The normal concentrations of the major cations (Na , K ) and the major anions (Cl , HCO ) in gastrointestinal secretions are summarised in table 2. As shown in the table each fluid should be compared to plasma.
Saliva differs from plasma in that it is quite dilute and has a high K concentration.
Gastric juice is similar to plasma except that the Na content is reduced so that protons may be secreted. In addition there is no HCO .
Pancreatic juice differs from plasma in having a large HCO concentration. Due to the high HCO the other anion Cl is reduced so that the total count of the anions approximates that of the cations.
Bile is similar to plasma except that there is a slightly higher HCO concentration.