A Midwestern Doctor
Within the conventional biomedical model, water is thought of as a uniform, evenly mixed (homogeneous) substance that exists as an aqueous solution that facilitates the random mixing of chemical reactants necessary to produce the biochemistry of life. Homogeneity is assumed to occur within any contained water compartment (e.g. inside a cell, inside the blood stream, inside the gallbladder), because with this assumption, water takes a passive role and thus, greatly simplifies the process of modeling complex biological processes.
However, when you dig into this, you often find water and fluid systems (e.g., blood) are anything but homogeneous. The previously mentioned Russian researchers, for example, made an excellent case that blood traveling through blood vessels in a vortexing motion concentrates its components into the center of its vortex (thereby reducing their drag on the periphery of the blood vessels). and that different compositions of blood concentrate in different parts of the body.
… Classically, we believe that cells are liquid bags whose contents are dictated by proteins on the membrane of the cells (e.g., the sodium-potassium pump that concentrates potassium inside the cell). However, since microscopes were first developed, an alternative worldview also was developed that indicates that the water inside cells is very different and alternates between behaving in a gel-like fashion and behaving like a normal liquid.