Chapter 13 Digestive tract

1. Chapter 13 Digestive tract

2. ---Digestive system: • Digestive tract • Digestive gland

3. 1. Components of digestive tract ---oral cavity ---pharynx ---esophagus ---stomach ---small intestine ---large intestine

4. 2. General plan of digestive tract ---Except for oral cavity and pharynx, all other organs share a similar histological plan

5. 1) mucosa ---epithelium: • stratified squamous epi.: protecting • simple columnar epi,: digestion and absorption ---lamina propria: LCT-compact CT: contain more cells and fiber • BV, LV-capillaries • Lymphoid T • glands: structures formed by invagination of epi. into lamina propria ---muscularis mucosa: a thin layer of SM

6. 2) submucosa: more dense CT • small artery and vein, LV • glands (esophagus and duodenum) • submucosa N plexus: -multipolar N -unmyelinated NF -function: regulate the contract of SM and secreting of gland *Plica: projection of mucosa and submucosa

7. 3) tunica muscularis • smooth muscle • skeletal muscle • inner circular and outer longitudinal *Nerve plexus: regulate the movement of M

8. 4) tunica adventitia: CT serosa: CT + mesothelium fibrosa: LCT

9. 3. Esophagus 1)mucosa: • epithelium: stratified squamous epi. • lamina propria: CT • muscularis mucosa: longitudinal arranged SM 2)submucosa: • LCT • esophageal gland: mucous gland

10. 3)muscularis: • inner circular and outer longitudinal • upper 1/3: skeletal muscle • middle 1/3: mixed of skeletal M and smooth muscle • lower 1/3: smooth muscle 4)adventitia: fibrosa

11. 4. Stomach ---dilated part ---store food temporarily ---digest protein primarily ---absorb part of water and Ions

12. 1)Mucosa: ---plica-longitudinal ---shallow ditch- gastric area (2-6mm) ---gastric pit- small depressions

13. ①epithelium: simple columnar epi • surface mucous cell: -tall columnar -N ovoid, basally-located -mucinogen granule -tight junction -high HCO3- undissolved mucus • less endocrine cell

15. ②lamina propria: CT contains fibroblast, LC, plasma cell, mast cell and eosinophil, SM • gastric gland -fundic gland • cardiac gland: mucous gland • pyloric gland: mucous gland

17. * Fundic gland -long, branch tube liked gland: /neck, body and basa -five types of cells can be seen

19. a. chief cell or zymogenic cell ---structure: LM: • columnar • Round, basally-located Nucleus • cytoplasm: /basal-basophilic /apical-zymogen granules EM: RER, Golgi apparatus ---function: secret pepsinogen

21. b. parietal cell or oxyntic cell ---structure: LM: • large, pyramidal or spherical • round centrally-located nucleus • eosinophilic cytoplasm EM: • intracellular secretory canaliculus-invaginations • tubulovesicular system • mitochondria

22. ---function: i.secret hydrochloric acid (HCl) -synthesis processes of HCl: in intracellular secretory canaliculus • H+ K+ -ATP pump: get H+ from cell • Cl- channel: get Cl- from blood • H+ +Cl-→HCl(intracellular secretort canaliculi) -function of HCl: • HCl ↓ pepsinogen→pepsin • kill the bacterium

23. ii.secret intrinsic factor- glycoprotein + VB12→absorption of VB12

24. c. mucous neck cell • less, neck part • columnar • flattened, basally-located N • pale stain in HE stain d. stem cell: undifferentiated cell e. endocrine cell , i.e • G cell: secreting gastrin(胃泌素), promote secretion of parietal cell • D cell: secreting somatostatin（生长抑素）, inhibit the secretion of parietal cell

25. * cardiac gland and pyloric gland: mucous gland, contain G cell, which secretes gastrin, to promote the secreting of parietal cell * Mucous-HCO3barrier: • 0.25-0.5mm thick mucous • HCl PH: 0.9-1.5 • H+ + HCO3- → H2CO3 →H2O + CO2 ↑ bicarbonatase

26. ③ Muscularis mucosa: inner circular and outer longitudinal arranged SM 2)submucosa: CT with BV, LV, N and fat cell 3)muscularis : thicker • inner oblique • middle circular • outer longitudinal 4) advantitia: serosa

27. 5. Small intestine ---duodenum ---jejunum ---ileum

28. 1)Mucosa ---circular plica ---intestinal villus ---small intestinal gland

29. ①epithelium: ---absorptive cell: • microvilli: striated-border -1-1.4um long, 80nm in D, 2000-3000 -enlarge the surface area to 30 times • cell coat: -0.1-0.5um -enzymes: trypsinogen（胰蛋白酶原）, amylase（淀粉酶） - glucose and protein • enzymes-adipose • SER

30. ---goblet cell ---endocrine cell: • I cell: secreting cholecystokinin（胆囊收缩素） • S cell: secreting secretin（促胰液素）

31. ②lamina propria: CT (LC, macrophage, plasma cell and eosinophil and mast cell)

32. a. villus: is the projection of epithelium and lamina propria epithelium: absorptive cell, goblet cell and endocrine cell lamina propria: CT with central lacteal, fenestrated cap. and SM

34. b. small intestinal gland: is the invagination of epi.into propria • absorptive cell • goblet cell • endocrine cell • stem cell • Peneth cell

35. Peneth cell: LM: -pyramidal, basally- located, in groups -apical: acidophilic G- Lysozyme（溶菌酶） EM: -protein-secreting cell feature Function: related to immune function

36. goblet cell

37. absorptive cell

38. ③muscularis mucosa: SM inner circular and outer longitudinal

39. 2)submucosa: CT Large BV and LV duodenal gland: mucous gland-secreting epidermal growth factor（表皮生长因子）, promote the epithelial cell proliferation of small intestine

40. 3)muscularis: SM, inner circular and outer longitudinal 4)adventitia: serosa and less fibrosa

41. 6. Large intestine ---absorb water and ions ---structure feature: a.no villus and no circular plica b.well-developed large intestinal gland c.contain more goblet cells d.taeniae coli（结肠带）: longitudinal bunds bag coli（结肠袋）