Question

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we know that oxynotic cells secrets and synthesise Hydrochloric acid, So will we call it the enzyme ?
Similarly Goblet cells secrets mucus , is it too an enzyme ?

please answer only if you know , On Monday I have my exam !!!

Answer 1

First, the mucosa doesn't get digested as it secretes the HCl because the pH within the parietal cells remains near neutrality by the following mechanism (note that all parts of the mechanism take place simultaneously): (1) Potassium ions, K+, diffuse passively from the parietal cell into the lumen. (2) An active transport pump brings K+ back into the parietal cell, simultaneously secreting H+ from the cell to the lumen. As much K+ returns by this route as leaks in (1). (3) Chloride ions, Cl-, diffuse passively from the cell to the lumen, and their negative charges balance the positive charges of the secreted H+.(4) An exchanger on the opposite face of the parietal cell balances this loss of Cl- by importing Cl - from the blood in exchange for bicarbonate ions (HCO3-). (5) Within the cell, water reacts with carbon dioxide (CO2) to form carbonic acid (H2CO3), which dissociates into H+ and HCO3-. The figure (right) summarizes these steps. In summary, the secreted HCl arises from H+ (from water) and Cl- from the blood. Both accumulate only in the lumen and not in the parietal cell.