Modeling of oxygen diffusion from the blood vessels to intracellular organelles.

We describe recent models of oxygen transport in tissue along the pathway from the hemoglobin molecule to the mitochondria and illustrate their applications. Microvasculature is the major site of exchange between blood and parenchymal cells for gases (O2, CO2, CO, NO), nutrients, metabolic products, and drugs. These exchange processes are affected by the architecture of the microvessels and the surrounding cells; distribution of blood flow; transport characteristics of blood, cells, and interstitial space; and rates of various chemical reactions associated with the transport processes. These processes operate at multiple levels of biological organization, from the molecular to the organ levels. Quantitative understanding of molecular transport in cells and tissues, specifically of oxygen transport, is the prerequisite for understanding the mechanisms of many diseases and for designing effective therapies. Mathematical and computational models provide a powerful set of tools for studies of these complex phenomena.