Liver Flashcards
What is a lobule?
Functional unit of the liver
What is the size/shape of a lobule?
1-2mm diameter hexagon shape
What does the lobule consist of? (6)
- Liver cells (hepatocytes)
- Central hepatic vein
- Sinusoids
- Kupffer cells
- Bile canaliculi
- Portal triads
Describe a hepatocyte
Organized in 2 layered columns converging toward a central vein in a radial pattern
What is the hepatocyte in contact with? What does it do?
Sinusoid blood- liberates substances in the blood
What does a sinusoid do?
Blood enters at the periphery of the lobule and travels to the central vein via sinusoid
Where is the sinusoid located?
B/w the hepatocytes columns
What type of blood does the sinusoid consist of? Of this blood what % does each contain?
80% Portal venous blood
20% Hepatic blood
Where are kupffer cells located?
Scattered along columns of the hepatic cells
What part of the system is the kupffer cells included in?
Reticuloendothelial system
What is the function of the kupffer cells?
Ingest and destroy foreign material (WBCs, RBCs and bacteria) and cleanse the blood
Where are the bile canaliculi located?
B/w 2 layers of the liver column cells
Are the bile canaliculi the smallest part of the biliary tree?
Yes
What divides the bile and sinusoid blood?
1 row of hepatocytes
Describe the flow of bile
Biles freed from the hepatocytes to the canaliculi- flowing towards larger bile ducts at the outer edge of the liver lobule
Converge to form larger ducts which unite to form the right and left hepatic ducts
Right and left hepatic ducts join at the porta hepatis to form the CHD
Cystic duct joins the CHD to form the CBD and drains into duo
What does the portal triad consist of?
CBD, PV and HA
Where are the portal triads located?
At the outer edge of the lobule
How many portal triads serve a single lobule?
Several
How does blood travel towards the central vein?
Blood enters periphery of the lobule via sinusoids
What state should the blood be in when in the central vein?
Clean of toxins and rich in liver secretions
What veins does the central hepatic vein converge with?
Converges into larger veins and unites into the hepatic veins and drains into IVC
Liver is the primary center for what function?
Metabolism
How many activities does the liver preform?
500 different activities
How are the functions carried out?
Hepatocytes, Kupffer cells and bile cells
What % of the liver tissue makes up hepatocytes?
80%
What is bile made of? (6)
- Bile salts
- Cholesterol
- Conjugated of steroid hormones
- Pressor amines
- Water
- Bilirubin
What is bilirubin?
Product breakdown of hemoglobin
What cells aid in the production of bilirubin? (Breakdown of RBCs)
kupffer cells and other RE cells
What forms bile salts?
Cholesterol in hepatic cells
What is the function of bile?
Emulsifies fats and aids in the production of fatty acids in the GI tract
How much bile is produced in a day?
700-1200ml/day
Where is bile stored?
GB
What is unconjugated bilirubin?
Fat soluble and not excreted by urine
Toxic to tissues
What is conjugated bilirubin? What structure secretes it?
Non-toxic and water soluble
Secreted from liver into bile canaliculi
What’s the function of the reticuloendothelial? (4)
- Produces blood cells in embryo
- Produces plasma proteins and antibodies
- Removes foreign materials and worn out RBCs
- Recovers bile pigment
What are the antibodies and plasma proteins that the reticuloendothelial produces? (3)
- Globulins- natural and acquired antibodies
- Albumin- prevents plasma loss from capillaries
- Fibrogen- aids in blood clotting
How does liver function affect the metabolism of carbohydrates?
Maintains normal glucose levels through 3 different processes
(Glycogenesis, glycogenolysis, gluconeogenesis)
The liver is a glucose buffer
How does liver function affect the metabolism of fats?
Conversion of fatty acids to phospholipids
Formation of lipoproteins and cholesterol
Proteins and carbs are converted to fat
How does liver function affect the metabolism of proteins?
Amino acid synthesis (deamiantion of amino acids)
Urea formation (removes ammonia)
Formation of plasma proteins
What products are stored in the liver?
Vitamin A, D and B12
Glycogen, fats and amino acids
Ferritin
Copper and Iron (poisons)
What is the capacity of blood the liver can store?
200-400ml
Why does the liver produce heat?
