Site of action of gastro-oesophageal reflux treatments. Top a stomach with the esophagus and duodenum seen in section. Zoom a section of the gastric mucosa of the body of the stomach. There are gastric glands. The gastric gland consists of three parts: the crypt, dilated area lined with superficial mucous cells secreting mucus, the collar followed by the body. Three types of cells line the body: parietal cells (large pink cell), main cells (mauve) enteroendocrine cells (small pink cell). The parietal cells secrete gastric juice (green balls). A lower right window shows a parietal cell releasing gastric juice and K + (blue square) and H + (red square) ions by the proton pump, under the influence of histamine (black balls) attaching to the receptor H2 on the vascular pole of the parietal cell. This excess of K + / H + ions is responsible for the acidity.