GI Glands Flashcards
1
Q
describe the fxn of liver
A
- produces and secretes most of circulating plasma proteins
- albumins
- lipoproteins (VLDL)
- glycoproteins (haptoglobulin, transferrin)
- prothrombin
- non0immune alpha and beta gloublins
- storage and/or conversion of vitamins (A,D,K) and iron
- degrades drugs and toxins via conjugation and oxidation
2
Q
describe Glisson’s capsule
A
- fibrous CT encloses and subdivides the liver into lobes and lobules
- capsule surrounded by visceral peritoneum except where liver attached to other structures
- Glissons capsule is covered by the mesothelial lining of the peritoneum making the liver intraperitoneal
3
Q
A
4
Q
describe the porta hepatis
A
- the region where the main hepatic artery and the portal vein enter and the hepatic ducts leave the liver
- separates quadrate and caudate lobes of liver
- contrast with portal canal which contains branches of these vessels and found between 2 lobules
5
Q
describe the blood supply of the liver
A
- vascular components of the porta hepatis
- hepatic artery (25%) = fully oxygenated
-
portal veins (75%) = venous blood from intestines, pancreas and spleen
- rich in nutrients, endocrine secretions and blood cell breakdown products
6
Q
describe the venous drainage of the liver
A
- hepatic vein drains most of the blood from the liver
- formed by the union of numerous sublobular veins
- sublobular veins collect blood from the central vein of each class liver lobule
7
Q
describe hepatic sinusoids
A
-
discontinuous endothelium
- numerous large fenestrations without diaphragm
- gaps between endothelial cells
- associated with Kupffer cells (macrophages), which are phagocytic cells from the monocyte lineage
8
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A
9
Q
describe hepatocytes
A
- microvilli on surface of cell
- foamy appearance of cytoplasm due to glycogen
- lipofuscin granules
10
Q
describe the surfaces of the hepatocyte
A
- adjacent neighboring hepatocytes (green)
- form small, tunnel-like bile canaliculi that are special intercellular spaces
- TJs between the hepatocytes
- microvilli extend into the bile canaliculus from each hepatocyte
- adjacent space of Disse (red)
- microvilli assist in the transfer of material to and from hepatocytes
- this is where the endocrine secretion of the liver also takes place
- microvilli assist in the transfer of material to and from hepatocytes
11
Q
A
green = adjacent neighboring hepatocyte
red = space of Disse
12
Q
describe the peri-sinusoidal space (aka the space of Disse)
A
- it is the subendothelial space between the liver cells and the lining cells of the sinusoids
- basal lamina is not present in this space
- function:
- exchange of material b/t the bloodstream and the hepatocytes (which do not contact the bloodstream)
- therefore the adjacent liver surface is specialized for its endocrine functions
- exchange of material b/t the bloodstream and the hepatocytes (which do not contact the bloodstream)
- reticular fibers help maintain the architecture of sinusoids
- un-myelinated nerve fibers
- short, blunt microvilli of hepatocytes
13
Q
what type of cells are found in the perisinusoidal space (of Disse)?
