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What is considered the triad in the liver
- Bile duct
- Hepatic artery
- Portal vein
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What is the Hilum of the liver
The site where the Hepatic artery, Portal vein, and Bile duct enter the liver
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What is the blood supply to the liver and what makes it unique
Portal vein carries 75% of the blood to the liver which is deoxygenated, carrying nutrients, and toxins
Hepatic artery carries the other 25% of the blood to the artery which is oxygenated
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What is the blood flow route through the liver
- Portal vein or Hepatic artery
- Sinusoids
- Central vein
- Sublobular vein
- Hepatic vein
- Inferior vena cava
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What is the connective tissue capsule called covering the liver
Glisson's capsule
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What does a hepatic lobule consist of
A six sided polyhedral prism with portal triads at each corner and a central vein in the middle of each lobule
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What is the role of the bile canaliculi
Bile flows from triad into the bile duct between the hepatic cords which make up the bile canaliculi
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What are the Peritubular and Centrilobular lobes
Liver lobule triangular sections consisting of two triads and the central vein, the portion closest to the triad is Perilobular, and the section closest to the central vein is Centrilobular
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What is the significance of the Centrilobular section of the liver lobule
- It is nearest to the central vein and therefore receives the least amount of nutrients (toxins)
- It is also vulnerable to anoxia being the lasts portion to receive oxygen
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What is the significance of the Peritubular region of the liver lobules
This is the region next to the triad and therefore is less prone to anoxia but supplied more by toxins and nutrients coming from the venous blood
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What is the difference between the Portal lobule and the Liver acinus
Portal lobule is a section of the liver lobule characterized by the area between three central veins
Liver acinus is characterized by the area between to adjacent central veins
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What is unique about Hepatocytes
Each perform most of the functions of the liver (equipotential) but may have specialization
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Hepatic sinusoids
Specialized capillaries that carry blood through the liver parenchyma
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What are the three cell types associated with Hepatic sinusoids
- Endothelial cells (fenestrated)
- Kupffer cells
- Stellate cells (Ito cells) fat storing
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Where are the Stellate cells found in the liver
In the space of Disse (between Endothelial cells and the hepatocytes)
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What are Kupffer cells
Cells found lining the sinusoids in liver that are Antigen presenting cells and macrophages
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Bile canaliculi
Space between adjacent hepatocytes sealed by zonula occludens forming Hering's canal where bile travels to the bile ducts
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What is the purpose of the Gall bladder
Serves as a reservoir for bile and functions to concentrate it by removing water
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What layers are found in the Gall bladder
- Mucosa
- Muscularis externa
- Serosa
- (No muscularis mucosa or submucosa)
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An excess in copper stored in the body can cause
- Wilsons disease
- Keyser-Fleischer rings around the eyes are a classic clinical finding
- Parkinsons
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All circulating protein accept which are synthesized by the liver
Gamma-Globulins
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Detoxification in the liver undergoes Phase 1 and Phase 2, what happens in phase 1
(Slow stage) The substance can undergo (P-450) Oxidation, Reduction, or Hydrolysis and is then sent to the kidneys for excretion or to phase 2 for conjugation
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What happens in Phase 2 of detoxification in the liver
(Fast stage) Conjugation, and then the conjugated metabolite is sent to the kidneys for excretion
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In what form is iron stored in the liver
Ferritin
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Apoferritin
A protein in the liver that reversibly binds with iron for later release when needed
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What vitamin is stored in the highest quantity in the liver
- Vitamin A
- Large amounts of B12, K, and D are also stored in the liver
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The liver can store vitamins A, D, and B12 for periods up to
- A - 10 months
- D - 3 to 4 months
- B12 - 1 year
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What is the path that bilirubin takes to be excreted
- RBC's are broken down and bilirubin released
- Bilirubin binds to Albumin and taken to liver
- Liver turns it into bilirubin diglucuronide
- Bacteria in the intestines converts it to Urobilinogen
- Urobilinogen leaves the body through feces and urine, or is recycled to the liver
