 Dear students, in this topic we shall discuss the control of slivary and gastric secretions in detail. The slivary gland continues a slow flow of sliva in the absence of food. Sliva's production is not completely closed. But when food is not present, it keeps on secreting sliva slowly. However, presence of food in the mouth stimulates extra secretion. Food stimulates sliva secretion in such a way that it stimulates the cholinergic parasympathetic nerves present in the slivary glands. As a result, they increase secretion of the slivary glands. In addition, cognitive awareness of food also results in rapid secretion of sliva. Now we shall discuss the gastric secretions. Gastric glands in the wall of stomach secrete gastric juice. This gastric juice contains three major components. Hydrochloric acid, pepsin and mucus. Three different types of cells produce these ingredients separately. The parietal or auxintic cells of gastric glands secrete hydrochloric acid. While the goblet cells synthesize and secrete mucus. Whereas the chief cells secrete pepsin in an inactive form, pepsinogen. Now we shall discuss how the secretion of gastric juice is controlled. In mammals, the gastric secretion occurs in three phases. Which have separate controls. These phases are sapphic phase, gastric phase and intestinal phase. In the sapphic phase, gastric secretion occurs in response to sight, smell and taste of food. It also occurs in response to conditioned reflexes. That is why this phase is mediated by the brain. And this stimulation is blocked by vegas nerve. If the smell of food and taste of food is good, then gastric juice will start producing more. Because the brain will be mediated. If this is not happening, then vegas nerve will be stimulated and it will block the secretion of gastric juice. The gastric phase is mediated by the action of gastric hormone and histamine. It also involves direct stimulation of the wall of the stomach due to the presence of food in stomach. Food stimulates the chemoreceptors and mechanoreceptors present in the wall of the stomach. Other than this, gastric juice secretion increases the secretion of gastric juice. The third phase is the intestinal phase of gastric secretion. It is more complex phase. It is controlled by many hormones. For example, gastrine, secretion, vasoactive, intestinal, peptide and gastric inhibitory peptide. All these modulate, either stimulate or inhibit the secretion of gastric juice in the stomach. This phase starts when a chyme rich in proteins enters the duodenum. After leaving the stomach, when the chyme enters the duodenal part of the intestine, the gastric juice secretion starts. Because all the food does not enter the duodenum. Most of the protein part of the food is still present in the stomach. Therefore, the gastric juice secretion can be enhanced. If the chyme enters the duodenum and it has high quantity of proteins in it, then the wall of the duodenum is stimulated to secret enteric gastrine. This gastric secretion acts on the stomach, gastric glands and stimulates their rate of secretion. If a chyme is rich in fats and sugars enters the duodenum, then mucosa of the duodenum secretes gastric inhibitory peptide. Gastric inhibitory peptide inhibits gastric secretion in the stomach.