Fig. 7.
Model for diffusional shunting between inflow and outflow in a spatially distributed system. The space in the fold, with exchange rate constant Ps, in the region across which diffusional shunting occurs; this shunting produces concentration gradients throughout the tissue at all times, preventing equilibration. A numerical scheme for computing solutions is indicated above: positions along the capillary axis from x = 0 to x = L are represented by segments 1 to N. There are M capillaries in the folded slab. While the exchange is greatest between the upstream and downstream halves of the Mth capillary, there is also diffusion in all directions which means that the first segment of the first segment of the first capillary (segment 1.1) also changes with its last segment (1, N), but indirectly.