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Bloc E - GI & Metabolism > Feb19 M1-Histo Liver and Pancreas > Flashcards

Feb19 M1-Histo Liver and Pancreas Flashcards

1
Q

how liver separated in lobules

A

CT penetrates and splits it

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2
Q

liver fcts

A
  • endocrine (albumin, transferrin, etc,)
  • exocrine (bile, etc.)
  • conjugation and elimination
  • conversion (T4 to T3)
  • hemopoiesis (fetal)
  • storage (glycogen, lipids)
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3
Q

liver lobule where bile going

A

in the triad (on outside of lobule), bile going in opposite direction. duct called cholangiole and then bile duct

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4
Q

lobule histology

A
  • cords of hepatocytes. small canaliculi between adjacent hepatocytes lead to cholangiole
  • portal venule and hepatic arteriole lead to capillaries (sinusoids) in the lobule that will join
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5
Q

bile duct cells characteristics (in portal space of the lobule)

A

cuboidal cells. prominent lumen

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6
Q

charact of sinusoids in lobules

A
  • covered by layer of endothelial cells

- some macrophages there: Kuppfer cells (endocytose RBC,s form particles, etc.)

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7
Q

name of space between hepatocytes and the endothelial cells of the sinusoids

A

space of Disse

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8
Q

where bile canaliculi are and why don’t reach space of Disse

A
  • between hepatocytes and between hepatocytes plates.

- tight junctions and desmosomes between hepatocytes so can’T go to space of Disse.

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9
Q

hepatocytes EM charact

A
  • MICROVILLI
  • peroxisomes (membrane with crystals inside)
  • endocytosis with lysosomes, golgi, RER, SER
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10
Q

characteristics of sinusoids (why called like that)

A

don’t rest on BM. rest on reticular fibers

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11
Q

4 components of endocytic system of the liver

A
  1. endocytic vesicle
  2. endosome
  3. maturating lysosome
  4. lysosome
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12
Q

how endocytosis works in the liver

A

receptor mediated (liver has receptors for almost all hormones in the body to remove them from circulation)

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13
Q

where enzymes (or hormones) digested after endocytosis and what happens to the receptor

A
  • in maturating lysosome

- R sent back to surface (recycled)

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14
Q

important receptors on the liver

A

R for LDL, HDL, chylomicrons (produced by enterocytes)

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15
Q

what happens when hepatocyte internalizes a chylomicron

A
  • lipids stored in SER

- R sent back to surface to internalize more chylomicrons

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16
Q

organelles of secretory system of hepatocytes

A

RER: synthesis of proteins like apoB
SER: TGs (and also phospholipids, cholesterol, long chain FAs) sent to golgi apparatus.
bile synthesis and conjugation + bilirubin conjugation
Golgi: apoB conjugated to lipids forming a lipoprotein called VLDL + packs TGs in vesicles
exocytic vesicles

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17
Q

VLDL goes where and what does it contain

A

goes in sinusoid, contains cholesterol

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18
Q

what happens to VLDL in the blood

A
  • lipoprotein lipase on caps converts it to IDL

- hepatic lipase converts IDL into LDL

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19
Q

what happens to LDL in the blood

A
  • some goes to peripheral tissues (LDL contains cholesterol), they need cholesterol for growth, is an important part of plasma membranes
  • rest of LDL goes to liver (LDL-R)
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20
Q

charact of LDL-R on hepatocytes

A
  • almost everyone has mutations, some are more severe
  • inefficient LDL-R = cholesterol stays in circulation for longer time. oxidized. macrophages eat it, goes in intima, atherosclerosis, endothelium disruption, clot formation
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21
Q

peroxisome function in hepatocytes

A
  • H2O2 made into H2O and O2
  • beta-oxidation of long chain FAs
  • catabolism of ETOH
  • cholesterol synthesis
  • purines break down (AMP, GMP)
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22
Q

SER functions

A
  • send lipids to Golgi
  • bile acids synthesis: 1. bile cholesterol + taurine = taurocholic acid
    2. bile cholesterol + glycine = glycocholic acid
  • bilirubin conjugation into glucuronic acid
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23
Q

where SER sends its contents (ultimately)

A
  • lipids to Golgi

- bile salts and conjugated bilirubin to cholangioles (bile canaliculus)

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24
Q

why viral hepatitis causes jaundice

A

disrupts tight junctions. bilirubin (direct) goes from bile canaliculi to sinusoids

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25
Q

big and small dots seen on liver EM

A

big dots = fat

small dots = glycogen (stored)

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26
Q

venous drainage of the liver

A

sinusoids go to central vein to sublobular vein to hepatic vein to IVC

27
Q

bile system drainage of liver

A

bile canaliculus (between hepatocyte plates) to cholangiole to bile duct to hepatic duct to CBD

28
Q

liver turnover

A

turnover of hepatocytes every 150 days. 1 mitosis every 20 000 cells. at surgical excision, liver will reginirate until normal size

29
Q

consequence of repeated damage to hepatocytes (like drinking all the time)

