Kõht

In Estonian, Kõht literally means the stomach. In anatomy, the stomach is a sac-like organ of the digestive system located in the upper abdomen between the esophagus and the small intestine.

Anatomy: It consists of four regions—cardia, fundus, body, and antrum—leading to the pyloric canal and pyloric sphincter that regulates emptying into the duodenum. The stomach's inner surface forms rugae, which flatten as it expands.

Histology: The mucosa contains simple columnar epithelium with gastric glands. Parietal (oxyntic) cells secrete hydrochloric acid and intrinsic factor; chief (peptic) cells secrete pepsinogen; mucous cells protect the lining; enteroendocrine cells release gastrin, histamine, and other hormones.

Function: The acidic environment denatures proteins, activates pepsinogen to pepsin, initiates protein digestion, and forms a semifluid chyme. The mucus-bicarbonate barrier protects mucosa; some absorption occurs, but most nutrients are absorbed later in the small intestine. Intrinsic factor is required for vitamin B12 absorption.

Regulation and motility: Gastric secretion is regulated by neural (vagus and enteric nerves) and hormonal factors. Gastrin stimulates acid secretion; histamine from enterochromaffin-like cells amplifies it; acetylcholine from vagal nerves stimulates parietal cells. Somatostatin inhibits secretion. The pyloric sphincter controls chyme release, slowing gastric emptying when needed.

Clinical notes: Ulcers and gastritis can arise from Helicobacter pylori infection or nonsteroidal anti-inflammatory drug use; pernicious anemia results from lack of intrinsic factor; gastric cancers, while less common than colorectal cancers, occur and are linked to H. pylori infection and other risk factors.