A
- stellate-shaped fat storing cells called Ito cells (which preferentially store vit. A)
- in cirrhosis they play a significant role in fibrogenesis and subsequent portal hypertension
14
Q
A
15
Q
describe bile canaliculi
A
- receive the exocrine secretion of the liver (bile) thus representing the beginning of the duct system
- initial site of biliary tree
- convey bile to canals of Herring which then drain into the bile ductule
16
Q
describe biliary tree
A
- consist of the bile canaliculi (lined by hepatocytes) which travels to:
- canals of Herring (lined by both cuboidal cholangiocytes and hepatocytes), which travel to:
- intrahepatic bile ductules (found in the peri-portal space of Mall and lined by only cuboidal cholangiocytes) which drains into:
- interlobular bile (hepatic) ducts found in the portal triad
- main difference between Canal of Herring and the bile ductule is whether it is completely or partially lined by cholangiocytes
17
Q
describe non-alcoholic fatty liver
A
- fat deposits in the liver without a history of alcohol abuse
- lipid filled cytoplasmic vacuoles very similar to alcoholic fatty liver disease
- associated with obesity, insulin resistance
- most severe form is non-alcoholic steatohepatitis (NASH)
- cirrhosis
- hepatocellular cancer
18
Q
describe liver chirrhosis
A
- changes due to chronic alcohol intake:
- parenchymal injury and consequent fibrosis are diffuse, extending through the liver
- fibrosis is irreversible
- mechanism:
- collagen is deposited in all portions of the lobule
- alterations in the sinusoidal endothelial cells
- net result is severe blood flow disruption and decrease in hepatocyte function
- nodular appearance is due to extensive fibrosis surrounding nodular clusters of healing hepatic tissue
19
Q
describe the hepatobiliary tree
A
- interlobular ducts -> R and L hepatic ducts -> common hepatic duct -> cystic duct which leads to the gallbladder
- the common bile duct delivers its content into the lumen of the duodenum via the ampulla of vater after joining with the main pancreatic duct
20
Q
describe the sphincter of Oddi
A
- proximal to the ampulla of Vater
- formed thickening of the muscularis externa of the duodenum at the ampulla
- regulates the flow of bile and pancreatic juice into the duodenum
21
Q
describe the gallbladder
A
- small, pear-shaped organ
- stores and concentrates bile manufactured by liver
- stores 40-60 mL
- muscle wall contracts to force the bile in its lumen into the duodenum where the bile acts to emulsify fats
- contraction is facilitated by hormone cholecystokinin (secreted by enteroendocrine cells)
22
Q
describe the epithelium of the gallbladder
A
- simple columnar epithelium
- apical microvilli
- junctional complexes at apical surface which form a barrier between the lumen and the intercellular compartment
- mitochondria at basal surface
23
Q
describe the lamina propria and the muscle layer of the gallbladder
A
- lamina propria
- abundant fenestrated capillaries
- highly convoluted in empty gallbladder
- mucous glands proximal to the cystic duct -> abundant in cholecystis
- muscle layer
- think layer of smooth muscle cells oriented in an olbique fashion
24
Q
describe the CT covering of the gallbladder
A
- dense, irregular collagenous, with nerves and blood vessels
25
describe cholelithiasis (gallstones)
* 80% of stones are cholesterol stones
* risk factors = 4 Fs
* advancing age (\>40s)
* females
* fat
* fertile
* clinical presentation:
* symptomatic only if there is blockage
26
describe serous cells
* pyramidal shape
* protein secreting cells
* spherical nucleus
* large amounts of rER, free ribosomes, prominient Olgi
* zymogens at the apical zone with basal or perinuclear organelles
* hence basal basophilia and apical eosinophilia
27
describe mucus cells
* mucin secreing cells
* nucleus flattened at base of cell
* mucinogen granules and large Golgi apparatus apically located
* appears "frothy" and stains weakly with H&E
28
describe intralobular ducts
* intercalated ducts
* smallest ducts
* lined by low cuboidal epi.
* secrete bicarb
* striated ducts
* high cuboidal to columnar lining
* **contain abundant mt in the basal in-foldings**
* reabsorb more Na from primary secretion
29
describe the parotid gland
* **pure serous**, compound, tubuloalveolar gland
* capsule: formed by the superficial cervical fascia -\> collagenous
* secretory portion consists of serous amylase-producing cells that store this enzyme in granules
* granules also contain peroxidase, lysozyme and cytstatins
30
31
describe an excretory duct
* travel in the interlobular and interlobar CT
* epithelium changes from simple columnar to stratified cuboidal/columnar and then turn into stratified squamous epithelium of oral cavity
32
describe Stensen's duct
* largest excretory duct of the parotid gland
33
describe sublingual gland
* mixed, compound tubuloalveolar gland
* mostly mixed units with serous demilunes
* purely serous units **are not present**
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