What is back diffusion of hydrogen ions?
The back diffusion of hydrogen ion into the normal and abnormal human gastric mucosa was determined by (1) comparing the acid secretion of the stimulated mucosa with and without a glycine buffer solution in the stomach, and (2) measuring hydrogen, sodium, potassium, and chloride fluxes following the instillation of an …
What is acid back diffusion?
The loss of acid from the gastric contents increases when the mucosa is exposed to certain drugs or is diseased, giving rise to the suggestion that the increased degree of “back-diffusion” of acid indicates mucosal damage, reflecting a breakdown of the gastric mucosal “barrier” to back-diffusion of acid from the …
What is the mechanism of H+ secretion by gastric parietal cells?
The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl.
What specific type of transport mechanism is involved in the control of acid secretion in the stomach?
Gastric acid secretion is regulated by an intricate interplay of neural (acetylcholine), hormonal (gastrin), and paracrine (histamine, somatostatin) mechanisms. Receptors for each of these agents and the signal transduction pathways to which these receptors are coupled have been identified on the parietal cell.
What does gastric acid secretion mean?
Acid is secreted by parietal cells in the proximal two thirds (body) of the stomach. Gastric acid aids digestion by creating the optimal pH for pepsin and gastric lipase and by stimulating pancreatic bicarbonate secretion.
When hydrogen ions pass from the parietal cell into the duct of the gastric gland they are exchanged for which ion?
hydrogen ions and chloride ions join in the duct of the gastric gland. In the parietal cell, carbonic acid dissociates into a bicarbonate ion and a hydrogen ion.
What stimulates acid secretion from parietal cells?
Gastrin secreted from G cells binds directly on parietal cells or stimulates acid secretion mediated by histamine release from ECL cells.
What is the source of hydrogen ions used to form stomach acid?
Hydrogen ions are generated within the parietal cell from dissociation of water. The hydroxyl ions formed in this process rapidly combine with carbon dioxide to form bicarbonate ion, a reaction cataylzed by carbonic anhydrase. Bicarbonate is transported out of the basolateral membrane in exchange for chloride.
What are the 3 phases of gastric secretion?
The process of gastric secretion can be divided into three phases (cephalic, gastric, and intestinal) that depend upon the primary mechanisms that cause the gastric mucosa to secrete gastric juice.
What is the mechanism of gastric secretion?
Gastric secretion is stimulated by the act of eating (cephalic phase) and the arrival of food in the stomach (gastric phase). Arrival of the food in the intestine also controls gastric secretion (intestinal phase). The secreted fluid contains hydrochloric acid, pepsinogen, intrinsic factor, bicarbonate, and mucus.
What are the three phases of gastric activity?
Which substances would cause stimulation of gastric HCl secretion when applied to parietal cells?
The presence of amino acids in the small intestine stimulates secretion of gastrin, which in turn stimulates HCl secretion by parietal cells.