Mucosa of stomach

At a glance

English

Mucosa of stomach

Latin (TA2)

Tunica mucosa gastris

System

Digestive

Region

Abdomen

Side

Single, on the midline

About the mucosa of stomach

The gastric mucosa is the innermost layer of the stomach wall, lying on the submucosa and the thick muscle coat outside it. In life it is soft and velvety, pinkish towards the pylorus and a deeper red over the rest of the organ. It is thinnest near the cardia and thickest near the pylorus. When the stomach is empty and contracted, the mucosa with its submucosa is thrown into long folds, the gastric rugae, running mostly lengthways; they flatten out as the stomach fills.

The surface is divided into small raised gastric areas by shallow grooves, and is dotted with millions of pits. Each gastric pit opens onto the surface and receives several tubular glands below. The whole surface and the pits are lined by a single layer of tall columnar cells that make a thick, alkaline mucus. Beneath lies the lamina propria, a loose connective tissue holding the glands, and then a thin layer of smooth muscle, the muscularis mucosae, which can help squeeze secretions out of the glands. At the cardia the mucosa meets the squamous lining of the oesophagus at an irregular line; at the pylorus it meets the duodenal lining.

Glands differ by region. In the fundus and body, the gastric glands proper contain parietal cells, the source of hydrochloric acid and intrinsic factor, chief cells, which secrete pepsinogen, and mucous neck cells. Near the cardia and in the pyloric region the glands are mostly mucous; the pyloric glands also contain G cells, which release the hormone gastrin to boost acid output. Scattered endocrine cells make other signalling substances.

The mucus layer and bicarbonate secretion protect the lining from its own acid. When that defence fails, for example with Helicobacter pylori infection or anti-inflammatory drugs, the lining becomes inflamed (gastritis) or breaks down into a peptic ulcer. Loss of parietal cells in autoimmune gastritis stops intrinsic factor production, so vitamin B12 is not absorbed and pernicious anaemia follows. The rapid turnover of surface cells also allows quick healing of small injuries.

Function and supply

Function

Secretes acid, pepsinogen, intrinsic factor, mucus and hormones such as gastrin, and protects the stomach wall from its own secretions.

Nerve supply

Secretion is stimulated by the vagus nerves and the enteric (submucosal) plexus, and modified by sympathetic fibres from the coeliac plexus.

Blood supply

A dense capillary network fed by the gastric arteries through the submucosa: the left and right gastric, right and left gastro-omental and short gastric arteries.