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. d. stem cell: undifferentiated cell e. endocrine cell , i.e
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-HCO3 barrier:
mm thick mucous
HCl PH:
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,
-enlarge the surface area to 30 times
cell coat: um
-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. CT (LC, macrophage, plasma cell and eosinophil and mast cell)
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）