Water and Solute Movement Between the Lateral Spaces and Villous Capillaries Is Subject to the Same Forces That Govern Water and Solute Movement Between the Extracellular and Vascular Fluids in Other Tissues

Water and all other nutrients, whether they are absorbed through the Iranscellular or paracellular routes, enter the extracellular fluid of the lateral spaces before entering the vascular system. Therefore the movement of extracellular fluid components into capillaries is of particular importance to intestinal absorption. The physical laws determining the distribution of water between the intravascular and extra- vascular fluid are the same in the villi as in other tissues. These Starling laws (which can be reviewed in Chapters 1 and 23) simply stale that the movement of water is determined by the algebraic sum of osmotic and hydrostatic (created by water pressure) forces.