Liver & Gall bladder Flashcards
(156 cards)
Which veins make up the hepatic portal vein?
- Superior Mesenteric Vein
- Splenic Vein
- Inferior mesenteric
The portal vein carries outflow from?
- ) Spleen
- ) Oesophagus
- ) Stomach
- ) Pancreas
- ) Small and large intestine
How much blood does the hepatic portal vein supply to the liver?
75%
Hepatic Blood Flow
- Oxygenated blood from hepatic artery & nutrient-rich, deoxygenated blood from hepatic portal vein
- –> Liver sinusoids
- –> Central vein
- –> Hepatic vein
- –> IVC
- Right atrium
Portal-caval anastomoses
4 collateral pathways
- Esophageal and gastric venous plexus
- Umbilical vein from the left portal vein to the epigastric venous system
- Retroperitoneal collateral vessels
- Hemorrhoidal venous plexus
What may happen to the portal caval anastomoses?
In portal hypertension, the collateral vessels may become engorged, dilated or varicosed.
May rupture
Normal pressure of the portal vein system?
5-8 mmHg
PORTAL HYPERTENSION
- Pressure above normal range of 5-8mmHg
- Portal vein-hepatic vein pressure gradient greater than 5mmHg
- Represents increase in hydrostatic pressure within portal vein and its tributaries
Portal Hypertension - Causes
- Prehepatic
- Intrahepatic
- Prehepatic -
Blockage of the portal vein before the liver, due to portal vein thrombosis or occlusion secondary to congenital portal venous abnormalities
- Intrahepatic -
Due to distortion of the liver architecture
i. PRESINUSOIDAL - schistosomiasis; non cirrhotic portal hypertension
ii. POSTSINUSOIDAL - cirrhosis, alcoholic hepatitis, congenital hepatic fibrosis
3. Budd-Chiari and veno occlusive disease
Budd-Chiari syndrome
Thrombosis/Occlusion of the hepatic veins draining the liver
> Congenital webs
Thrombotic tendency, protein C or S deficiency
Clinical//
• Acute
– jaundice, tender hepatomegaly
• Chronic
– Ascites
Abdo pain, ascites and liver enlargement
Diagnosis//
– US of hepatic veins
Treatment//
- Recanalisation
- TIPSS
Wilson’s Disease
- Disorder of copper metabolism
- Loss of function or loss of protein mutations in CAERUOPLASMIN
- Copper-binding protein, loss of copper regulation
- massive tissue deposition of copper
Clinical //
- Neurological (involuntary movements)
- Hepatic (cirrhosis)
- KAISER-FLEISCHER Rings
- Basal ganglia degeneration
- Dementia
- Blue nails
- Chromosome 13
Treatment//
copper chelation drugs - PENICILLAMINE
ZINC
Hepatic Carcinogenesis
- Recurrent hepatocyte death
- regeneration
- cellular hyperplasia (recurrent DNA copying)
-INFLAMMATION
degranulation cell cycle control
DNA damage due to ROS & RNS
Cirrhosis
- Compensated
- Decompensated
i) Compensated
- clinically normal
- incidental finding
- lab test/ imaging abnormality
- Portal Hypertension may be present
ii) Decompensated
- Liver Failure > acute on chronic ---infection ---insult ---SIRS > End-stage liver disease --- insufficient hepatocytes ---"run out of liver"
What happens in the liver sinusoids?
Arterial and venous blood mixes
Route blood takes through the liver?
Hepatic artery and hepatic portal vein –> arterioles and venues –> sinusoids –> central vein of liver lobule –> branches of hepatic vein –> hepatic vein
Features of liver lobules
- Hexagonal
- Has a branch of hepatic vein at its centre (central vein)
- Has a triad at each of its six corners with branches of hepatic portal vein, hepatic artery and bile duct
- Cords of hepatocytes arranged as hepatic plates
- BLOOD flows INWARDLY through sinusoids to the central vein
- Bile flows OUTWARDLY through canaliculli to the bile duct
How are HEPATOCYTES arranged?
Arranged in between sinusoids in plates two cells thick
- BASOLATERAL membrane faces the SPACE OF DISSE (extracellular gap between the latter and the endothelial cells that line the fenestrated sinusoids)
- APICAL membrane of adjacent hepatocytes is grooved and forms the canaliculli
What do SINUSOIDAL SPACES contain?
> Endothelial cells
- form a fenestrated structure, allowing for free movement of solutes
> Kuppfer cells
- macrophages resident to the sinusoidal space, remove particulate matter and senescent erythrocytes
> Stellate (Ito) cells
- within the space of Disse
- important for vitamin A storage
Intrahepatic Bile System
Canaliculi -> terminal bile ductules -> perilobular ducts -> interlobular ducts -> septal ducts -> lobar ducts -> two hepatic ducts -> the common hepatic duct
Bile production between meals
Stored and concentrated in the gall bladder (sphincter of Oddi closed)
Bile production DURING a meal
- Chyme in duodenum stimulates gall bladder smooth muscle to contract
- Sphincter of Oddi opens
- Bile spurts into duodenum via cystic and common bile ducts
- Digestion and absorption of fat
How does gall bladder contract, and the sphincter of oddi open?
CCK and vagal impulses
Bile from Bile Duct Cells
Alkaline, HCO3 rich
Between meals has an ionic composition
neutralisation of chyme
pH adjustment for enzyme action
mucosal protection
Bile from HEPATOCYTES
> secreted into canaliculli > Primary bile acids - CHOLIC and CHENODEOXYCHOLIC acids > Water and electrolytes > Lipids and phospholipids > Cholesterol > IgA > Bilirubin