Fig. 9. A comparison of the summation of total measured osmolytes in the blood plasma and the fluid phases of stomach-1 (cardiac stomach), stomach-2 (pyloric stomach) and intestine prior to feeding (A) and at 20 h post-feeding (B). Arrows indicate measured osmolalities. (A) Prior to feeding, note the reasonable agreement between total measured osmolytes and measured osmolality in blood plasma, stomach-1 and stomach-2, but not in intestine. (B) After feeding, note continued agreement in blood plasma, but the discrepancies in all three gastrointestinal fluids. Note also the different contributions of urea versus Na⁺+Cl^– in the various compartments.