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: a. serous acinus: structure: pyramidal or cuboidal round basally-located N apical: zymogen granule-acidophilic basal: basophilic-RER, ribosome function: secret salivary amylase （淀粉酶）

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

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

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.

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

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

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

胰腺 - 图 2. Pancreas

---capsule: CT, septa ---parenchyma: /exocrine pancreas /endocrine pancreas

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 Digestive enzymes: trypsinogen （胰蛋白 酶原）, amylase （淀粉酶）,lipase （脂酶） and chymotrypsinogen （糜蛋白酶原）,

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

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

A cell

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

B cell

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

d. PP cell: EM: secrete granule: small, nm function: secrete pancreatic polypeptide （胰多肽） to inhibit the secreting of pancreatic liquid, movement of viscera and contraction of gall bladder

e. D 1 cell: 2-5%, peripheral, irregular EM: small, nm, function: secrete VIP (vasoactive intestinal peptide ，血管活性肠肽 ) f. C cell: undifferentiated cell

肝-图肝-图肝-图肝-图 3. Liver

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

1) hepatic lobule: basic structural unit ， ， 000 ， mm long, 1 mm in across D ---polygonal (irregular) ---structure: central vein hepatic plate: radiating arranged hepatic sinusoid

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

② Hepatic plates ---formed by single layer of hepatocytes

a. hepatocyte: LM: polygonal, um eosinophilic N: -large, pale, round, centrally- located -1/4 binucleate

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

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 （胆红素） microbody: -round, um -contain catalase （过氧化氢酶） and peroxidase （过氧化物酶） inclusions: glycogen, lipid droplet, pigment

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

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

③ Hepatic sinusoid ---space between hepatic plates ---structure:

9-12 um endothelial cell: fenestrated, gap, plasmalemmal vesicles -liver macrophage (Kupffer cell) -large granular lymphocyte: NK cell

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

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

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

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

a. interlobular arteries: branches of hepatic A small A: endothelium 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.

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 ｛

Blood circulation of liver 中央 V 小叶下 V 肝V肝V 血窦 终末门微 V 小叶间 V 门V门V 终末肝微 A 肝A肝A 小叶间 A

4) Passage of bile 肝细胞 胆小管 闰管 小叶间胆管 左右肝管 肝总管 胆囊管 胆囊 或 经胆总管到十二指肠

谢谢！