Term
| What are the 6 primary functions of the liver? |
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Definition
1) Blood glucose regulation
- Insulin promotes glycogen storage and glucagon promotes glycogenolysis and gluconeogenesis from body protein (only organ that can do BOTH)
2) Lipid metabolism
- Synthesis of cholesterol, bile (secreted into intestine) and fatty acid metabolism (VLDL packaging)
3) Protein metabolism/Plasma protein
- Synthesis of albumin and most other plasma proteins
- AA metabolism (transaminases) in gluconeogenesis
4) Detoxificaiton
- CYP enzymes solubilize foreign substances and allow their excretion through bile into small intestine (ethanol and barbiturates).
5) Vitamin metabolism
- ADEK and B12
6) Excretion (blood filtering)
- Aging RBCs phagocytosed by macrophages (Kupffer cells) in liver sinusoids
- Heme waste product, billirubin, secreted into bile for excretion. |
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Term
| Which 2 organs can perform gluconeogenesis? |
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Definition
Liver and Kidney
Liver ONLY can perform glycogen storage AND gluconeogenesis. |
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Term
| What is the basic blood supply of the liver? |
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Definition
Dual Supply
1) Portal Venous
- Stomach, intestines, pancreas and spleen join to form portal vein that enters base of liver (70%)
2) Hepatic artery (from celiac trunk)
- Systemic arterial blood (30%)
3) Venous drainage by hepatic vein. |
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Term
| What is the structure of a liver lobule? |
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Definition
Polyhedral prism with 6 portal triads at the angles of the hexagon.
1) Each portal triad contains 3 items
- portal vein
- hepatic artery
- multiple cuts of bile ducts (may also see lymphatics)
2) Incoming blood mixes together at periphery (artery and portal vein) and moves through sinusoids towards central vein at center of lobule.
3) Hepatic sinusoids and hepatocytes are separated by Space of Disse, which contains lymph fluid, collagen III and stellate (Ito) cells. |
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Term
| What is the function of stellate (Ito) cells in the liver? |
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Definition
Immune reactions involved in fibrotic changes that take place in cirrhosis and hepatitis.
These cells are found with reticular collagen III and lymph fluid in the space of Disse, which separates hepatocytes from the overlaying sinusoidal capillary endothelium in a liver lobule.
- Store Vitamin A in lipid droplets
- serve as APCs during immune reactions and can create fibrosis of diseases like cirrhosis and hepatitis. |
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Term
| What is the function of hepatic Kupffer cells? |
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Definition
Macrophages that migrate freely in sinusoidal spaces.
- phagocytose aging RBCs for excretion, producing heme waste product billirubin. |
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Term
| How is bile produced, stored and secreted? |
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Definition
1) Synthesized in liver hepatocytes, secreted into bile canaliculi and transported through hepatic duct to cystic duct and into gallbladder
2) Bile stored in liver until stimulated a stimulus like CCK
3) Bile exits gallbladder through cystic duct, passing through the common bile duct and fusing with the pancreatic duct on its way to emptying into the duodenum via the sphincter of Oddi |
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Term
| What classic features characterize a hepatocyte? |
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Definition
Extract oxygen, nutrients and toxins from sinusoidal blood, and secrete plasma proteins, lipoproteins and glucose
1) Multiple apical (canalicular) and basal (sinusoidal) faces
2) Smooth ER for lipid, cholesterol and bile synthesis
3) Glycogen granules for glucose storage |
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Term
| Why might the gall bladder epithelium appear in a "swelled" state under physiological conditions? |
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Definition
Remember, you find simple cuboidal epithelium here.
Extracted water to concentrate bile (main function of gall bladder) |
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Term
| What is the basic structure of the pancreas? |
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Definition
1) Endocrine (Islets of Langerhans)
2) Exocrine (Salivary gland organization)
- Secretory acini (all serous) empty into small, medium and large excretory ducts and into the duodenum
- Secrete digestive enzymes (trypsinogen, chymotrypsinogen, amylase, lipase, ect) and Bicarbonate (only from centroacinar cells). |
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Term
| Explain the structure of a hepatic cord? |
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Definition
- Stacks of hepatocytes (one layer thick) touching one another at apical faces where bile canaliculi are found and sealed off from the extracellular environment by tight junctions.
- Basal faces are adjacent to sinusoids, which contain 'true' fenestrations for lipid and plasma protein exchange. |
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Term
| Explain the structure of a hepatic cord? |
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Definition
- Stacks of hepatocytes (one layer thick) touching one another at apical faces where bile canaliculi are found and sealed off from the extracellular environment by tight junctions.
- Basal faces are adjacent to sinusoids, which contain 'true' fenestrations for lipid and plasma protein exchange. |
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