Liver Flashcards by Amber Newbigging

What is a lobule?

Functional unit of the liver

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What is the size/shape of a lobule?

1-2mm diameter hexagon shape

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What does the lobule consist of? (6)

Liver cells (hepatocytes)
Central hepatic vein
Sinusoids
Kupffer cells
Bile canaliculi
Portal triads

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Describe a hepatocyte

Organized in 2 layered columns converging toward a central vein in a radial pattern

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What is the hepatocyte in contact with? What does it do?

Sinusoid blood- liberates substances in the blood

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What does a sinusoid do?

Blood enters at the periphery of the lobule and travels to the central vein via sinusoid

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Where is the sinusoid located?

B/w the hepatocytes columns

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What type of blood does the sinusoid consist of? Of this blood what % does each contain?

80% Portal venous blood

20% Hepatic blood

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Where are kupffer cells located?

Scattered along columns of the hepatic cells

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What part of the system is the kupffer cells included in?

Reticuloendothelial system

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What is the function of the kupffer cells?

Ingest and destroy foreign material (WBCs, RBCs and bacteria) and cleanse the blood

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Where are the bile canaliculi located?

B/w 2 layers of the liver column cells

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Are the bile canaliculi the smallest part of the biliary tree?

Yes

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What divides the bile and sinusoid blood?

1 row of hepatocytes

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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

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What does the portal triad consist of?

CBD, PV and HA

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Where are the portal triads located?

At the outer edge of the lobule

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How many portal triads serve a single lobule?

Several

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How does blood travel towards the central vein?

Blood enters periphery of the lobule via sinusoids

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What state should the blood be in when in the central vein?

Clean of toxins and rich in liver secretions

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What veins does the central hepatic vein converge with?

Converges into larger veins and unites into the hepatic veins and drains into IVC

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Liver is the primary center for what function?

Metabolism

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How many activities does the liver preform?

500 different activities

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How are the functions carried out?

Hepatocytes, Kupffer cells and bile cells

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What % of the liver tissue makes up hepatocytes?

80%

What is bile made of? (6)

1. Bile salts 2. Cholesterol 3. Conjugated of steroid hormones 4. Pressor amines 5. Water 6. 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?

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)

1. Produces blood cells in embryo 2. Produces plasma proteins and antibodies 3. Removes foreign materials and worn out RBCs 4. Recovers bile pigment

What are the antibodies and plasma proteins that the reticuloendothelial produces? (3)

1. Globulins- natural and acquired antibodies 2. Albumin- prevents plasma loss from capillaries 3. 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)

1. Hepatitis 2. Cirrhosis 3. Tumours 4. Hepatotoxicity

What pathologies have higher valves of ALT? (2)

1. 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)

1. Hepatitis 2. Severe hepatotoxicity 3. Cirrhosis 4. MI

What pathologies release higher values of AST? (2)

1. 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?

1. Advanced pregnancy 2. Bone dx 3. BILIARY OBSTRUCTION 4. 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?

What enzyme is prolonged in nonfunctioning or scarred liver and lack of vit K?

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