stomach

Examples of stomach in the following topics:

• Gross Anatomy of the Stomach

  • The stomach is divided into four sections, each of which has different cells and functions.
  • Lying beneath the stomach is the pancreas.
  • The gastric glands begin secreting before food enters the stomach due to the parasympathetic impulses of the vagus nerve, that also make the stomach a storage vat for that acid.
  • The cardiac region, where the contents of the esophagus empty into the stomach.
  • This diagram of the stomach shows the cardiac region, fundus, body, and pylorus.

• Microscopic Anatomy of the Stomach

  • Like the other parts of the gastrointestinal tract, the stomach walls are made of a number of layers.
  • The epithelium of the stomach forms deep pits, called fundic or oxyntic glands.
  • The secretion of pepsinogen prevents self-digestion of the stomach cells.
  • Near the top of the pits, closest to the contents of the stomach, there are mucus-producing cells called goblet cells that help protect the stomach from self-digestion.
  • A micrograph that shows a cross section of the stomach wall, in the body portion of the stomach.

• Cephalic Phase

  • The cephalic phase of gastric secretion occurs even before food enters the stomach via neurological signals.
  • Cephalic phase causes ECL cells to secrete histamine and increase HCl acid in the stomach.
  • The cerebral cortex sends messages to hypothalamus, the medulla, and the parasympathetic nervous system via the vagus nerve, and to the stomach (gastric glands in walls of fundus and body of stomach).
  • When food enters stomach, the stomach stretches and activates stretch receptors.
  • Receptors send message to the medulla, and then back to the stomach via the vagus nerve.

• Digestive Properties of the Stomach

  • It also causes increased motility (movement, peristalsis) in the stomach.
  • Other than gastrin, these hormones all act to turn off the stomach's action.
  • The stomach can taste sodium glutamate using glutamate receptors.
  • The fundic gland, found in the stomach, secretes gastrin and other hormones.
  • The cardiac gland, found in the stomach, secretes gastrin and other hormones.

• Gastric Phase

  • The gastric phase is a period in which swallowed food activates gastric activity in the stomach.
  • Ingested food stimulates gastric activity in two ways: by stretching the stomach and by raising the pH of its contents.
  • Small peptides also buffer stomach acid so the pH does not fall excessively low.
  • But as digestion continues and these peptides are emptied from the stomach, the pH drops lower and lower.
  • The stomach stretches and churns while enzymes break down proteins.

• Esophagus

  • The esophagus is a muscular tube that moves food from the pharynx to the stomach via peristalsis.
  • Food then moves down the esophageal tube through waves of muscle movement, or peristalsis, until it reaches the stomach.
  • The esophagus is an organ in vertebrates that consists of a muscular tube through which food passes from the pharynx to the stomach.
  • In humans the esophagus is continuous with the laryngeal part of the pharynx within the neck, and it passes through the thorax diaphragm and into abdomen to reach the cardiac orifice of the stomach.
  • In much of the gastrointestinal tract, smooth muscles contract in sequence to produce a peristaltic wave which forces a ball of food (called a bolus) from the pharynx to the stomach.

• Gastroesophageal Reflux Disease

  • Gastroesophageal reflux disease (GERD) is chronic mucosal damage caused by stomach acid coming up from the stomach into the esophagus.
  • Gastroesophageal reflux disease (GERD), gastro-oesophageal reflux disease (GORD), gastric reflux disease, or acid reflux disease is chronic mucosal damage caused by stomach acid coming up from the stomach into the esophagus.
  • In healthy patients, the Angle of His—the angle at which the esophagus enters the stomach—creates a valve that prevents duodenal bile, enzymes, and stomach acid from traveling back into the esophagus where they can cause burning and inflammation of sensitive esophageal tissue.
  • Visceroptosis or Glénard syndrome, in which the stomach has sunk in the abdomen upsetting the motility and acid secretion of the stomach
  • The patient receives a radiocontrast die, often injected into the stomach.

• 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.
  • That is, the duodenum sends inhibitory signals to the stomach by way of the enteric nervous system, while also sending signals to the medulla that inhibit the vagal nuclei.
  • This reduces vagal stimulation of the stomach and stimulates sympathetic neurons, which send inhibitory signals to the stomach.
  • Originally called gastric-inhibitory peptide, it is no longer thought to have a significant effect on the stomach.

• Organs of the Digestive System

  • Next the bolus reaches the stomach itself.
  • The stomach is a muscular, hollow bag that is an important part of the upper GI tract.
  • Many organisms have a variety of stomach types, with many segments or even multiple stomachs.
  • As humans, we have only one stomach.
  • This snaking tube is made up of three parts, in order from the stomach:

• 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.
  • Gastric inhibitory peptide (GIP) is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach.
  • Ghrelin is a hormone that is released by the stomach and targets the pituitary, signaling to the body that it needs to eat.