I think it's specifically made in RBCs. Carbonic anhydride catalyze the conversion of CO2 to H2CO3 inside RBCs. Then the H2CO3 gets deprotonated to HCO3, bicarbonate.So bicarbonates are secreted by pancreas, but where in the body is bicarbonate made? Is it also made in the pancreas?
Ah, so gallbladder also secretes bicarbonate?Any cell that carries the enzyme Carbonic Anhydrase, you should expect bicarbonate to be present in a significant amount. RBC's are jam packed with them as they play a crucial role in maintaining constant blood pH, as does certain cells in the nephron of the kidney, which are responsible for sereting excess H+ into the nephron tubule to be excreted. The lower ductal cells of the pancreas and gallbladder also pump bicarbonate with their secretions to help neutralize the acidic chyme entering the small intestines; this also facilitates the optimal pH for various pancreatic enzymes to function.
Both have cells lining the ducts, each cell with specific antiporters that pump bicarbonate out and chloride in, both down their concentration gradients. Those cells also have the enzyme carbonic anhydrase, so they are made by those ductal cells, not elsewhere.Ah, so gallbladder also secretes bicarbonate?
So when pancreas and gallbladder secrete bicarbonate to small intestine, are they secreting bicarbonate that was made in their own cells, or are they simply COLLECTING bicarbonate that was made in other parts of the body (as you said, mainly from RBC) and then pumping it to the small intestine, or are they doing both?