Digestive system III Histology

Category: Education

Presentation Description

No description available.


Presentation Transcript

Digestive system III : 

Digestive system III Dr Pankaj Maheria

Small intestine : 

Small intestine

General features : 

General features About 6 meters long Division Duodenum Jejunum Ileum Function : Principal site of absorption of products of digestion. Secret the some hormones

General features : 

General features Digestion complete in small intestine. To facilitate absorption , the luminal surface area is increased 400 – 600 fold by presence of following structure Plica circularis Intestinal villi Microvilli

Plicae circularis : 

Plicae circularis Permanent circular mucosal and submucosal fold Increased surface area 2 to 3 times.

Intestinal villi : 

Intestinal villi Minute finger like projection of mucosa Contain Central core of lamina propria Single lacteal Capillary loop Smooth muscle derived from musculari mucosa

Intestinal villi : cell : 

Intestinal villi : cell Enterocytes Goblet cells Paneth cells Neuroendocrine cell Stem cells Intraepithelial lymphocytes

Microvilli : 

Microvilli Very minute finger like projection of plasma membrane of absorptive columnar epithelium. Striated border Increase surface area : 20 Basic component Protein Carbohydrates Lipids -

Mucosa : 

Mucosa Epithelium: Simple columnar absorptive with goblet cells Intestinal villi Thick glycocalyx Crypts of Lieberkuhn Columnar cell Goblet cells Paneth cells

Slide 11: 

Lamina propria Cells Fibroblast, Mast cells, Plasma cells, Lymphocytes Crypts of Lieberkuhn Lacteals Capillary loops Muscularis mucosa Two layers of smooth muscle Inner circular Outer longitudinal

Serosa : 

Serosa Adventitia: loose connective tissue without peritoneum Serosa : peritoneum over a layer of connective tissue.

Submucosa : 

Submucosa Region variation Brunner’s glands in Duodenum Peyer’s patch None of above in jejunum

Muscularis externa : 

Muscularis externa Same as general plan

Slide 16: 

Salient microscopic features of each region of small intestine

Duodenum : 

Duodenum Villi are leaf like Muscularis mucosa disturbed Brunner’s gland Enteroendocrince cells

Brunner’s gland : 

Brunner’s gland Mucous gland Submucosa Branched coiled tubular Open in bottom of crypt Secretion : Thin alkaline secretion

Enteroendocrine cells : 

Enteroendocrine cells In mucosa Secretion: Urogastrone Secretin Cholecystokinin

Jejunum : 

Jejunum Villi are finger like Submucosa Lack of glands and Peyer’s patches

Ileum : 

Ileum Villi are thin and slender Submucosa Peyer’s patch M cells

Slide 23: 

The GI tract absorbs everything!!! [except cellulose]

Large intestine : 

Large intestine

General features : 

General features Consist of Caecum, Appendix, Colon , Rectum and anal canal Harbours some nonpathological bacteria that produce vitamin B12 and vitamin K. Absorption of water and electrolytes Produces lots of mucus that lubricate and facilitates easy passage of faeces. Lacks of intestinal villi

Slide 27: 

Salient microscopic features of each region of large intestine

Vermiform appendix : 

Vermiform appendix Small angular lumen compared to thick wall No villi Few short crypts Ring of lymphoid follicles with germinal centers in lamina propria Disrupted muscularis mucosa

Caecum and colon : 

Caecum and colon No villi Crypts are well developed and lined by plenty of goblet cells. Paneth cells are absent in crypts Muscularis externa Taenia coli Serosa Appendices epiploicae

Rectum : 

Rectum Long crypts of Lieberkuhn Lymphoid tissue is less abundant in lamina propria Lacks of taenia coli Serosa replace by adventitia in lower part

Anal canal : 

Anal canal Epithelium Above anal valves: stratified cuboidal At anal valves: stratified squmous At the anal orifice: epidermis of skin No crypts No musculari mucosa

Anal canal : 

Anal canal Submucosa : rich vascular plexus Inner circular layers of smooth muscle: internal anal spincter Externally at orifice : skeletal muscle , external anal spincters.

Slide 33: 

Coeliac disease Ulcerative Colitis Familial adenomatous polposis Gardner syndrome Adenocarcinoma

Slide 34: 

Thank you…..

authorStream Live Help