• Clinical science

Stomach

Summary

The stomach is a hollow intraperitoneal organ in the left upper quadrant of the abdomen, between the esophagus and the duodenum in the gastrointestinal tract. It is supplied with arterial blood from the celiac trunk and its branches. The veins of the stomach drain into the portal vein, and the lymphatics eventually drain into the celiac lymph nodes. It is innervated by the sympathetic and parasympathetic nervous system, as well as the myenteric plexus and submucous plexus of the enteric nervous system. The stomach has four histological layers: the mucosa, submucosa, muscularis propria, and serosa. The mucosa is lined with numerous glands containing specialized cells that produce various secretions: e.g., parietal cells, which secrete gastric acid and intrinsic factor, and gastric chief cells, which secrete pepsinogen. Acetylcholine (ACh), gastrin, and histamine are the main stimulators of gastric secretions. Somatostatin, cholecystokinin (CCK), secretin, and gastric inhibitory peptide (GIP) are the main inhibitors.

Gross anatomy

Overview [1]

Anatomical parts

The antrum and lower lesser curvature are the most common sites for peptic stomach ulcers.

Peritoneal attachments

The stomach is an intraperitoneal organ.

Vasculature, lymphatics, and innervation of the stomach [1]

Arteries
Structure Origin Important features
Lesser curvature Superior part
Inferior part
Greater curvature Superior part
Inferior part
  • Gastroduodenal artery (a branch of the common hepatic artery)
Fundus
  • Contained within the gastrosplenic ligament
Posterior gastric wall
Veins
Names Drainage into Important feature
Stomach
Lymphatic vessels
Names Drainage into
Stomach
Innervation
Name Effects
Autonomic nervous system Sympathetic
  • ↓ Glandular secretion
  • Peristalsis
  • ↑ Sphincter tone
Parasympathetic
  • ↑ Glandular secretion
  • Peristalsis
  • ↓ Sphincter tone (i.e., sphincter relaxation)
Enteric nervous system
  • Controls local gastrointestinal secretion and nutrient absorption
  • Controls inherent myogenic motility of the GIT

Esophageal varices develop in portal hypertension due to the portosystemic shunting of blood from the left gastric vein (portal system) into the esophageal veins (caval system).

Microscopic anatomy

  • The stomach's four histological layers are the same as the layers of the gastrointestinal tract.
  • The mucosa of the stomach is specialized in the following ways:
    • It contains millions of gastric pits that are lined by mucous-secreting cells (foveolar cells) and open into ; one or more gastric glands.
    • Gastric glands in the lamina propria contain; various specialized cells and vary; in composition and thickness depending on their location in the stomach.
    • Stem cells ; located at the necks of the gastric glands proliferate and differentiate to replace gastric cells.
    • Enteroendocrine cells ; are located throughout ; the gastric mucosa and secrete various secretory and regulatory products of the gastrointestinal tract.
Specialized cells of the gastric glands
Region Cell type Secretory product or function
Fundus and body
  • Ghrelin [2]
Pylorus and antrum
  • G cells
  • Gastrin

Function

Types of digestion

Mechanism of gastric acid secretion

Gastric acid contains high amounts of hydrochloric acid (HCl). Repeated vomiting can therefore cause metabolic alkalosis due to the loss of acid (H+).

Phases of gastric acid secretion [3]

Phase Stimuli Main mediators Effect on acid secretion Mechanism Effect on gastric pH
Cephalic phase
  • Thought, smell, and taste of food
  • Increase in acid secretion
  • Decreases
Gastric phase
  • Distention of the stomach by food
  • Increase in acid secretion
  • Increases
  • Food buffers gastric acid → ↑ gastric pH
Intestinal phase
  • Decrease in acid secretion
  • Decreases
  • Food moves into the duodenum → buffering of acid by food decreases → ↓ gastric pH to basal levels

Disturbances of gastric secretions

References:[4][2]

Embryology

Clinical significance

  • 1. Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences; 2016.
  • 2. Liddle RA. Ghrelin. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/ghrelin. Last updated July 7, 2017. Accessed November 24, 2018.
  • 3. Vakil BN. Physiology of gastric acid secretion. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/physiology-of-gastric-acid-secretion. Last updated September 24, 2018. Accessed January 30, 2019.
  • 4. Olszewski PK, Li D, Grace MK, Billington CJ, Kotz CM, Levine AS. Neural basis of orexigenic effects of ghrelin acting within lateral hypothalamus. Peptides. 2003; 24(4): pp. 597–602. pmid: 12860204.
last updated 04/22/2020
{{uncollapseSections(['VwcG3e0', 'jtc_WV0', 'dwco3e0', '4tc3dV0', 'qFcCQV0', 'ktcmdV0'])}}