Presentation on theme: "Department of Histology and Embryology"— Presentation transcript:
1 Department of Histology and Embryology Digestive SystemDepartment of Histology and EmbryologyZhang Xi-Mei
2 What is the Digestion?Digestion is the process by which food and drink are broken down into their smallest parts so that the body can use them to build and nourish cells and to provide energy.Digestion begins in the mouth when we chew and swallow, and is completed in the large intestine.
17 Mucous neck cellsa. They are present between parietal cells in the necks of gastric glands.b. They can secrete mucous. They are difficult to distinguish from chief cells in plain H&E stained section.
18 Chief cellsa. In the lower region of tubular glands, and have the characteristics of protein-synthesizing cells.b. The granules in their cytoplasm contain the inactive enzyme pepsinogen.pepsinogenpepsinH+Chief cellParietal cellDiagram of a chief cell
19 Parietal cellsa. Rounded or pyramidal cells, intensely eosinophilic cytoplasm.Resting---tubulovesicles---few microvilli.Activity---canaliculus---more microvilli.b. Parietal cells secrete HCl and Intrinsic factor.Diagram of a parietal cell
20 Enteroendocrine cells Stem cellsa. Found in neck regions.b.These cells have a high rate of mitosis: some of them move upward to replace the pit and surface mucous cells, other cells migrate more deeply into the glands and differentiate into parietal, chief cells and etc.Enteroendocrine cellsIn base of gastric glands.
21 Small intestine A. Basic anatomy duodenum, jejunum, ileum Structure of small intestinePlicae circulares, villi, and microvilli increase the absorptive surface area of small intestine.
27 Mucosa 1. The epithelium of intestine villi 2. Intestinal glands 3. Five types of cells in intestinal glandsAbsorptive cellsGoblet cellsPaneth’s cellsEndocrine cellsStem cells
28 1. Absorptive cells Tall columnar, an oval nucleus in the basal half of the cell,striated border at the apex.MicrovilliIncreasing the areaAbsorptionThe function of the columnar absorptive cell is the absorption of water, minerals, amino acids, simple sugars, and lipid.
29 2. Goblet cells Interspersed between the absorptive cells. duodenum increasingjejunumileumGoblet cell secretion of mucin .The mucus lubricates and forms a barrier which protects the mucosal epithelium from potentially noxious intraluminal substances.
30 3. Paneth’s cellsOccur in small groups at the base of the intestinal glands.They have both large eosinophilic secretory granules.They secrete lysozyme.
31 Large intestineThe mucosa does differ from that of the small intestine in several aspects: 1. There are no villi. 2. The intestinal glands are larger, more numerous and more densely packed. 3. Numerous goblet cells. 4. There are no Paneth’s cells.
32 Appendix Small, narrow, and irregular lumen. Abundant lymphoid nodules.Fewer and shorter intestinal glands.
33 Homework Describe the structure of the stomach fundus gland. Describe the cell type of the small intestine gland.Describe the structure of intestinal villi.What prevents the proteolytic enzymes and low pH from damaging the stomach?