Blood-tissue exchange

Goresky CA, Rose CP. Blood-tissue exchange in liver and heart the influence of heterogeneity of capillary transit times. Fed Proc 1977 36 2629-34. 

Bassingthwaighte JB, Wang CY, Chan IS. Blood-tissue exchange via transport and transformation by capillary endothelial cells. Circ Res 1989 65 997-1020. 

Figure 8.2 Cylindrical geometry of the Krogh-Erlang model of blood-tissue exchange. The upper panel, from Middleman [141], illustrates the assumed parallel arrangement of capillaries with each vessel independently supplying a surrounding cylinder of tissue. A diagram of the model geometry is provided in the lower panel. Figure in upper panel is reprinted with the permission of John Wiley Sons, Inc.

Before examining how a model of the level of detail of the four-region model illustrated in Figure 8.6 is constructed, we first examine the two-region model analyzed in 1953 by Sangren and Sheppard [178], This model will allow us to explore the kinetics of blood-tissue exchange based on an analytically tractable set of governing equations. 

Axially distributed models of blood-tissue exchange... 

FIG. 1. Schematic representation of a five-region, axially distributed blood-tissue exchange model composed of plasma (p), endothelial cells (ec), interstitial fluid space (isf), mucosal cells (me), and the intestinal lumen (i). Convection (F) takes place in both the plasma and intestinal lumen. The Ps are volumes of distribution. Barrier conductances are given by peimeability-surfiace area products (P5). Reactions or metabolic consumption within the cells are given by the clearances (G). 

A Blood-Tissue Exchange Model with Carrier-Mediated Transport... 

FIG. 8. Schematic representation of a Ave-re on, axially distributed blood-tissue exchange mode with carrier-mediated transport on the membranes of the mucosal cell. See the legend to Fig. 1 for an explanation of symbols. 

Dash, R. K., and J. B. Bassingthwaighte. 2006. Simultaneous blood-tissue exchange of oxygen, carbon dioxide, bicarbonate, and hydrogen bon, Ann Biomed Eng, 34,1129-1148. 

Urine, blood, tissues Add acetone centrifuge extract on ion exchange column derivatize with diazopentane cleanup on silica gel if needed (metabolites) GC/FPD 40-150 pg/L (40-150 ppb) 36-97 EPA1980d Lores and Bradway 1977... 

Part II of this book represents the bulk of the material on the analysis and modeling of biochemical systems. Concepts covered include biochemical reaction kinetics and kinetics of enzyme-mediated reactions simulation and analysis of biochemical systems including non-equilibrium open systems, metabolic networks, and phosphorylation cascades transport processes including membrane transport and electrophysiological systems. Part III covers the specialized topics of spatially distributed transport modeling and blood-tissue solute exchange, constraint-based analysis of large-scale biochemical networks, protein-protein interactions, and stochastic systems. 

One-dimensional advection will be used in Chapter 8 as a component in models of cellular biochemical systems that are coupled to blood-tissue solute exchange. 

Figure 1. A simple model illustrating some of the complex interactions involved in zinc absorption and metabolism. Following absorption, a fraction of the zinc goes directly into blood, another fraction passes first through the portal circulation and then into the systemic circulation. Some zinc is resecreted into the gastrointestinal tract, thereby becoming available for reabsorption. Activity in blood can exchange with tissue pools, be excreted in urine, or secreted back into the gastrointestinal tract.

Figure 3. Schematic diagram of the blood-gas exchanges in tissue (15)...

Weinbaum-Jiji Bioheat Equation. Since 1980, researchers (Chen and Holmes, 1980 Chato, 1980 Weinbaum et al., 1984) have begun to question the validity of the Pennes bioheat equation. Later, Weinbaum and Jiji (1985) developed a new equation for microvascular blood tissue heat transfer, based on the anatomic analysis (Weinbaum et 1984), that illustrated that the predominant mode of heat transfer in the tissue was the countercurrent heat exchange between a thermally significant artery and vein pair. The near-perfect countercurrent heat exchange mechanism implies that most of the heat leaving the artery is transferred to its countercurrent vein rather than released to the sur-... 

Phosphorus. Eighty-five percent of the phosphoms, the second most abundant element in the human body, is located in bones and teeth (24,35). Whereas there is constant exchange of calcium and phosphoms between bones and blood, there is very Httle turnover in teeth (25). The Ca P ratio in bones is constant at about 2 1. Every tissue and cell contains phosphoms, generally as a salt or ester of mono-, di-, or tribasic phosphoric acid, as phosphoHpids, or as phosphorylated sugars (24). Phosphoms is involved in a large number and wide variety of metaboHc functions. Examples are carbohydrate metaboHsm (36,37), adenosine triphosphate (ATP) from fatty acid metaboHsm (38), and oxidative phosphorylation (36,39). Common food sources rich in phosphoms are Hsted in Table 5 (see also Phosphorus compounds). 

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