There Are Three Major Mechanisms of Chloride Absorption
One mechanism of chloride absorption is coupled sodium chloride absorption, as discussed previously in relation to sodium (Figure 30-18, A). Another mechanism is paracellular chloride absorption, which occurs in association with sodium co-transport of glucose and amino acids (Figure 30-18, B).
Paracellular chloride transport occurs because of an electrical gradient. Sodium co-transport leads to the net movement of positive electrical charges (Naf) across the apical membrane, because neither glucose nor most amino acids are charged molecules. As the sodium cations are transferred to the lateral spaces, the spaces develop a positive polarity with respect to the gut lumen. Chloride from the gut lumen passes directly into the lateral spaces through the tight junctions because these junctions are readily permeable to small anions. This provides a major mechanism for the absorption of CΓ while maintaining electrical neutrality, although a small electrical potential is maintained across the gut surface, the lumen being negative with respect to the lateral spaces.The last mechanism of chloride absorption is by direct exchange for bicarbonate (Figure 30-18, C) without coupled sodium absorption. With this mechanism, there is a net movement Ofbicarbonate into the gut lumen, resulting in an increase in luminal pH. This can be particularly important in the colon of large herbivores where large concentrations of fermentation acids are created and require buffering.
More on the topic There Are Three Major Mechanisms of Chloride Absorption:
-
Veterinarian -