Stomach

Abstract

Gross anatomy

Overview

Regions of the stomach

  • Cardia
    • Located below the diaphragm
    • Originates at the z-line
    • Forms the gastroesophageal junction
  • Fundus
    • Formed by the upper curvature of the stomach
  • Body (stomach)
  • Antrum
    • Connects the body and pylorus of the stomach
  • Pylorus
    • Connects to the duodenum
    • Divided into pylorus antrum and pyloric canal
    • Contains the pyloric sphincter:
      • Contraction prevents passage of chyme into the duodenum
        • Contraction is stimulated by secretin, CCK, and GIP

Omentum

Vasculature

  • The blood supply of the stomach arises from the celiac artery (trunk).
    • From the anterior surface of the aorta, at the level of T12-L1
    • Travels along the superior border of the pancreas

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

Microscopic anatomy

Gastric cells and secretory products

Gastric secretions

The gastric secretory response is divided into 3 phases

1. Cephalic phase: Mediated by vagal (cholinergic) mechanisms, which get activated by sight, smell, and taste of food as well as swallowing.

2. Gastric phase: Mediated by gastrin, which is released in response to gastric distension and chemical stimulation (amino acids).

3. Intestinal phase: Occurs in response to entry of acidic chyme into the duodenum, feedback regulatory hormones, such as somatostatin from D cells, decrease acid secretion.

Gastric acid

Overview of secretions

Cell type Function Control
Intrinsic factor
  • Binds to Vitamin B12
  • Required for absorption in the terminal ileum
Gastric acid
  • Decreases stomach pH
  • Activates pepsinogen to pepsin
Pepsin
  • Secreted as pepsinogen
  • Activated by acidic gastric pH (H+)
  • Protein digestion
  • Inactivated by high pH
Bicarbonate
  • Mucosal cells
  • Secretin
Gastrin
Ghrelin
  • Stomach
  • Stimulation
    • Fasting
    • Sleep deprivation
  • Inhibition
    • Intake of food (stretching of stomach)

Disturbances of stomach secretions

Diseases of the stomach

Embryology

See the section on embryology in overview of the gastrointestinal tract.

  • 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.
  • 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.
last updated 11/24/2018
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