What triggers the gastric phase of gastric secretion?
Gastric secretion is stimulated chiefly by three chemicals: acetylcholine (ACh), histamine, and gastrin. Below pH of 2, stomach acid inhibits the parietal cells and G cells; this is a negative feedback loop that winds down the gastric phase as the need for pepsin and HCl declines.
What stimulates the secretion of gastric acid?
The three stimulants of gastric acid secretion likely to have physiological roles in regulation of secretion are acetylcholine, gastrin, and histamine. Acetylcholine is released by vagal and intramucosal reflex stimulation, acting directly on the parietal cell.
What are the phases of gastric acid secretion?
However, once gastric secretion begins, all three phases can occur simultaneously. Gastric secretion occurs in three phases: cephalic, gastric, and intestinal. During each phase, the secretion of gastric juice can be stimulated or inhibited.
Which phase of gastric secretion is stimulated quizlet?
During the cephalic phase of gastric secretion, increased production of gastric juice occurs. the intestinal reflex inhibits gastric emptying.
What is gastric acid secretion?
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.
What are the three phases of gastric secretion quizlet?
Name the 3 steps? Cephalic phase, Gastric phase, Intestinal phase.
What controls gastric juice secretion?
Gastric acid secretion is under nervous and hormonal control. Gastrin, the major circulating stimulus of acid secretion, probably does not stimulate the parietal cells directly but acts to mobilize histamine from the ECL cells in the oxyntic mucosa. Histamine stimulates the parietal cells to secrete HCl.
What is gastric secretion?
The digestive secretions of the gastric glands in the stomach, consisting mainly of pepsin, hydrochloric acid, rennin, and mucin. ( NCI Thesaurus)
Which of the three phases of gastric acid secretion is stimulated by the distention of the stomach?
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. Gastric secretion of acid and pepsinogen follows stimulation of the oral and gastric vagal afferents.
Does the intestinal phase stimulate gastric secretion or inhibit it quizlet?
What stimulates the enteroendocrine G cells to produce gastrin?
What are the 3 phases of gastric secretions?
The physiologic stimulation of acid secretion has classically been divided into three interrelated phases: cephalic, gastric, and intestinal [6]. The cephalic phase is activated by the thought, taste, smell, and sight of food, and swallowing. It is mediated mostly by cholinergic/vagal mechanisms.
What are the 3 phases of gastric function?
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.
When does the reflex phase of gastric secretion take place?
The cephalic phase (reflex phase) of gastric secretion, which is relatively brief, takes place before food enters the stomach. The smell, taste, sight, or thought of food triggers this phase.
How is the gastric phase of the body triggered?
2. The “gastric phase” is triggered by distension. The direct effect of food entering the stomach is to cause a marked fall in gastric [H+]. This is because the food buffers the pre-existing H+ ions so pH initially rises.
What causes the secretion of gastric acid in the stomach?
Vago-vagal reflexes, local enteric reflexes, triggered by distension and the gastrin mechanism, cause secretion of gastric acid during the time food remains in the stomach.
What is the role of the duodenum in gastric secretion?
The intestinal phase of gastric secretion has both excitatory and inhibitory elements. The duodenum has a major role in regulating the stomach and its emptying. When partially digested food fills the duodenum, intestinal mucosal cells release a hormone called intestinal (enteric) gastrin, which further excites gastric juice secretion.
