gastrin

Examples of gastrin in the following topics:

• Gastric Phase

  • Gastric secretion is stimulated chiefly by three chemicals: acetylcholine (ACh), histamine, and gastrin.
  • Gastrin is a hormone produced by enteroendocrine G cells in the pyloric glands.
  • The chief cells secrete pepsinogen in response to gastrin and especially Ach, and ACh also stimulates mucus secretion.
  • As dietary protein is digested, it breaks down into smaller peptides and amino acids, which directly stimulate the G cells to secrete even more gastrin: a positive feedback loop that accelerates protein digestion.
  • During the gastric phase, gastrin is secreted.

• Digestive Properties of the Stomach

  • The hormone gastrin causes an increase in the secretion of HCl from the parietal cells, and pepsinogen from chief cells in the stomach.
  • Other than gastrin, these hormones all act to turn off the stomach's action.
  • The pyloric gland, found in the stomach, secretes gastrin and other hormones.
  • The cardiac gland, found in the stomach, secretes gastrin and other hormones.
  • The fundic gland, found in the stomach, secretes gastrin and other hormones.

• Intestinal Phase

  • Stretching of the duodenum accentuates vagal reflexes that stimulate the stomach, and peptides and amino acids in the chyme stimulate G cells of the duodenum to secrete more gastrin, which further stimulates the stomach.
  • The effect of this is that gastrin secretion declines and the pyloric sphincter contracts tightly to limit the admission of more chyme into the duodenum.

• Hormones of the Digestive System

  • Gastrin is in the stomach and stimulates the gastric glands to secrete pepsinogen (an inactive form of the enzyme pepsin) and hydrochloric acid.
  • Secretion of gastrin is stimulated by food arriving in the stomach.

• Cephalic Phase

  • There will also be an influence on G cells to increase gastrin circulation.
  • Chemical stimuli (i.e., partially digested proteins, caffeine) directly activate G-cells (enteroendocrine cells) located in the pyloric region of the stomach to secrete gastrin; this in turn stimulates gastric glands to secrete gastric juice.

• Gastrointestinal Reflex Pathways

  • When this reflex is stimulated, the release of gastrin from G-cells in the antrum of the stomach is shut off.
  • These hormones fall into three major categories: the gastrin family, the secretin family, and a third family composed of the remaining hormones that fit into neither of the these two families.

• Hormonal Responses to Food

  • During the gastric phase, the hormone gastrin is secreted by G cells in the stomach in response to the presence of proteins.
  • Gastrin stimulates the release of stomach acid, or hydrochloric acid (HCl), which aids in the digestion of the majority of proteins.

• Other Hormone-Producing Structures

  • Gastrin - is in the stomach and stimulates the gastric glands to secrete pepsinogen (an inactive form of the enzyme pepsin) and hydrochloric acid.
  • Secretion of gastrin is stimulated by food arriving in stomach.

• Peptic Ulcer Disease

  • Thus, the bacterium can cause a chronic active gastritis, resulting in a defect in the regulation of gastrin production by that part of the stomach.
  • Gastrin secretion can either be increased, or as in most cases, decreased, resulting in a too basic or too acidic stomach environment, respectively.

• Gastroesophageal Reflux Disease

  • Zollinger-Ellison syndrome, which can be present with increased gastric acidity due to gastrin production.