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Final

BIOM 4070 Final: Liver, pancreas, gall bladder

6 Pages
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Department
Biomedical Sciences
Course Code
BIOM 4070
Professor
Brenda L Coomber

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Liver, pancreas, gall bladder
The pancreas
Endocrine and exocrine function
Produces hormones (endocrine) and digestive enzymes
(exocrine)
Covered by CT capsule; CT septa divide parenchyma
(functional part) into poorly-defined lobes
Pancreatic duct empties into duodenum at hepatopancreatic
ampulla
Compound serous acinar gland
Patches of endocrine islets embedded in acini *completely separate
No duct portion secrete hormones into circulatory system
Exocrine component
Serous cells make up acini
Pyramidal in shape and polarized
Nuclei towards basal surface,
making lots of protein
(enzymes), rich in RER
basophilic
Eosinophilic apical surface,
storing lots of protein to be
secreted via exocytosis
Central lumen
Centroacinar cells
Middle of lumen (hard to see)
Add sodium, bicarbonate & water to secretion
Each acinus has basal lamina supported by reticular CT, very vascular
Intercalated duct (simple cuboidal) merge with larger ducts (columnar) and
eventually join pancreatic duct
Secretion stimulated by hormones (cholecystokinin & secretin) produced by
enteroendocrine cells of duodenum
Won’t release zymogens unless food is present
Pancreas makes & releases enzymes in the inactive form (zymogens) so as not to
digest its own tissue
Example: trypsin
Enteropeptidase (trypsin activator) is only in duodenum
Trypsin inhibitor is packaged with trypsinogen (zymogen)
pH in acini and duct system is not optimal for trypsin activation
(due to HCO3- secreted by centroacinar cells)
centroacinar cell
intercalated
duct
Enzymes
Proteolytic endopeptidases and exopeptidases protein
Amylolytic enzymes carbohydrates
Lipases lipids
Nucleolytic enzymes DNA
Pancreatic problems
Acute pancreatitis
Sudden onset
Zymogens activated in pancreases & digest pancreatic tissue
Caused by excess alcohol, infection, drugs, trauma (gallstones)
Chronic pancreatitis
Gradual onset, recurring
Progressive fibrosis (too much CT, replaces acini with scar tissue), loss of
function, can’t make enzymes or hormones, can lead to diabetes
Caused by excess alcohol, autoimmunity, gallstones, cystic fibrosis
The liver
Divided grossly and functionally into lobules
Covered by CT capsule & peritoneum (made of mesothelium)
Capsule thickens at hilum
Portal vein, hepatic artery, hepatic vein, & common bile duct exit
Functions
Produce bile: emulsification, hydrolysis, & uptake of fats
Interface between digestive system and blood nutrients!
Synthesis of plasma proteins
Detoxification of xenobiotics (foreign)
CT = reticular fibers (collagen III)
Lobule boundaries & support sinusoids
More CT at periphery (where portal triads are)
Blood system
Two sources of input
Hepatic artery: branch off aorta (O2 rich, nutrient poor), 25%
Portal vein: from stomach, spleen, intestines (nutrient rich, may contain
waste), 75%
One source of output
Hepatic veins: central venule from each lobule empty into hepatic veins,
empty into IVC
Sinusoids (discontinuous) travel between layers of hepatocytes, blood from both
inputs mixes here
Blood flows from out in (portal triad central venule)