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What gives urine its characteristic color
Urobilin a derivative of Bilirubin
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Periportal hepatocytes are most active in taking in and secreting
Uptake of Bile salts, Oxygen, and Nutrients and secretion of bile constituents
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What functions are more active in Periportal hepatocytes then in Perivenous
- Oxidation
- Gluconeogenesis
- Glygogen deposition
- Bile salt conjugation
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What functions are most active in Perivenous hepatocytes
- Taking in Drugs and toxins
- Biotransformation
- Glycolysis
- Ketogenesis
- Fat deposition
- Excreting metabolites
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After feeding, glycogen is deposited firstly into what cells in the liver
Periportal hepatocytes
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Periportal cell vs Perivenous hepatocytes
- Periportal hepatocytes are next to the Portal vein
- Perivenous hepatocytes are closer to the Hepatic vein
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Bile formation is made of two fluids made by what two cells
- Hepatocytes (Dependent on Bile acid)
- Ductule cells/Cholangiocyte (constantly formed)
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Hepatocytes in making bile have what two components contributing to its formation
Bile acid independent portion, and a Bile acid dependent portion, the rate secreted is equal to Bile acid available
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An adequate bile flow is dependent on
Bile salts being returned to the liver by the enterohepatic circulation.
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How much bile is secreted a day and how much of that leaves the body through the feces
- 600ml a day
- 5% is lost in the feces, the other 95% is taken back by the portal vein to the liver for reuse
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Enterohepatic circulation
This is the process of Bile acids returning to the liver through the Portal vein after being used in the intestines
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Bile acids are synthesized in hepatocytes from what
Cholesterol
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What are the primary bile acids found in the Duodenum
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What are the secondary bile acids found in the ileum
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How do primary bile acids become secondary bile acids
Primary bile acids are broken down by bacterial enzymes on their way to the ileum forming secondary bile acids
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Reabsorption of secondary bile acids in the intestines is dependent on
Sodium
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What effect does an Ileal resection have on bile salt synthesis
Due to the decrease in bile acid reuptake bile salt synthesis goes up dramatically
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What effect does eating bile acids have on bile acid synthesis
Dramatically decrease it
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Pumping ions into the bile Canaliculi is passive or active
Active - Pushing against a gradient
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What hormones increase Bicarbonate secretion from Cholangiocytes diluting the bile
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As the gallbladder becomes more concentrated what happens to the levels of ions in the bladder
- Na+ and Bile Acid anions increase concentration
- Cl- and HCO3 decrease concentration in the duct
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What hormone inhibits bicarbonate secretion from the Cholangiocytes
Somatostatin
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Most of the gallbladder absorption is caused by active transport of
- Sodium through the gallbladder epithelium, and
- this is followed by secondary absorption of chloride ions, and water
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How are gallbladder salts so concentrated
Sodium/Hydrogen exchange occurs along with water and Cl- leaking out of the lumen to the basal lateral membrane, the bile is impermeable to the lumen wall thus becomes more concentrated
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VIP and Serotonin have what effect on gallbladder concentration
They inhibit the absorption of electrolytes decreasing the gallbladders bile concentration
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What is the difference between Hepatic bile and gallbladder bile
- Hepatic is more concentrated in electrolytes making it less potent
- Gallbladder is more concentrated with organic components making it more potent
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What are the organic components of bile
- Bilirubin
- Cholesterol
- Lecithin
- Bile salts
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What is the effect of CCK on Bile secretion
It relaxes the sphincter of Oddi and contracts the gallbladder for release into the Duodenum
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What is the effect of gallstones floating in the gallbladder
Asymptomatic
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What is the effect of gall stones being stuck in the Ampulla of vater
This can cause damage to the Liver and Pancreas due to the shared duct
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Obstruction of the common bile duct by a gallstone causes
Biliary colic (pain) and jaundice
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