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Chapter 14 Digestive gland

Chapter 14 Digestive gland. ---small gland: fundis gland, small intestinal gland ---large gland: salivary gland, pancreas, liver. 1. Salivary gland. 1) General structure of exocrine gland ---Capsule: CT, which separate the parenchyma into lobules ---lobule:. ① acinus:

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Chapter 14 Digestive gland

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  1. Chapter 14 Digestive gland

  2. ---small gland: fundis gland, small intestinal gland ---large gland: salivary gland, pancreas, liver

  3. 1. Salivary gland 1) General structure of exocrine gland ---Capsule: CT, which separate the parenchyma into lobules ---lobule:

  4. ① acinus: a. serous acinus: structure: • pyramidal or cuboidal • round basally-located N • apical: zymogen granule-acidophilic • basal: basophilic-RER, ribosome function: secret salivary amylase

  5. b. mucous acinus: structure: • pale-stained, slight-blue, flattened N against the basal membrane • mucinogen granule • Golgi, RER, mitochondria c. mixed acinus: several serous cell attached to mucous acinus – serous demilune

  6. ②duct: • intercalated duct: • simple squamous epi. • simple cuboidal epi. • connect with acinus

  7. b. striated duct (secretory duct): intralobule • simple columnar epi. : • tall cell, acidophilic • round N, located at apical part • longitudinal striation: plasma membrane infolding c. interlobular duct and major duct : simple columnar epi. or pseudostratified ciliated columnar epi.

  8. 2) structural feature of each salivary gland a.parotid gland: -serous -long intercalated duct, short striated duct

  9. b.submandibular gland: -mixed( mainly serous, less mucous and mixed) -short intercalated duct, long striated duct

  10. c.sublingual gland: -mixed(mainly mucous, more serous and mixed) -more demilunes, no intercalated duct, under-developed striated duct

  11. * granular convoluted tubule, GCT: ---a segment convoluted duct between intercalated duct and striated duct in submandibular gland ---epithelial cell: • pyramidal in shaped, with large N • apical cytoplasma: eosinophilic granules • granules contain: i.growth factors-NGF, EGF,MGF, EGSF, EGF ii.homeostasis factors: renin, Kallikrein, CSF, ACF iii. digestive enzymes: amylase, ribonuclease, acid phosphatase iv.intracellular regulating factor

  12. 2. Pancreas ---capsule: CT, septa ---parenchyma: /exocrine pancreas /endocrine pancreas

  13. 1) exocrine pancreas ---acinus: serous *centroacinar cell: small, pale cell with round or ovoid N, derived from epithelial cell of intercalated duct ---duct: long intercalated duct ---function: secret pancreatic liquid • 1-2L/D, PH 7.8-8.4 • Digestive enzymes: trypsinogen, chymotrypsinogen, amylase and lipase

  14. 2) endocrine pancreas( pancreas islet) ---170.000-200.000, constitute about 1% of total pancreas volume ---75-500 um ---HE: cells arranged into cord with CT rich in fenestrated cap.

  15. ---EM: a.A cell: • 20%. Large polygonal in shaped, peripheral-distributed • EM: secretory G: large, 190-310 nm, round with dense core • function: secret glucogon - 29 amino acid residues protein ↓ glycogen→ glucose

  16. b.B cell: • 75%, small, centrally-distributed • EM: secretory G: different diameter, 225-375 nm with one or several dense core • function: secret insulin - 51 amino-acid residues

  17. c. D cell: • 5%, ovoid, fusiform, peripheral-distributed, between A, B cells • EM: -gap junction with A,B cell -secretory G: large, 190-370nm, low-density core • function: secrete somatostatin to inhibit the secreting of A, B, PP cell

  18. d. PP cell: • EM: secrete granule: small, 110-170 nm • function: secrete pancreatic polypeptide to inhibit the secreting of pancreatic liquid, movement of viscera and contraction of gall bladder e. D1 cell: • 2-5%, peripheral, irregular • EM: small, 140-190 nm, • function: secrete VIP(vasoactive intestinal peptide) f. C cell: undifferentiated cell

  19. 3. Liver ---largest, 2% of body weight ---capsule: DCT, insert into parenchyma to separate the parenchyma into hepatic lobule ---hepatic lobule ---portal area

  20. 1) hepatic lobule: basic structural unit ---500.000-1.000.000 ---2 mm long, 1 mm in across D ---polygonal prism( irregular) ---structure: • central vein • hepatic plate: radiating arranged • hepatic sinusoid

  21. ①Central vein: • small vein: endothelium + CT • 45 um • receive the blood from sinusoids

  22. ②Hepatic plates ---formed by single layer of hepatocytes a. hepatocyte: LM: • polygonal, 20-30 um • eosinophilic • N: -large, pale, round, centrally- located -1/4 binucleate

  23. EM: • mitochondria: 1000-2000, 20% total volume • RER: involve in the synthesis of albumin, fibrinogen, clotting factor, lipoprotein and complement protein • SER: contain enzymes- oxidoreductase (oxidase, reductase), hydrolase, transterase, synthetase, involve in the formation of bile and the metabolism of adipose, glucose and hormones

  24. Golgi apparatus: involve in -formation of bile -process, condense and storage of proteins -formation of lysosome • Lysosome: involve in phagocytosis activity and metabolism of bilirubin • microbody: -round, 0.2-1.0 um -contain catalase and peroxidase • inclusions: glycogen, lipid droplet, pigment

  25. b. bile canaliculus: ---cell membrane of adjacent hepatocytes depress to form a tubular system between hepatocytes

  26. ---structure: • silver preparation: dark-brown colored network • 0.5-1um • Microvilli • tight junction, desmosome

  27. ③ Hepatic sinusoid ---space between hepatic plates ---structure: LM: • 9-12 um • endothelial cell: fenestrated, gap, plasmalemmal vesicles • RF • cavity: -liver macrophage(Kupffer cell) -large granular lymphocyte: NK cell

  28. EM: • Perisinusoidal space: Disse space - narrow space between endothelial cell and hepatocytes • 0.4 um width • blood plasma • microvilli • RF • fat-storing cell:

  29. *fat-storing cell: -irregular, with processes -EM: large lipid droplets, RER, mito, Golgi -function: storage of vitamin A(E,K), synthesis of collagen

  30. * The three kinds of different surfaces of hepatocytes ---face adjacent cell each other: 55% ---face the sinusoids: 35% ---form bile canaliculus: 10%

  31. 2) portal area ---areas(triangle-shaped or irregular-shaped) where adjacent hepatic lobules meet ---contains CT and several ducts

  32. a. interlobular arteries: • branches of hepatic A • small A: endothelium + 3-4 layers of SM b.interlobular vein: • branches of portal vein • small vein: endothelium + less CT and single SM c.interlobular bile duct: • simple cuboidal or low columnar epi.

  33. 3) Blood circulation of liver hepatic A →interlobular A →terminal hepatic arteriole portal V→interlobular V→terminal portal venule → hepatic sinusoid →central vein→sublobular V →hepatic V→inferior vena cava 4) Passage of bile ｛

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