Presentation on theme: "Hassall's corpuscles are a unique and characteristic feature of:"— Presentation transcript:
1 Hassall's corpuscles are a unique and characteristic feature of: (A) spleen.(B) thymus.(C) lymph nodes.(D) bone marrow.(E) tonsils.
2 Lymphatic nodules are found in: (A) cortex of lymph nodes(B) tonsils(C) spleen(D) respiratory and gastrointestinal mucosa.(E) all of the above
3 Which of the following statements concerning epithelial reticular cells of the thymus is FALSE ? (A) They are supporting cells.(B) They are not located in the thymic medulla.(C) They have long processes.(D) They assist in forming the blood-thymus barrier.
4 Department of Histology and Embryology Digestive SystemDepartment of Histology and EmbryologyYu Hongwei
5 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 small intestine.
6 Digestive Systemoral cavity, esophagus, stomach, small and large intestines, rectum, and anus.Digestive tract:small gland: fundis gland, small intestinal glandlarge gland: salivary gland, pancreas, liverDigestive glands:
16 3.Taste budFigure. showing the taste cells and the taste pore. The drawing also illustrates several cell types (basal, taste, and supporting) and afferent nerve fibers that, upon stimulation, will transmit the sensory information to the central gustatory neurons.
17 Taste budThese are clustered in taste buds. Each taste bud has a pore that opens out to the surface of the tongue enabling molecules and ions taken into the mouth.
18 There are five primary taste sensations: salty sour sweet bitter Taste budThere are five primary taste sensations:saltysoursweetbitterUmami is the response to salts of glutamic acid,a flavor enhancer used in many processed meats and cheeses.
21 Source: parotid, submandibular, sublingual salivary glands FunctionsProduce saliva, to wet and lubricate the oral cavity and initiate the digestion of carbohydrates and lipids, and protective functionsSalivaSource: parotid, submandibular, sublingual salivary glandsComposition: mucin, salivary amylase, bicarbonate, lysozyme
23 myoepithelial cellsthey are contractile epithelial cells, they are located between the secretory cells and the basement membrane. Each myoepithelial cell has long cytoplasmic processes which wrap around a secretory unit. Hence, contraction of the myoepithelial processes can squeeze secretory product from the secretory unit into its duct.
33 Duct system Intercalated ducts Striated ducts Excretory ducts lined by a low cuboidal epithelium, many contain myoepithelial cells.Striated ductslined by columnar cells. They have prominent basal surface invaginations associated with many mitochondria.Excretory ductsLined simple cuboidal, Are the larger ducts that empty into the oral cavity.
44 1. Surface mucous cellsa. They form a simple columnar epithelium that covers the gastric mucosa.b. They secrete a continuous mucous layer that prevents the proteinase solutions in the stomach.
45 2.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.
46 3. 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
47 4. Parietal cellsa. Rounded or pyramidal cells, intensely eosinophilic cytoplasm.Resting---tubulovesicular---few microvilliActivity---canaliculus---more microvillib. Parietal cells secrete HCl and Intrinsic factorDiagram of a parietal cell
48 5.Stem cells Found in the isthmus and neck regions. 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.
49 6. Endocrine cellsa. In the neck and base of gastric glands
51 pernicious anaemia.Vitamin B12's primary functions are in the formation of RBC and the maintenence of a nervous system.Absorption of B12 requires the secretion of intrinsic factor.Certain people are unable to produce intrinsic factor.
52 What prevents the proteolytic enzymes and low pH from damaging the stomach?A thick coat of bicarbonate containing mucus coats the stomach wall.Mucosal epithelial cells are joined by tight junctionsDamaged epithelial cells are shed & quickly replaced.
57 B. Mucosa1. The epithelium of intestine villi2. Intestinal glands (intestinal crypts)3. Five types of cells in intestinal mucosal epitheliumAbsorptive cellsGoblet cellsPaneth’s cellsEndocrine cellsMicrofold cells
65 b. Goblet cellsInterspersed between the absorptive cellsduodenumjejunumincreasingileumGoblet cell secretion of mucin .The mucous lubricates and forms a barrier which protects the mucosal epithelium from potentially noxious intraluminal substances.
66 The Paneth cellsoccur in small groups at the base of the intestinal crypt.These have both phagocytic and secretory propertiesThey secrete lysozyme (which dissolves the cell wall of bacteria) and secretory IgA.
68 Peyer‘s patches Peyer‘s patch Appears as a dome shape area lack of villi.the covering epithelium consist of M cells.villiPeyer‘s patch
69 M cells (microfold cells) are specialized epithelial cells overlying the lymphoid follicles of Peyer‘s patches.M cells can endocytose antigens and transport them to the underlying macrophages and lymphoid cells. Which then migrate to other compartments of lymphoid system (nodes).
72 Small Intestine Functions: Digestion: neutralize acid from stomach, add digestive enzymes and bile, break proteins, carbohydrates and lipids to absorbable materialsAbsorption: 95% of food absorbed hereSlide 14.10B
73 Location: in submucosa of duodenum. BRUNNER GLANDSLocation: in submucosa of duodenum.Function: protection the proximal small intestine by neutralizing the acid-containing chyme.
74 Ⅲ. Large intestineThe mucous membrane does differ from that of the small intestine in several aspects: 1. There are no villi. 2. The intestinal crypts are larger, more numerous and more densely packed. 3. One-fourth of the epithelial cells are goblet cells. Thus the large intestine is well lubricated 4. There are no Paneth cells.
77 AppendicitisIt is thought that the opening from the appendix into the cecum becomes blocked.The lymphatic tissue in the Appendix may swell and block the Appendix.Bacteria which normally are found within the appendix then begin to invade the wall of the Appendix.
78 Homework Describe the structure of the stomach fundus gland. Describe the cell type of the small intestine.