gastric juice

Examples of gastric juice in the following topics:

• Cephalic Phase

  • The cephalic phase of gastric secretion occurs even before food enters the stomach via neurological signals.
  • The cephalic phase of gastric secretion occurs even before food enters the stomach, especially while it is being eaten.
  • Neurogenic signals that initiate the cephalic phase of gastric secretion originate from the cerebral cortex, and in the appetite centers of the amygdala and hypothalamus.
  • This phase of secretion normally accounts for about 20 percent of the gastric secretion associated with eating a meal.
  • 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.

• Processes and Functions of the Digestive System

  • Pancreatic juices are excreted into the digestive system to break down complex molecules such as proteins and fats.
  • Once the bolus reaches the stomach, gastric juices mix with the partially digested food and continue the breakdown process.
  • The stomach is a muscular bag that maneuvers food particles, mixing highly acidic gastric juice and powerful digestive enzymes with the chyme to prepare for nutrient absorption in the small intestine.
  • Stimulatory hormones such as gastrin and motillin help the stomach pump gastric juice and move chyme.

• Gross Anatomy of the Stomach

  • A mucous membrane lines the stomach which contains glands (with chief cells) that secrete gastric juices.
  • The gastric glands begin secreting before food enters the stomach due to the parasympathetic impulses of the vagus nerve, making the stomach also a storage vat for that acid.
  • The arteries supplying the stomach are the left gastric, the right gastric and right gastroepiploic branches of the hepatic, and the left gastroepiploic and short gastric branches of the lineal.
  • The arteries break up at the base of the gastric tubules into a plexus of fine capillaries, which run upward between the tubules.

• Pancreatic Juice

  • Pancreatic fluid or juice contains digestive enzymes that pass to the small intestine where they help to further break down the carbohydrates, proteins, and lipids (fats) in the chyme.
  • Pancreatic juice is alkaline in nature due to the high concentration of bicarbonate ions.
  • This is useful in neutralizing the acidic gastric acid, allowing for effective enzymic action.
  • Pancreatic juice secretion is regulated by the hormones secretin and cholecystokinin.
  • Pancreatic duct rupture and pancreatic juice leakage cause pancreatic self-digestion.

• Digestive Properties of the Stomach

  • Gastric ulcers can be healed by supplemental daily doses of Epidermal growth factor (EGF).
  • Cholecystokinin (CCK) primarily effects the gall bladder, causing it to contract, but it also decreases gastric emptying and increases release of pancreatic juice, which is alkaline and neutralizes the chyme.
  • Gastric inhibitory peptide (GIP) decreases both gastric acid release and motility.
  • Enteroglucagon decreases both gastric acid and motility.
  • There are many different gastric glands which secrete many different chemicals.

• Gastric Phase

  • The gastric phase is a period in which swallowed food activates gastric activity in the stomach.
  • The gastric phase is a period in which swallowed food and semidigested protein (peptides and amino acids) activate gastric activity.
  • About two-thirds of gastric secretion occurs during this phase .
  • Histamine is a paracrine secretion from the enteroendocrine cells in the gastric glands.
  • During the gastric phase, gastrin is secreted.

• Mucosa

  • Food, mucous, and digestive juices pass through the lumen, and the mucosa comes in direct contact with digested food (chyme).
  • In the stomach the epithelium is simple columnar, and is organized into gastric pits and glands to deal with secretion.

• Types of Cells in the Pancreas

  • It is also a digestive, exocrine, organ, secreting pancreatic juice containing digestive enzymes that assist with digestion and the absorption of nutrients in the small intestine.
  • Amylin slows gastric emptying, preventing spikes in blood glucose levels.

• Intestinal Phase

  • The intestinal phase occurs in the duodenum, responds to arriving chyme, and moderates gastric activity via hormones and nervous reflexes.
  • The intestinal phase is the stage of digestion in which the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes.
  • The duodenum initially enhances gastric secretion, but soon inhibits it.
  • These hormones primarily stimulate the pancreas and gall bladder, but they also suppress gastric secretion and motility.
  • Originally called gastric-inhibitory peptide, it is no longer thought to have a significant effect on the stomach.

• Peptic Ulcer Disease

  • Rarely, an ulcer can lead to a gastric or duodenal perforation, which leads to acute peritonitis.
  • The gastric mucosa protects itself from gastric acid with a layer of mucus, the secretion of which is stimulated by certain prostaglandins.
  • Younger patients with ulcer-like symptoms are often treated with antacids.The ability of antacids to neutralize acidity by increasing the pH or blocking the secretion of acid by gastric cells is critical in reducing acidity in the stomach.
  • This gastric ulcer was found in tissue removed during a gastrectomy.
  • This endoscopic image shows a gastric ulcer, which upon biopsy was shown to be gastric cancer.