As a result of chemical reactions
What does the liver detoxify?
Converts alcohol, drugs, steroid hormones, foreign molecules to less toxic forms so they are easily removed by the system
Nitrogenous wastes from amino acids are converted to urea
How much of the body’s lymph is produced from the liver?
1/3 -1/2
What is an enzyme?
Proteins that catalyze chemical reactions
Accelerate and control Rx tests - not destroyed
Different cells in the body produce different enzymes-> tissue cell damage will release those certain enzymes in the blood stream
Reflect function in body
Can be detected through serum or urine
What is Alanine aminotransferase - ALT or SGPT?
Enzyme produced by hepatocyte
What enzyme is a specific indicator for hepatocellular damage?
ALT
ALT and AST are used in conjunction to distinguish between what 2 damages?
Cardiac and hepatic damage
Increased values of ALTs are seen in pts with what potential dx? (4)
- Hepatitis
- Cirrhosis
- Tumours
- Hepatotoxicity
What pathologies have higher valves of ALT? (2)
- Acute hepatitis
2. Nonmalignant hepatic obstruction
What is aspartate aminotransferase - AST or SGOT?
Enzyme found in the liver, muscles and tissues found in high metabolic rates
When is AST released?
When there is injury to cells in tissues
Increased valves of AST indicate are found in what pathologies? (4)
- Hepatitis
- Severe hepatotoxicity
- Cirrhosis
- MI
What pathologies release higher values of AST? (2)
- Cirrhosis
2. Metastatic carcinoma of the liver
What is alkaline phosphatase - ALP or Alk Phos?
Enzyme found in the liver, bone, intestines and placenta
When is ALP found in the bloodstream?
When liver cells are destroyed
When conditions may cause increased valves of ALP in the blood?
- Advanced pregnancy
- Bone dx
- BILIARY OBSTRUCTION
- Cancer
What is indicated when ALP is increased with a normal ALT and AST?
Diseases of the bile duct
What is lactate dehydrogenase - LDH?
Enzyme found in multiple organ systems
What is LDH used to detect?
MI or pulmonary infarcts
When does LDH increase mildly?
Hepatitis
Cirrhosis
Obstructive jaundice
When does LDH increase moderately?
Infectious mononucleosis
What is gamma glutamyl transpeptidase - GGT?
Non-specific indicator of hepatic disease
What does GGT allow amino acids to do?
Allows amino acid and peptide across the cell membrane
When does GGT increase?
Liver disease, alcoholism and post hepatic obstruction
Which enzyme is the most sensitive to the effects of alcohol in the liver?
GGT
What is alpha-feta protein - AFP?
Globulin formed in the yolk sac and fetal liver
What protein is used to monitor chemotherapy treatment?
AFP
When does AFP levels increase?
In hepatocellular carcinoma and testicular (germ cell) carcinoma
What is the most predominant pigment in bile?
Bilirubin
When are conjugated bilirubin levels elevated?
Elevated in extrahepatic bile duct obstruction
When is unconjugated bilirubin levels elevated?
In hepatocellular dx and hemolytic anemia as hepatocytes cannot conjugate bilirubin
What does “total” bilirubin consist of?
Conjugated and unconjugated
When does the total bilirubin increase?
Hepatocellular dx
What is prothrombin time (PT)?
An enzyme produced in the liver and a clotting factor is affected by levels of vitamin K
What measures the ability of blood to clot?
PT
What enzyme is prolonged in nonfunctioning or scarred liver and lack of vit K?
PT
Is PT prolonged with anticoagulant therapy?
Yes
What is INR and when is it used?
Ratio put in place of the PT
How is the INR determined?
By dividing the PT by a controlled standard
What is considered a normal INR?
Valve of 1
What INR is considered dangerous for a biopsy to occur?
> 1.2
What is activated partial prothrombin time - PTT?
Measures the clotting time of blood
Prolonged in hepatic dx and anticoagulant therapy
What is serum protein?
Albumin is a protein synthesized by the liver and maintains osmotic pressure in the blood
When are decreased levels of a serum protein seen?
Decrease levels seen in liver dysfunction
Are gamma globulins increased or decreased with liver dx?
Increased
What is a hepatitis test used to determine?
If a pt has been exposed to, is currently infected with or a carrier of viral hepatitis
