Lectures: Po/Monday 9:00 – 10:40 A11 Room 234 Practicals: Út/Tuesday 10:30 – 13:00 Microscopic hall of the Dept. 30 31 32 33 Recommended web-address: http://www.med.muni.cz/histol/vyukac.htm Literature for study: Junqueira Moore_Persaud Basic Histology The Developing Human http://covers.elsevier.com/165/9781416037057.jpg ISBN: 978-1-4160-3705-7 Before We Are Born, 7th Edition - Essentials of Embryology and Birth Defects With STUDENT CONSULT Online Access By Keith L. Moore, BA, MSc, PhD, FIAC, FRSM and T. V. N. Persaud, MD, PhD, DSc, FRC Path(Lond) 368 pages 1308 ills ($54.95, Softcover) Moore_Persaud_ 2008 Outline of development of the digestive system – a revision GENERAL STRUCTURE OF THE ALIMENTARY CANAL (MICROSCOPIC STRUCTURE OF THE ORAL MUCOSA) MICROSCOPIC STRUCTURE OF THE ESOPHAGUS, STOMACH, AND SMALL AND LARGE INTESTINE HISTOPHYSIOLOGY OF THE INTESTINE AND BLOOD CIRCULATION Lecture 1 ESS_3rd semester Digestive system consists of * the alimentary canal - oral cavity, oropharynx, esophagus, stomach, small and large intestines, rectum and anus * * associated glands - salivary glands, liver and pancreas function is to obtain from ingested food the metabolites necessary for the growth and energy needs of the body food is digested and transformed into small molecules that can be easily absorbed through the lining of alimentary canal 001 Outline of development of the digestive system Development of the alimentary canal: it constitutes during the 4th week from 3 separate embryonic anlages (organs): the stomodeum (primitive mouth) – develops on the cephalic end of the embryo, is limited by 5 frominences (frontonasal, 2 maxillary, 2 mandibular) - ectoderm oropharyngeal membrane the primitive gut – arises by incorporation of the dorsal part of the yolk sac into embryo during cephalocaudal and lateral folding of the embryo gut is connected to the yolk sac by means of the vitelline (omphalomesenteric) duct - endoderm cloacal membrane the proctodeum (anal pit) - develops on the caudal end of the embryo between future bases of lower limbs - ectoderm • • stomodeum • oropharyngeal membrane • • primitive gut • foregut • • midgut • • hindgut • • cloacal membrane • proctodeum • •ventral mesenterium •dorsal mesenterium embryo_sagittal membranes are temporary structures and soon are ruptured – all three segments become continuos Trávící systém II - 33 Trávící systém II - 33 Segments of the primitive gut: - foregut - midgut - hindgut gut is suspended from the ventral and dorsal body wall by mesenteries the dorsal mesentery – caudal end foregut – hindgut the ventral mesentery – shorter during further development midgut rapidly grows in length to form 2 loops (duodenal and umbilical), rotates and leaves even the abdominal cavity (physiological herniation) Trávící systém III - 22 Trávící systém II - 34 Trávící systém II - 39 after reposition of the herniation midgut occupies its defenitive position while the ectoderm of the stomodeum and proctodeum as well as the endoderm of the gut differentiate into the epithelium of the alimentary canal, the muscular and fibrous elements + visceral peritoneum derive from the splanchnic mesenchyma that surrounds the lining of the primitive gut Development of associated glands: (salivary glands, liver and pancreas) develop from the endoderm (ectoderm) that gives rise to specific cells (hepatocytes, exo- and endocrine cells of the pancreas (the parenchyma) DERIVATIVES OF THE PRIMITIVE GUT The hindgut: • the descending colon • the sigmoid colon • the rectum • the superior portion of the anal canal • the epithelium of the urinary bladder and most of the urethra The foregut: • the pharynx and branchiogenic organs • the lower respiratory tract • the esophagus • the stomach • the duodenum proximal to the opening of the bile duct • the liver and pancreas + the biliary apparatus • The midgut: • the small intestines, including the part of the duodenum distal to the opening of the bile duct • the caecum and appendix • the ascending colon • the transverse colon General structure of the definitive alimentary canal 001 Layers of the wall of the alimentary canal: Ømucous coat - tunica mucosa Ø Øsubmucous coat - tela submucosa Ø Ømuscular coat - tunica muscularis Ø Øserous coat (tunica serosa) or adventitia (tunica adventitia) 4layers_ Sublayers : F15_01 oralcavity MICROSCOPIC STRUCTURE OF THE ORAL MUCOSA Figure_12-05 006 Bez názvu 1 kopie Trávící systém I - 5 Apex linguae - spodina tongue Trávící systém I - 10 Chuťové pohárky 008 MICROSCOPIC STRUCTURE OF THE ESOPHAGUS, STOMACH, AND SMALL AND LARGE INTESTINE HISTOPHYSIOLOGY OF THE INTESTINE AND BLOOD CIRCULATION travtrubice