Title: Gastrointestinal physiology
Content:  with a low pH of 1. H+ is pumped into the stomach by exchanging it with K+. This process also requires ATP as a source of energy; however, Cl− then follows the positive charge in the H+ through an open apical channel protein. HCO3− secretion occurs to neutralize the acid secretions that make their way into the duodenum of the small intestine. Most of the HCO3− comes from pancreatic acinar cells in the form of NaHCO3 in an aqueous solution. This is the result of the high concentration of both HCO3− and Na+ present in the duct creating an osmotic gradient to which the water follows.
Title: Gastric acid
Content:  relatively pH-neutral gastric mucus layer. Chloride and sodium ions are secreted actively from the cytoplasm of the parietal cell into the lumen of the canaliculus. This creates a negative potential of between &minus;40and&minus;70mV across the parietal cell membrane that causes potassium ions and a small number of sodium ions to diffuse from the cytoplasm into the parietal cell canaliculi. The enzyme carbonic anhydrase catalyses the reaction between carbon dioxide and water to form carbonic acid. This acid immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ions leave the cell through H+/K+ ATPase antiporter pumps. At the same time, sodium ions are actively reabsorbed. This means that the majority of secreted K+ and Na+ ions return to 
Title: Hypokalemia
Content:  secretes into the lumen of the collecting duct of a nephron. In addition, when H+ is expelled from the cell (by H+ATP-ase), cations—in this case potassium—are taken up by the cell in order to maintain electroneutrality (but not through direct exchange as with the H+-K+ATPase). In order to correct the pH during alkalosis, these cells will use these mechanisms to reabsorb great amounts of H+, which will concomitantly increase their intracellular concentrations of potassium. This concentration gradient drives potassium to be secreted across the apical surface of the cell into the tubular lumen through potassium channels (this facilitated diffusion occurs in both Type B intercalated cells and Principal cells in the collecting 
Title: Parietal cell
Content:  Parietal cells (also known as oxyntic cells) are epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and body regions of the stomach. They contain an extensive secretory network of canaliculi from which the HCl is secreted by active transport into the stomach. The enzyme hydrogen potassium ATPase (H+/K+ ATPase) is unique to the parietal cells and transports the H+ against a concentration gradient of about 3 million to 1, which is the steepest ion gradient formed in the human body. Parietal cells are primarily regulated via histamine, acetylcholine and gastrin signalling from both central and local modulators.
Title: CLCN5
Content:  cortical and medullary thick ascending limb of Henle’s loop. Proximal tubular cells (PTCs) are the main site of ClC-5 expression. By means of the receptor-mediated endocytosis process, they uptake albumin and low-molecular-weight proteins freely passed through the glomerular filter. ClC-5 is located in early endosomes of PTCs where it co-localizes with the electrogenic vacuolar H+‐ATPase (V‐ATPase). ClC-5 in this compartment contributes to the maintenance of intra-endosomal acidic pH. Environment acidification is necessary for the dissociation of ligand from its receptor. The receptor is then recycled to the apical membrane, while ligand is transported to the late endosome and lysosome where it is degraded. ClC-5 supports efficient acidification 
Title: Parietal cell
Content:  the transport of H+/K+ ATPase from the cytoplasm to the cell membrane. This causes resorption of K+ ions and secretion of H+ ions. The pH of the secreted fluid can fall by 0.8. Gastrin primarily induces acid-secretion indirectly, increasing histamine synthesis in ECL cells, which in turn signal parietal cells via histamine release/H2 stimulation. Gastrin itself has no effect on the maximum histamine-stimulated gastric acid secretion. The effect of histamine, acetylcholine and gastrin is synergistic, that is, effect of two simultaneously is more than additive of effect of the two individually. It helps in non-linear increase of secretion with stimuli physiologically.
Title: Gastrointestinal physiology
Content:  The largest component of secreted fluids is ions and water, which are first secreted and then reabsorbed along the tract. The ions secreted primarily consist of H+, K+, Cl−, HCO3− and Na+. Water follows the movement of these ions. The GI tract accomplishes this ion pumping using a system of proteins that are capable of active transport, facilitated diffusion and open channel ion movement. The arrangement of these proteins on the apical and basolateral sides of the epithelium determines the net movement of ions and water in the tract. H+ and Cl− are secreted by the parietal cells into the lumen of the stomach creating acidic 
Title: Gastric acid
Content:  amounts of bicarbonate and secretes bicarbonate through the pancreatic duct to the duodenum to neutralize gastric acid passing into the digestive tract. The active components of gastric acid are protons and chloride. Often simplistically described as hydrochloric acid, these species are produced by parietal cells in the gastric glands in the stomach. The secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the "hydrochloric acid" is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen, a level maintained by the proton 
Title: Eccrine sweat gland
Content:  The secretion of eccrine glands is a sterile, dilute electrolyte solution with primary components of bicarbonate, potassium, and sodium chloride (NaCl), and other minor components such as glucose, pyruvate, lactate, cytokines, immunoglobulins, antimicrobial peptides (e.g., dermcidin), and many others. Relative to the plasma and extracellular fluid, the concentration of Na+ ions is much lower in sweat (~40 mM in sweat versus ~150 mM in plasma and extracellular fluid). Initially, within the eccrine glands, sweat has a high concentration of Na+ ions. The Na+ ions are re-absorbed into the tissue via the epithelial sodium channels (ENaC) that are located on the apical membrane of the cells that form the eccrine gland ducts (see Fig. 9 and Fig. 10 of the reference). This 
Title: Parietal cell
Content: Hydrogen ions are formed from the dissociation of carbonic acid. Water is a very minor source of hydrogen ions in comparison to carbonic acid. Carbonic acid is formed from carbon dioxide and water by carbonic anhydrase. ; The bicarbonate ion (HCO3−) is exchanged for a chloride ion (Cl−) on the basal side of the cell and the bicarbonate diffuses into the venous blood, leading to an alkaline tide phenomenon. ; Potassium (K+) and chloride (Cl−) ions diffuse into the canaliculi. ; Hydrogen ions are pumped out of the cell into the canaliculi in exchange for potassium ions, via the H+/K+ ATPase. These pumps are increased in number on luminal side by 

Question: the site of secretion of h+ and cl-?
Answer: Parietal cells.