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Description
Liver, pancreas, gall bladder The pancreas  Endocrine and exocrine function  Produces hormones (endocrine) and digestive enzymes (exocrine)  Covered by CT capsule; CT septa divide parenchyma (functional part) into poorly-defined lobes  Pancreatic duct empties into duodenum at hepatopancreatic ampulla  Compound serous acinar gland  Patches of endocrine islets embedded in acini *completely separate  No duct portion – secrete hormones into circulatory system Exocrine component  Serous cells make up acini  Pyramidal in shape and polarized  Nuclei towards basal surface, making lots of protein intercalated (enzymes), rich in RER  duct centroacinar cell basophilic  Eosinophilic apical surface, storing lots of protein to be secreted via exocytosis  Central lumen  Centroacinar cells  Middle of lumen (hard to see)  Add sodium, bicarbonate & water to secretion  Each acinus has basal lamina supported by reticular CT, very vascular  Intercalated duct (simple cuboidal) merge with larger ducts (columnar) and eventually join pancreatic duct  Secretion stimulated by hormones (cholecystokinin & secretin) produced by enteroendocrine cells of duodenum  Won’t release zymogens unless food is present  Pancreas makes & releases enzymes in the inactive form (zymogens) so as not to digest its own tissue  Example: trypsin  Enteropeptidase (trypsin activator) is only in duodenum  Trypsin inhibitor is packaged with trypsinogen (zymogen)  pH in acini and duct system is not optimal for trypsin activation (due to HCO s3creted by centroacinar cells) Enzymes  Proteolytic endopeptidases and exopeptidases  protein  Amylolytic enzymes  carbohydrates  Lipases  lipids  Nucleolytic enzymes  DNA Pancreatic problems  Acute pancreatitis  Sudden onset  Zymogens activated in pancreases & digest pancreatic tissue  Caused by excess alcohol, infection, drugs, trauma (gallstones)  Chronic pancreatitis  Gradual onset, recurring  Progressive fibrosis (too much CT, replaces acini with scar tissue), loss of function, can’t make enzymes or hormones, can lead to diabetes  Caused by excess alcohol, autoimmunity, gallstones, cystic fibrosis The liver  Divided grossly and functionally into lobules  Covered by CT capsule & peritoneum (made of mesothelium)  Capsule thickens at hilum  Portal vein, hepatic artery, hepatic vein, & common bile duct exit  Functions  Produce bile: emulsification, hydrolysis, & uptake of fats  Interface between digestive system and blood  nutrients!  Synthesis of plasma proteins  Detoxification of xenobiotics (foreign)  CT = reticular fibers (collagen III)  Lobule boundaries & support sinusoids  More CT at periphery (where portal triads are) Blood system  Two sources of input  Hepatic artery: branch off aorta (O 2ich, nutrient poor), 25%  Portal vein: from stomach, spleen, intestines (nutrient rich, may contain waste), 75%  One source of output  Hepatic veins: central venule from each lobule empty into hepatic veins, empty into IVC  Sinusoids (discontinuous) travel between layers of hepatocytes, blood from both inputs mixes here  Blood flows from out  in (portal triad  central venule) Portal triad  Bile ductile  Venule from portal vein  Arteriole from hepatic artery  May also be lymph vessel Hepatocytes  Polyhedral epithelial cells  Large central nucleus (may be bi-nucleated)  Eosiniphilic  lots of mitochondria Function  Synthesis & endocrine secretion of plasma proteins (albumin, fibrinogen…)  Gluconeogenesis  Detoxification of drugs & toxins  Deamination of amino acids into urea  Store glucose as glycogen & store triglycerides as lipid droplets  Store iron with ferritin  Vitamin D & K conversion Ultrastructure  Lots of ER and mitochondria (notice lots of organelles in EM)  Stored nutrients in cytoplasm  Lateral surfaces associated with sinusoids  Perisinusoidal space (space of Disse): between basal surface of sinusoid endothelium and hepatocyte surface  Blood on periphery is most nutrient rich (things taken up as it trickles through)  Apical surfaces of cells held together by desmosomes and tight junctions  Grooves in walls of hepatocytes line up with adjacent grooves to form bile canaliculi; secrete bile into these tiny channels Bile  Bile salts, electrolytes, fatty acids, phospholipids, cholesterol, iron, copper, bilirubin (broken down hemoglobin)  Bile flows in the opposite direction to blood (inout)  Many canaliculi join to form bile canals into bile ductules (in portal triad)  Bile canals lined with cuboidal or columnar epithelium called cholangiocytes  Bile ductules  large bile ducts  hepatic ducts  common bile duct  gall bladder (where bile is stored until needed) Additional Liver Cells Kupffer cells: • stellate macrophages usually found within sinusoid lining Kupffer cells • recognize & phagocytize aged  Star-like macrophages in sinusoid lining erythrocytes: frees heme & iron  Phagocytose old RBC’s to release hemoglobin and iron for reuse or storage in ferritin complexes  Remove bacteria/debris in portal blood • remove bacteria/debris present  APC to immune system in portal blood • antigen presentation to immune system Ito cells/hepatic stellate cells  Mesenchymal cells (multipotent stem cells) with lipid droplets Ito (hepatic stellate) cells:  In perisinusoidal space • mesenchymal cells with small lipid droplets  Store vitamin A and fat soluble vitamins found within perisinusoidal space  Produce ECM components • store vitamin A & other fat soluble vitamins  Role in fibrosis • produce ECM components (role in fibrosis)  Produce cytokines that regulate Kupffer cells
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