Session 7 - Notes Flashcards
• Name three virus’ that are resistant to stomach acid
o Hepatitis A
o Polio
o Coxsackie
• Where are Kupffer cells and what role do they perform?
Kupffer cells are specialised macrophages that reside in walls of the Hepatic sinusoids. They play a role in promoting normal Liver physiology and homeostasis but also participate in the Livers response to toxic compounds. When activated they release a wide range of inflammatory mediators. These macrophages play an important role in the response to ethanol induced Liver damage.
• Define the term cirrhosis listing three characteristic features.
In essence this is necrosis of the hepatocytes in the Liver. Following this destruction, nodules form in the liver and these are separated by fibrotic tissue. The whole process is diffuse and irreversible. The liver firstly enlarges in a phase called acute fatty liver (steatosis) followed by
(1) Chronic hepatocyte necrosis
(2) Chronic inflammation leading to fibrosis
(3) Nodule formation following hepatocyte necrosis
What is actual liver funciton measured by?
Serum Albumin -
Bilirubin
Glucose
Prothrombin time
Why is albumin measured in LFT?
Albumin is produced exclusively by the Liver, so lower measureable levels suggest Liver damage.
Why is bilirubin measured in LFT?
Bilirubin is removed from the blood by the Liver. Raised Plasma Bilirubin suggests a problem with the normal clearance mechanism. This does not necessarily implicate direct Liver damage though.
Why is glucose measured in LFT?
As Gluconeogenesis occurs in the Liver, Liver failure will have an effect on glucose levels. This is quite a late and non specific finding.
Why is prothrombin time measured in LFT?
The Liver produces coagulation factors so Liver damage will have an effect on the bodies ability to clot. Damage can result in an increased clotting times.
• Comparing Hepatitis B and Hepatitis C, discuss two similarities and two differences.
Similarities- Same route of infection. Contaminated blood and body fluids (via several routes). Both can become chronic Infections.
Differences- Hep C generally has a shorter incubation period (6-8 weeks) while Hep B’s is longer (2-6 months). Hep C is much more likely to become chronic in adults (60-90% chance vs 5-10%)
You can be vaccinated against Hep B but not Hep C
• Jane wishes to know what treatment might be available if she has either Hep B or C diseases. Discuss what options exist and the side effects.
Alpha interferon is one treatment for Hep B and C. Use of the antivirals Ribavirin and lamivudine can be used to reduce viral load. SE for these drugs include almost everything, but commonly fatigue and loss of appetite.
• If Jane does have either Hepatitis B or C but decides against treatment, what are the possible long term outcomes?
Chronicity of infection possibly leading to cirrhosis or Hepatocellular carcinoma
• Explain the terms “hepatic lobule” and “hepatic acinus”
Hepatic lobule” is a concept based upon organization of the hepatic paranchymal cells (hepatocytes) around the liver vascular elements. The classic hepatic lobule has a tributary of a hepatic vein (called the central vein) at its central axis with the portal triads at its periphery; each portal triad consists of a branch of the hepatic portal vein (portal venule), a branch of the hepatic artery (hepatic arteriole) and an element of the intrahepatic biliary system (bile duct/ductule).
“Hepatic acinus” is another concept based on functional parameters; this concept is favoured on metabolic and pathologic considerations. The hepatic acinus is an elliptical area with a short axis spanning two portal triads and a long axis defined by a line drawn between two central veins that form the outermost poles of the acinus. The short axis contains the portal venules and hepatic arterioles, both of which drain directly into the hepatic sinusoids lying between the hepatocytes. The sinusoids empty into the “central veins” which are now designated as “terminal hepatic venules” since they no longer are considered to be central in location.
• Which other structures derive arterial blood supply from the hepatic artery?
Hepatic artery gives off the cystic artery that supplies the cystic duct, the gall bladder and the common bile duct.
• What structural feature of bile acids enables them to emulsify fat?
Bile acids are facial amphipathic, that is, they contain both hydrophobic (lipid soluble) and polar (hydrophilic) faces. The cholesterol-derived portion of a bile acid has one face that is hydrophobic (that with methyl groups) and one that is hydrophilic (that with the hydroxyl groups); the amino acid conjugate is polar and hydrophilic.
Their amphipathic nature enables bile acids to carry out two important functions:
• Emulsification of lipid aggregates: Bile acids have detergent action on particles of dietary fat which causes fat globules to break down or be emulsified into minute, microscopic droplets. Emulsification is not digestion per se, but is of importance because it greatly increases the surface area of fat, making it available for digestion by lipases, which cannot access the inside of lipid droplets.
• Solubilization and transport of lipids in an aqueous environment: Bile acids are lipid carriers and are able to solubilize many lipids by forming micelles - aggregates of lipids such as fatty acids, cholesterol and monoglycerides - that remain suspended in water.
• List four major functions of the Liver
o Energy metabolism
o Detoxification
o Production/secretion of Bile
Plasma protein production