external appearance of the mucosa shows close relation to function of the respective segment folds (transient or permanent) pits – tubular invagination of the epithelium villi – mucosal processes (epithelium and lamina propria) Trávící systém II - 1 Jícen - schéma Esophagus -20- 25 cm long muscular tube wall consists of 4 layers Stomach (lat. ventriculus, gr. gaster, stomachus) segment of alimentary canal that digests food and secretes hormones food mixed with gastric juice = chyme volume cca 2 l cardia, fundus+body, pylorus wall shows 4 layered organization: 1. mucous coat (pale, grayish pink) gastric areas (2-6 mm in d.) gastric pits (foveolae gastricae) - are tiny grooves 2. submucous coat - loose areolar tissue 3. muscular coat - inner oblique - middle circular - outer longitudunal 4. serous coat - peritoneal covering stomach 004 F15_10 003 Cardia ventriculi: a narrow circular band (1,5 -3,0 cm in with) at the transition between esophagus and stomach site of change of the epithelium mucous cardiac glands in the lamina propria (mucus + lysozyme) cardia ¬ cardia.jpg ¬ cardia_ cardia ¬ ¬ Fundus et corpus ventriculi: 005 002 Fundus et corpus ventricul – gastric areas: Mucosa of the fundus and body: - simple columnar epithelium - lamina propria mucoae - loose areolar conn. tissue - lamina muscularis mucoae F15_10 žaludek lamina propria is penetrated with branched tubular glands- gastric (fundic) glands 3 parts: base, body and neck 4 cell types: - chief (pepsinogenic) - parietal (oxyntic, HCl) - mucous neck - enteroendocrine gastric juice krycíbb hlavníbb F15_15 an enzyme typical of oxyntic cells is carbonic anhydrase Trávící systém II - 12 Pylorus Pylorus ventriculi: deeper gastric pits, reticular conn. tissue, pyloric glands F15_10 Trávící systém II - 13 Pylorus pylorus pylorus-zl Pylorus ventriculi: deeper gastric pits, reticular conn. tissue, pyloric glands •Small intestine (intestinum tenue) •5–7 m in length •digestion, absorption •3 segments: duodenum, jejunum and ileum •wall consists of 4 layers: mucous, submucous, muscular a serous coat • •Surface specialization of the mucosa: •1. plicae circulares (valves of Kerckring) - transverse and permanents folds • with submucous core •2. intestinal villi and crypts - villi - finger-like or leaf-like projections 0.5 -1.5 mm in length • - crypts (of Lieberkühn) - tubular invaginations • (0.5 mm in depth) between bases of villi •3. microvilli - folds of the apical plasma membranes of enterocytes • „brush border“ in the LM • circular plicae (valves of Kerckring, plicae circulares) Intestinal villi (villi intestinales) Microvilli smalintest1 006 Small intestine - surface circular plicae (plicae of Kerckring, plicae circulares) •Intestinal villi (villi intestinales) • Microvilli int_tenue F15_27 smalintest4 Trávící systém II - 21 Jejunum Trávící systém II - 23 Jejunum Intestinal villi (villi intestinales) and crypts of Lieberkühn •tunica mucosa • Epithelium - simple columnar • Lamina propria mucosae • Lamina muscularis mucoase • •the epithelium: • absorptive cells: enterocytes • secretory cells: goblet cells, Paneth´s cells, enteroendocrine cells • Trávící systém II - 25 Jejunum - resorpční epitel smalintest4 F15_27 F15_21 Trávící systém II - 19 Duodenum - krypty Paneth´s cells smalintest4 Intestinal villus (-i)- structure 007 F15_27 intestinal villus Trávící systém II - 16 Duodenum - schéma •Duodenum Bez názvu2 kopie Duodenum Bez názvu 1 kopie Jejunum F15_34 BLOOD AND LYMPH CIRCULATION smalintest2 F15_25 absorption F15_41 •Large intestine (intestinum crassum) • •1,5 m in length • •intestinum caecum with vermiform appendix (appendix vermiformis), colon (colon ascendens, transversum, descendens, sigmoideum) and rectum (intestinum rectum) •faeces • •4 layers: mucous, submucous, muscular a serous coats • •1. the mucous tunic • is smooth without intestinal villi, but crypts of Lieberkühn are retained, absence of Paneth cells • - simple columnar epithelium (enterocytes, goblet cells, endocrine cells) • - lamina propria - reticular tissue (lymph nodules) • - muscularis mucosae • •2. the submucous coat - wide, made up of areolar connective tissue • •3. the muscular coat - inner circular and outer longitudina (3 taeniae coli) • •4. the serous coat or adventitia (deposits of adipose tissue in the serosa - • appendices epiploicae) • •plicae semilunares : permanent plicae made up of t. mucosa, submucous coat and •t. muscularis • largeintest largeintest1 the large intestine mucosa: Bez názvu5 kopie Bez názvu4 kopie the mucous tunic appendic Trávící systém II - 31 Appendix - schéma Vermiform appendix Bez názvu6 kopie rectum rectum The rectum