Jan 29 - Liver Disease: Hepatitis Flashcards
What is the difference between the blood supply to the liver and the other organs?
The liver has two sources where it receives blood: the hepatic artery and the hepatic portal vein. The hepatic artery delivers oxygenated blood from the general circulation. The hepatic portal vein delivers deoxygenated blood from the small intestine containing nutrients (75% of blood flowing through the liver arrives via the hepatic portal vein)
Describe the blood flow through the liver
Blood flows through the liver tissue to the hepatic cells where many metabolic functions take place. The blood drains out of the liver via the hepatic vein. The liver tissue is not vascularized with a capillary network as most other organs; however it consists of blood filled sinusoids surrounding the hepatic cells
What does the liver manufacture?
Albumin, bile, urea and blood proteins
What is albumin?
A protein that regulates the fluid balance in our body’s blood clotting factors
What is bile?
It is used for digestion
How is urea produced?
Deamination of amino acids and conversion of ammonia to urea via the urea cycle
What is the role of blood proteins?
They aid in clotting, oxygen transport and immune system function
What does the liver transform?
Bilirubin, cholesterol, carbohydrates, saturated fats
What is bilirubin?
A pigment released when red blood cells die and becomes a water-soluble substance excreted in the bile
What does the liver do with cholesterol and fatty acids??
It synthesizes cholesterol from acetate, it synthesizes triglycerides from fatty acids. It secretes both in VLDL particles. It takes up cholesterol and triglycerides via endocytosis of HDL and LDL particles, then it excretes cholesterol in bile, beta-oxidizes fatty acids and converts excess acetyl-CoA into ketones
What does the liver do to carbohydrates?
The liver converts sugars into glucose (via gluconeogenesis and glycogenolysis)
It also used glucose for glycogen synthesis, fatty acid synthesis, glycolysis and the tricarboxylic acid cycle
What does liver clean and detoxify?
Bacteria, ammonia, alcohol, both prescription and over the counter drugs, other toxins
What does the liver store?
Glycogen, for energy
Iron
Other vitamins
What are the five functions of the liver?
Energy metabolism and substate interconversion Protein synthesis (clotting factors) Solubilization, transport and storage Detoxification and clearance Bile production
Why does hypoglycemia occur?
Hypoglycemia occurs primarily due to a decrease in “functional hepatocyte mass” (ability to produce and release stored glucose is impaired)
Why does hyperglycemia occur?
Hyperglycemia can occur due to portal-systemic shunt
What are clinical consequences of liver disease?
Hepatocyte dysfunction - manifests as failure of one or more of the main liver functions
Portal hypertension - cirrhosis is often a primary cause, but can also be caused by portal-systemic shunt
What are tests of liver injury?
Aspartate aminotransferase (AST) - indicates hepatocyte death Alanine aminotransferase (ALT) - indicates liver injury Alkaline phosphatase (ALP) - this is also found in the bone, intestine and placenta, which is why GGT is required Gamma glutamyl transpeptidase (GGT) + ALT = liver or biliary tract disease