Despite good intentions, much of what we do to patients in the name of aerobic support is without documented need or documented benefit. This is a reflection of the inability to obtain a direct measurement of tissue oxygen tensions.