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GI test 2 > Histo: liver/gallbladder > Flashcards

Histo: liver/gallbladder Flashcards

1
Q

liver peritoneum?

A

simple squamous epithelium

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2
Q

portal system of liver?

A

systemic capillaries –> veins –> portal vein –> venules –> capillaries –> venules –> small veins –> hepatic v –> IVC

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3
Q

hepatic triad?

A

portal vein, hepatic artery, bile ductule, lymph vessel

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4
Q

liver lobule?

A

blood enters at periphery of lobule, percolates via sinusoids through the lobule and leaves via the central vein.
- bile travels counter-current and leaves at periphery of lobule

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5
Q

Muralium

A

= walls of hepatocytes, which radiate around the central vein and form the vascular sinusoidal channels where the blood drains to reach back to the central vein.

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6
Q

hepatocytes

A
  • large mono/binucleated cells that are often polypoloid
  • forms simple muralium
  • 3 surfaces where it comes into contact
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7
Q

3 surfaces in contact with sinusoids

A
  1. sinusoidal: a cellular gap that is discontinuous capillary eptihelium with gaps between cells that allows trafficking b/w capillary and hepatocytes - capillaries are surrounded by “space of Disse”
  2. basolateral surface: where hepatocytes encounter other hepatocytes
  3. canalicular surcae: small channel where bile is carried to duct system b/w adjacent hepatocytes
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8
Q

hepatic sinusoids

A

A liver sinusoid is a type of blood vessel (with discontinuous basal lamina) that serves as a location for the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein

Hepatocytes are separated from the sinusoids by the space of Disse.

Kupffer cells are located inside the sinusoids and can take up and destroy foreign material such as bacteria.

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9
Q

Liver stroma

A

“scaffolding of liver cells” - supported by the vessels and reticular fibers

  • stroma is altered in diseases such as hepatic fibrosis and hepatic cirrhosis - where the CT elements increase in the parenchyma
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10
Q

3 types of liver lobules?

A

classic: endocrine
portal lobule: exocrine
portal acinus: acinar lobule based on metabolic zonation

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11
Q

classic lobule

A

endocrine- secretion of hormones into bloodstream

  • polygonal shape with portal canals at periphery and veins at the center
  • products synthesized and secreted into blood & used elsewhere: fibrinogen, albumin, glucose
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12
Q

portal lobule

A

exocrine: secretion of products into ducts
- triangular shape with portal canal in center and central vein at peripheral apices
- synthesizes and secretes bile into a duct

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13
Q

Portal acinus

A

“acinar lobule” or “Rappaport’s lobule”

  • oblong/oval shaped running fro central vein to central vein length wise, and portal triad to portal triad
  • refelects gradient of metabolic activity in the liver
  • useful in describing hepatic regeneration, development of cirrhosis, centro-lobular necrosis
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14
Q

Zones of portal acinus

A

zone 1 (periportal zone):receives blood with highest concentration of nutrients/oxygen. last to die and first to regenerate. more metabolism happens here.

zone 2 (mid-region):receives blood of intermediate “quality“ (from zone 1)

zone 3 (centrolobular zone): receives blood with lowest nutrient/oxygen content (from zone 2). first cells to die in centrolobular necrosis

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15
Q

hepatectomy

A
  • liver holds great capacity for regeneration

- if liver lobule taken, hepatocytes of all zones will regnerate and liver will recover, due to polypoloidy nature

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16
Q

zonal damage

A

seen in pathology, such as hepatic cirrhosis: selective regeneration of damaged zones as opposed to regeneration in all zones

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17
Q

hepatic cirrhosis

A

abnormal regeneration due to CT elements not cooperating –> altered hepatic structure and compromised parenchymal function

18
Q

mitochondria

A

many in hepatocytes
1000-2000 per cell
self-replicating by budding
function in : ox phos, urea cycle, TCA, lipid oxid.

19
Q

lysosomes

A

function in catabolism (breaking down) of substances
- autophagy = internal structures
- heterophagy = external substances
low pH of 4-5 maintained via proton pump
- enyzmes synthesized in rER and transported to Golgi
- receptor–ligand complexes turned over in lysosome
- liver is target for numerous hormones endocrine receptors: growth hormone, prolactin, insulin, glucagon, NE.

