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Upper Gastrointestinal Surgery - part 2

Những tế bào này rất nhiều nhiều hơn nữa trong môn vị hơn so với các vùng tim và oxyntic mặc dù khi so sánh với các tế bào niêm mạc họ vẫn còn tương đối ít về số lượng. Với kính hiển vi ánh sáng, họ đã được gọi là tế bào enterochromaffin. | 30 2 UPPER GASTROINTESTINAL SURGERY 3. Neuroendocrine cells. These cells are much more numerous in the pyloric than in the cardiac and oxyntic zones although when compared with the mucous cells they are still relatively few in number. With light microscopy they have been called enterochromaffin cells. With electron microscopy their cytoplasmic granules are clearly visible after staining with chromium or silver salts. On the basis of their staining reactions the cells have been divided into two types argentaffin cells in which the granules reduce silver without pretreatment and argyrophilic cells in which a reducing substance is required before the granules will react with silver. The mucosal zones of the stomach are not sharply defined the glands of one region mingle with those of the adjoining region and intermediate glands may be present between the mucosal zones. Physiology Gastric Secretions The cells of the gastric glands secrete about 2500 ml of gastric juice daily. This contains a variety of substances and gastric enzymes whose role is to kill ingested bacteria aid protein digestion stimulate the flow of bilary and pancreatic juices and provide the necessary pH for pepsin to begin protein degradation Table 2.3 . Mucus Secretion The most abundant epithelial cells are mucussecreting columnar cells which cover the entire luminal surface and extend down into the glands as mucous neck cells . These cells secrete bicarbonate-rich mucus that coats and lubricates the gastric surface and serves an Table 2.3. Contents of normal fasting gastric juice Cations Na K Mg2 H Anions Cl- HPO42- SO42- Pepsins I-III Gelatinase Mucus Intrinsic factor Water important role in protecting the epithelium from acid and other chemical insults. It is made up of glycoprotein subunits bound by disulphide bonds and forms a water-insoluble gel that is impermeable to H ions. Production is stimulated by luminal acid and vagal activity and is increased by prostaglandins. Therefore aspirin .