Chapter 13 Digestive tract

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Chapter 13 Digestive tract
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• ---Digestive system
• Digestive tract
• Digestive gland

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

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

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• 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

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• 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

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

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• 4) tunica adventitia CT
• serosa CT mesothelium
• fibrosa LCT

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3. Esophagus

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

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• 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

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4. Stomach

• ---dilated part
• ---store food temporarily
• ---digest protein primarily
• ---absorb part of water and Ions

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

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

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

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

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• 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

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

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• ---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

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• ii.  secret intrinsic factor- glycoprotein
  VB12?absorption of VB12

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• 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(???), promote
  secretion of parietal cell
• D cell secreting somatostatin(????), inhibit
  the secretion of parietal cell

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• cardiac gland and pyloric gland mucous gland,
  contain G cell, which secretes gastrin, to
  promote the secreting of parietal cell
• Mucous-HCO3 barrier
• 0.25-0.5mm thick mucous
• HCl PH 0.9-1.5
• H HCO3- ? H2CO3 ?H2O CO2
• ?
• bicarbonatase

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• ? 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

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5. Small intestine

• ---duodenum
• ---jejunum
• ---ileum

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• 1)      Mucosa
• ---circular plica
• ---intestinal villus
• ---small intestinal gland

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• ?epithelium
• ---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(?????), amylase(???) -
  glucose and protein
• enzymes-adipose
• SER

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• ---goblet cell
• ---endocrine cell
• I cell secreting cholecystokinin(?????)
• S cell secreting secretin(????)

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• ?lamina propria
• CT (LC, macrophage, plasma cell and eosinophil
  and mast cell)

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• 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

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

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• Peneth cell
• LM
• -pyramidal, basally- located, in groups
• -apical acidophilic G- Lysozyme(???)
• EM
• -protein-secreting cell feature
• Function related to immune function

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goblet cell
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absorptive cell
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• ?muscularis mucosa SM inner circular and outer
  longitudinal

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• 2)      submucosa CT
• Large BV and LV
• duodenal gland mucous gland-secreting epidermal
  growth factor(??????), promote the epithelial
  cell proliferation of small intestine

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• 3)  muscularis SM, inner circular and outer
  longitudinal
• 4)   adventitia serosa and less fibrosa

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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(???) longitudinal bunds
• bag coli(???)