Stomach

Lecture Objectives
By the end of this lecture, students are expected to: compare in histological structure of glands present in three regions of stomach.
1. List and describe the absorptive cells in along the GIT
2. Outline the different types of cells within gastric glands and link this difference to functional
3. Relate the functional to diagnostic histological feature of three regions of small intestine
4. Summarize the diagnostic histological feature of three regions of large intestine
5. Summarize the distribution the enteroendocrine cells in gastrointestinal tract
Stomach
The stomach is a “J”-shaped sac (hollow) organ, The stomach is a greatly dilated segment of the digestive tract
whose main functions are:
? To continue the digestion of carbohydrates initiated by the amylase of saliva,
? To add an acidic fluid to the ingested food and mixing its contents into a viscous mass called chyme by the churning activity of the muscularis,
? To begin digestion of triglycerides by a secreted lipase.
? To promote the initial digestion of proteins with the enzyme pepsin.
The stomach can be divided into the cardia, fundus, body, and pylorus, The much larger fundus and body regions are identical in microscopic structure and are the sites of gastric glands releasing acidic gastric juice. The mucosa and submucosa of the empty stomach have large, longitudinally directed folds called rugae, which flatten when the stomach fills with food.
Figure.1:shows the simple columnar epithelium, gastric pit and gastric gland
Dr.Hameda abdulmahdi College of Medicine /Dep. of anatomy
& histology 2nd stage
2
1. The cardiac region connects to the lower esophagus at the esophagogastric junction, which is characterized by a change from the nonkeratinized stratified squamous epithelium of the esophagus to the simple columnar epithelium of the stomach. A thickened smooth muscle ring called the gastroesophageal sphincter (lower esophageal sphincter) or cardiac sphincter surrounds the opening at the junction of the lower esophagus and cardiac region of the stomach, this smooth muscle contracts to prevent the acidic stomach contents from entering the esophagus. The glands in the lamina propria of the cardia are called cardiac glands and are branched tubular glands with coiled secretory portions. The cardiac gland contains mainly mucus-secreting cells The cardiac gland contains mainly mucus-secreting cells and some stem cells, enteroendocrine cells, and, occasionally, parietal cells. The mucus-secreting cells mainly produce mucus and lysozymes. The mucus protects the stomach wall from acidic gastric juices; lysozymes destroy bacterial membranes, preventing bacterial infections .