A

proliferation of CT: called cirrhosis

30
Q

Kupffer cell location

A

flat bulky cell attached to surface of hepatocytes and endothelial cells

31
Q

main components of pancreas

A

endocrine glands: islet of Langerhans

exocrine: compound acinar gland similar to parotid gland

32
Q

exocrine pancreas produces what

A

alkaline fluid and proteins (15 or more zymoens) to digest any macromolecule

33
Q

why pancreas looks like salivary glands

A

both derived from evaginations of the endodermal lining of the embryonic intestine

34
Q

2 important pathologies of the pancreas

A

cancer, pancreatitis

35
Q

how pancreas forms glands (if cut a portion)

A
  • blind ended tubes lined by undiff simple columnar epithelium undergo sequential branching
  • epith organizes in acini and lobules
  • islets of Langerhans get formed by some cells of SEROUS acini
36
Q

what cells of pancreas may be involved in pancreatic cancer

A

the undifferentiated cells of serous acini that form the islets of Langerhans

37
Q

divisions of ducts in pancreas (smaller to bigger) (are divided by CT)

A
  • acinus
  • intercalated duct
  • intralobular duct
  • interlobular duct
  • interlobar duct
  • main pancreatic duct
38
Q

hilum of the pancreas

A

major papilla the ducts merge

39
Q

charact of interlobular duct

A
  • lined by columnar cells
  • lot of CT around them
  • arterioles and venules in the CT
40
Q

charact of intercalated ducts

A
  • lined by cuboidal cells
  • are connected to exocrine cells
  • centroacinar cells are part of the duct system
41
Q

islets of langerhans charact

A
  • large number of capillaries and secretory cells

- surrounded by thin layer of CT and reticular fibers

42
Q

charact of serous acinus

A
  • intercalated duct coming in, centroacinal cells (no zymogen granules
  • acinar cells nuclei at base, have zymogenic granules
43
Q

serous acinar cells on EM

A
  • rough ER, many cisternae and RER, many mts, Golgi forms granules with enzymes from RER.
  • granules open at level of lumen
44
Q

pancreatitis pathophgy

A

tight junctions between acinar cells are disrupted and enzymes reach the CT

45
Q

what regulates the exocrine pancreas

A
  • secretin stims H2O and bicarb secretions (high water low enzyme)
  • CCK (enteroendocrine cells of duodenum) promotes exocytosis of zymogenic granules
46
Q

proenzymes released by zymogenic granules of pancreas and what activates them

A
  • trypsinogen
  • pro-carboxypeptidase
  • pro-elastase
  • pro-phospholipase-A
  • activated by enterokinase in glycocalyx of SI microvilli
47
Q

active enzymes released by acinar cells of pancreas

A
  • lipase
  • amylase
  • RNAse
  • DNAse
48
Q

protective mechanisms in pancreas acini

A
  • tight junctions to protect from lipase

- trypsin inhibitor made by centroacinar cells

49
Q

alpha vs beta cells charact in islets

A

alpha: acidophilic (make glucagon)
beta: pale and don’t stain well (make insulin)

50
Q

how to diff pancreas and parotid gland

A

presence of islets of langerhans = pancreas

51
Q

glucagon (alpha cells) charact

A

15% of islet. big cells. on periphery of islet. glucagon promotes glycogen breakdoen and GNG to maintain basal glycemia

52
Q

how to stain for alph cells

A

Ab to glucagon

53
Q

glucagon charact

A
  • single polypeptide chain
  • very conserved across species
  • some endocrine cells may produce a glucagon-like peptide
54
Q

beta cells charact

A

70% of islets. in all islet. are small. insulin for glucose uptake and reduce glycemia

55
Q

how to see beta cells on histo

A

stain with Ab to insulin

56
Q

steps of insulin synthesis

A
  • single polypeptide chain (N term - B chain - C chain - A chain - C term) with S bonds between B and A chain
  • cathepsin E removes the C chain to leave 2 chains B and A linked by S bonds
57
Q

how islet cells do endocrine secretion

A
  • RER, golgi, secretory vesicles

- insulin and glucagon go to fenestrated capillaries

58
Q

other cell types in islets of Langerhans

A
  • delta cells

- PP cells

59
Q

delta cells charact

A
  • 5% of islet
  • large
  • everywhere in islet
  • make sts (inhibits glucagon AND insulin secretion + inhibits HCl secretion by parietal cells)
60
Q

PP cells charact

A
  • 1% of islet
  • large
  • everywhere in islet
  • make pancreatic polypeptide (a hormone that stimulates the secretion of pepsinogen by chief cells
61
Q

acute pancreatitis pathophgy

A

chronic ingestion of alcohol causes it (obstruction of duct system, activation of trypsin, release of enzymes in IC space)

62
Q

type 1 DM pathophgy

A

before age 15, autoimmune destruction of beta cells of islets

63
Q

pancreatic cancer pathophgy

A

cancer of stem cells of the exocrine pancreas

Bloc E - GI & Metabolism (58 decks)

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