Hepatobilliary Flashcards
What is the largest parenchymal organ?
The liver
It is separated into two lobes (left and right lobes) by the falciform ligament.
What artery delivers oxygenated blood to the kidneys?
The hepatic artery
How does the liver metabolize, process, and detoxify nutrients?
Nutrients are absorbed in the small intestine, and the blood from the GI goes to the liver via the hepatic portal vein. This allows the blood to interact with liver lobules. The lobules contain all of the chemical and enzyme machinery to break down nutrients
Describe the anatomy of liver lobules?
They are hexagonal functional subunits of the liver. At each vertex of the hexagonal unit, contains three vessels. The first vessel is the portal vein (brings blood from GI), bile duct (contains digestive substances), hepatic artery (actually supplies hepatic tissue)
What is a common response to liver damage?
Fibrosis can develop, causing liver function to decrease
What are some functions of the liver?
Metabolism
Production of bile
Cholesterol metabolism
Glucose storage and release
Iron storage
Production of clotting factors, serum proteins, fat-soluble vitamins, and proteins reacting to infections
What are some strategies employed by the liver to clear drugs from the system?
Converts drug to inactive form
Prodrug to active form
Increased solubility or lipohillicity
The exact pathway depends on chemical structure
What is the function of bile?
Its function is to aid in the digestion of fats in the duodenum.
Bile is composed of bile acids and salts, phospholipids, cholesterol, pigments, water, and electrolytes
How much bile does the liver excrete in a day?
500-1000mL
What is the process of normal bilirubin metabolism?
- Hemoglobin release and breakdown (spleen, bone marrow)
- Heme enzymatically converted to bilirubin
- Bilirubin enters the liver through the circulation (unconjugated)
- Hepatocytes add additional functional groups to bilirubin to increase its solubility and excretion
- Most of the conjugated bilirubin then is excreted in the bile
- Bile enters the GI tract
- A small fraction of the bilirubin is reabsorbed and sent back to the liver
- Most of the bilirubin (90% is excreted in the faeces after being enzymatically reduced by colon bacteria)
- The breakdown products contribute to faecal colour
What are some genetic conditions associated with the liver?
Storage disorders and hyperlipidemia
What are some infections associated with the liver?
Hepatitis (A, B, C, D/E, Epstein-Barr, herpesviruses, adenovirus)
What are some acquired liver diseases?
The following two are responsible for the bulk of liver diseases in Canada:
Alcohol liver disease
Non-alcoholic fatty liver disease (NAFLD)
Other acquired liver diseases:
Liver involvement in systemic disease (TB, storage diseases)
Cholestatic syndromes (bile duct clotting)
Drug-induced liver injury
Vascular injury/disease
Mass lesions (tumour, abscess, cyst)
How many people in Canada have liver disease?
1 in 10 have liver disease (3M Canadians)
95% of deaths from chronic liver disease are due to:
Chronic hepatitis B or C
Alcoholic liver disease
Non-alcoholic fatty liver disease (NAFLD)
Liver cancer
What are some risk factors for liver disease?
Obesity/Diabetes (metabolic syndrome)
Exposure to certain chemicals or toxins including drugs, herbals, illegal drugs (ex. Acetaminophen overdose)
Alcohol abuse
Family history of liver disease
Hepatitis B or C
Is liver disease apparent in its early stages?
It can be asymptomatic
What are some symptoms associated with advanced liver disease?
Jaundice (yellowing of the skin and eyes due to elevated bilirubin in the blood)
Nausea (vomiting or loss of appetite)
Abdominal swelling (ascites) or tenderness in the area of the liver
Chronic fatigue
Itchy skin (pruritis)
Dark coloured urine
Pale stool
Dementia-like confusion
What is jaundice and why does it matter?
An elevation of serum bilirubin that gives a yellowish colour to skin, nails, and sclera
Jaundice indicates a problem with the liver’s processing of bile (could involve liver injury or liver disease, or more bilirubin is present)
What are the three types of jaundice?
Prehepatic
Hepatic
Posthepatic
What is the issue in prehepatic jaundice?
There is nothing wrong with liver or billiary function, just too many RBCs
(ex. Could be fetal jaundice)
What is the issue in hepatic jaundice?
It is an intrinsic issue with the liver. The liver is unable to transform unconjugated bilirubin into its conjugated form
What is the issue in posthepatic jaundice?
An obstruction (gallstone) of the bile duct causes bile to backup. This means that the liver is no longer able to process bilirubin, causing it to buildup in the blood
When the liver is damaged, does it retain the ability to regenerate a smooth organ surface?
No, it is lumpy
What is non-alcoholic fatty liver disease (NAFLD)?
Associated with obesity, Type 2 diabetes, hypertension, dyslipidemia, excess caloric intake with macronutrient imbalance
Can be silent or have perceptible symptoms (abdominal pain, fatigue, jaundice at more advanced stages)
It is reversible with weight loss and exercise, and dietary changes (cut out excess carbs, fast food, red meat)
What are some disorders that cause hepatic jaundice?
Viral hepatitis (A, B, C)
Drug-induced liver disease
Chronic hepatitis due to various causes
Cirrhosis (liver becomes fibrotic after some severe chronic injury)
Liver metastasis of cancer
Treatment of the underlying condition and avoidance of alcohol and hepatotoxic drugs is important
What are some disorders that cause post-hepatic jaundice?
Inflammation, scarring, gallstones block outflow of bile
Pancreatic or biliary disorders involving inflammation and obstruction
(RARE) Carcinoma
What is cholestasis?
Cholestasis can be due to functional impairment of the hepatocytes in the secretion of bile and/or due to an obstruction at any level of the excretory pathway of bile
What is the difference between intrahepatic and extrahepatic cholestasis?
Intrahepatic cholestasis: impairment of bile formation
Extrahepatic cholestasis: Impedance to bile flow occurs after it is formed