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Flashcards in Liver, gall bladder, pancreas Deck (28)
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1

Liver Connective tisssue (small amount):

- Glisson capsule
- reticular fibers (perisinusoidal space and around the central vein)
- fibroblasts and collagen around the portal triads

2

Liver Vascular System

Interlobular vessels in triads (blood directed toward the sinusoids)
- portal vein 75% (blood from intestine, spleen, pancreas)
- hepatic artery 25% (oxygenated blood to the liver)
-central vein – travels alone (receives blood from the sinusoids

3

Hepatic microcirculation

Liver sinusoids are thin, discontinuous capillaries (gaps present), lined with the endothelial cells.

4

Liver: cells

hepatocytes, hepatic stellate cells, kupffer cells, endothelial clls

5

Hepatocytes:

large, polygonal cells, acidophilic, one nucleus or binucleated, deposits: glycogen, lipids;
-synthesized proteins and lipoproteins transferred into the blood (endocrine secretion)
-storage of pigment lipofuscin (lysosomes)
-degradation of toxins (sER)

6

Hepatic stellate cells

(in Space of Disse): lipocyte, adipose cell, fat-storing cell, Ito cell; storage site for vitamin A, production of collagen fibers.

7

Kupffer cells (in sinusoids):

breakdown of damaged red blood cells and formation of bilirubin)

8

Endothelial cells: (lining sinusoids):

discontinuous with gaps

9

Liver: Space of Disse

-microvilli of Hepatocytes
-cellular processes of Kupffer cells
-Hepatic stellate cells (Ito cells)
-type III collagen fibers (reticular fibers)
-Endothelial cells

10

Reticular fibers around sinusoids in the

liver unit

11

Cirrhosis

(diffuse condition of the liver associated with progressive fibrosis),
Ito cells transform into myofibroblasts and produce high level of collagen.
Cytokines produced by hepatocytes, Kupffer cells, infiltrating lymphocytes stimulate production of collagen type I.
Collagen type I deposited in the Space of Disse results in fibrosis and alteration of the portal venous blood flow.

12

Endocrine Liver

secretion into the sinusoids

13

Exocrine Liver

secretion into the bile canaliculi

14

Liver ducts

-Bile ductule, interlobular bile ducts in portal triads (cuboidal epithelium),
-Hepatic Bile ducts, common bile duct (columnar epithelium with microvili),
-Cystic duct

15

Liver portal triad

bile duct, hepatic artery, portal vein

16

liver structure: Classic lobule:

hexagonal, its axis: central vein, its poles: portal canals

17

liver structure: Portal lobule:

triangular, its axis: interlobular bile duct

18

liver structure: Liver acinus:

eleptical, its axis: distributing vessels, its poles: central veins (Zone 1: first receives nutrients & toxins, Zone 3: last to receives nutrients & toxins)

19

The liver acinus: a functional interpretation of liver organization ZONES

Zone 1 - (the closest to the axis) first to receive nutriens or toxins
Zone 3 – (the closest to the central vein) last to receive nutriens and toxins
Zone 2 – lies in between

20

Clinical Note:
Congestive Heart failure
and Liver Necrosis
(cardiac cirrhosis)

H&E staining of liver biopsy.
The severe pathologic changes
(vacuoles with lipids in Zone 3)
occurring due to not sufficient
oxygenation (ischemic necrosis)

21

GALL BLADDER

concentrates and stores bile, absorption of water and electrolytes

22

bile secreted to the duodenum after

hormonal cholecystokinin – CCK stimulation (from enteroendocrine cells in small intestine) in response to the presence of fat in the duodenum

23

GALL BLADDER characteristics

* mucosa forms folds
* simple columnar epithelium
* apical short microvilli
* lateral plications of epithelium

24

Gallbladder: Clinical Note:
Obstructive billary disease

Gallstones may form in the gallbladder or biliary tree when solid concretions of bile act as a nidus for calcium salt deposition.
-Small gallstones are asymptomatic, larger gallstones can cause obstructive jaundice (obstruction of a bile duct) or cholecystitis (obstruction in the cystic duct) interfering in flow of bile.
-This often results in infection and episodes of pain and fever.

25

Pancreas: Exocrine

serous acinus gland
secretes small volume of fluid, and enzymes, e.g., trypsin, chymotrypsin, amylase (precursors)
-centroacinar cells and intercalated ducts outside of acinus
intercalated ducts add bicarbonate and water (large volume of fluid)
-intralobular collecting ducts
-interlobular ducts – low columnar epithelium, transport secretory products
--main pancretaic duct joins the bile duct enters duodenum

26

hormonal control of pancreas exocrine function by enteroendocrine cells in duodenum:

-seretin – stimulates bicarbonate ion secretion,
-cholecystokinin (CCK) – stimulates enzyme secretion

27

Endocrine Pancreas

Endocrine – Islets of Langerhans (1-2% of pancreas) secretes hormones that regulate blood glucose level
-principal cells: A, B, D, and F
-B cells – 70% of total cells, centrally located secrete insulin (lower blood glucose)
-A cells – 15-20%, peripherally lcated, secrete glucagon (increase blood glucose)
-D cells – 5-10%, peripherally located, secrete somatostatin (inhibit glucagon release by A cells)
-F cells (a few), secrete pancreatic polypeptide

28

Accessory Digestive Organs and Enterocyte (Absorptive Cell) [inside duodenum]

Absorptive cell (Enterocyte) with microvilli contains enzymes (enterokinase) within the cell membrane of microvilli. Enterokinase activates pancreatic proenzymes.