20
Q

lysosomal disease

A
  • absence of specific lysosomal enzyme
  • often affects lipid production
    ex. Tay-Sachs disease, metachromatic leukodystrophy, type II glycogenesis
21
Q

rER and golgi

A

plasma proteins (albumin, prothrombin, fibrinogen etc.) are synthesized on rough endoplasmic reticulum. Proteins pass through Golgi not stored secretion granules in liver. proteins are secreted in small clear vesicles

VLDL (very low density lipoproteins) transport
apoprotein for lipoproteins is synthesized in rER
complete formation of VLDL requires sER to converted from chylomicrons

22
Q

smooth ER

A

synthesizes cholesterol and phospholipids

  • esterification of FFA –> triglycerides
  • detoxification/metabolism of drugs
23
Q

glycogen

A

stored in rosettes around sER

- enzymes for glycogenolysis are membrane bound

24
Q

peroxisomes

A
  • degradatory membrane bound microbodies

- oxidize substrates using molecular O2 and H2O2

25
Q

cytoskeletal elements of hepatocytes

A

Microtubules: vesicular transport

Microfilaments: important in bile flow. submembranous and pericannilicular location

Intermediate filaments: submembranous and pericannilicular location. seen in variety of hepatic diseases e.g. cirrhosis & cholestatic conditions

26
Q

hepatic sinusoids

A

discontinuous wall with gaps b/w adjacent cells of basal lamina

  • allows easy access of blood to hepatocytes
  • excludes cellular elements from space of Disse
27
Q

non-hepatocyte sinusoidal cells

A 
endothelial cells (fenestrated)
Kupffer cells (mono-nuclear phagocytes)
fibroblasts
lipocyte (Ito cell)
hematopoetic cells during fetal life
28
Q

endothelial cells

A 
(48% of cells)
fenestrated, and w/o diaphragms in humans
no pericytes
basal lamina indistinct
type IV collagen and laminin detectable
29
Q

fibroblasts

A

reticular fiber synthesis with type III collagen

30
Q

Kupffer cells

A

fixed macrophage of sinusoids (40% of cells)

  • have Fc and C’ receptors on their surface
  • phagocytose immune complexes, bacteria, non-immune particulates
  • bind & degrade hemoglobin to bilirubin: shared function with splenic phagocytes
  • highly toxic in high (unbound) concentrations
  • transported to hepatocyte for further processing
  • can take over RBC degradation function of the spleen
  • processes & presents antigen
31
Q

Ito cells

A

hepatic lipocyte (fat cell) ~10% of non-hepatocyte cell
lipid droplets characteristic feature
- vitamin A rapidly taken up and stored in lipid droplet
- take up lipophylic/membranolytic molecules which damage lysosomes

32
Q

bile

A
  • necessary for solubilization/absorption of intestinal fat
  • provides main pathway for excretion of cholesterol
  • eliminates many toxins, including bilirubin
  • constituents of bile include: electrolytes (Na+,K+,Ca2+,Mg2+,Cl-,HCO3-), bile acids, cholesterol conjugates, bilirubin-glucuronide
33
Q

flow of bile

A

intrahepatic channels: bile canaliculus –> terminal ductules –> interlobular bile ducts –>

extrahepatic ducts: (right/left hepatic ducts –> proper hepatic duct –> cystic duct –> common bile duct)

34
Q

bile canaliculus

A
  • sealed by zonula occludens & desmosomes

- Golgi & sER oriented toward bile canaliculus

35
Q

terminal ductules

A

transition from canaliculus to interlobular bile ducts

  • basal surface attached to hepatocytes
  • flattened to cuboidal epithelium
  • bicarbonate-secreting pinocytotic vesicles modify bile
36
Q

interlobular bile ducts

A

cuboidal to columnar epithelium

  • surrounded by elastic and collagen connective tissue
  • may modify bile by additional bicarbonate secretion
  • surrounded by smooth muscle at porta hepatis
  • narrowing of ducts
37
Q

extrahepatic bile ducts

A

(right, left, proper hepatic ducts

  • tall columnar cells with occasional mucous cells
  • general plan similar to gut: (mucosa, submucosa, muscularis, adventia)
38
Q

cystic duct

A

emerges from gallbladder neck

  • neck twists, throwing spiral fold into mucosa
  • folding persists in cystic duct
39
Q

common bile duct

A

structure of duct is similar to hepatic ducts

-difference: circumferential smooth muscle sphincter present - known as sphincter of Boyden- located prior to junction with pancreatic duct

40
Q

gallbladder

A

filled: surface even
empty: decussating folds/ruggae

Mucosa:

  • simple columnar epithelium with microvili (suggest absorptive purpose - extracts water, inorganic salts and electrolytes)
  • Rokintansky-Aschoff Crypts (invaginations increasing surface area)
  • mucous glands (at neck of gallbladder)
Lamina Propria: 
thin layer of dense irregular CT
-numerous small blood vessels
-numerous small lymphatic vessels
-no muscularis mucosa

NO SUBMUCOSA IN GALL BLADDER

Tunica Muscularis: smooth muscle layer with some collagen and elastic fibers

Serosa: thick layer of dense irregular CT with vv. and lymphatics

41
Q

Secretin, CCK

A

secretory stimulus from gut enteroendocrine cell

  • secretin - induces biliary bicarbonate and H20 secretion
  • cholecystokinin (CCK ) - induces gall bladder contraction

GI test 2 (14 decks)

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