Liver Flashcards
What percentage of cardiac output goes to the liver?
25%
What is the largest visceral organ?
Liver
What percentage of blood flow to the liver comes from the portal vein?
67%
What percentage of blood flow to the liver comes from the hepatic artery?
33%
T/F: Clinical signs of liver disease are variable.
True
The liver of a carnivore is what percentage of its body weight?
3-4%
The liver of an omnivore is what percentage of its body weight?
2%
The liver of a herbivore is what percentage of its body weight?
1%
Portal triads are composed of what 4 components?
- Bile ducts
- Branches of portal vein
- Hepatic artery
- Nerves and lymphatics
What is the name of the extracellular matrix that forms an abrupt border with a circumferential row of hepatocytes that surrounds the portal tract is what?
Limiting Plate
Which hepatic zone surrounds the portal triads?
What is another name for it?
- Zone 1
- Centroacinar
Which hepatic zone is the intermediate or midlobular area?
What is another name for it?
- Zone 2
- Midzone
Which hepatic zone surrounds the central veins?
What is another name for it?
- Zone 3
- Periacinar
What percentage of the liver mass is composed of hepatocytes?
Approximately 80%
What are the macrophages regional to the liver called?
Kupfer cells
Which cells produce and maintain extracellular matrix and store vitamin A?
Stellate cells
What are 7 functions of the liver?
- Bilirubin metabolism
- Bile acid metabolism
- Carbohydrate metabolism
- Lipid metabolism
- Xenobiotic metabolism
- Protein synthesis
- Immune function
What percentage of liver parenchyma is injured before clinical signs appear?
Approximately 75%
What are 5 examples of liver enzymes?
- AST
- ALT
- LDH
- Alkaline phosphate
- Gamma-glutamyl transpeptidase
What are commonly used as biomarkers of liver injury?
Liver enzymes
T/F: Liver lesions are not very common.
False - they are fairly common.
Is a liver lesion usually significant enough to result in hepatic failure?
No
What can help to identify the presence and cause of liver disease?
Interpretation of the location and type of liver lesions.
What can be helpful with making a diagnosis of liver disease?
Histopathology
What are 3 examples of portals of entry of injurious agents?
- Hematogenous
- Retrograde through biliary and pancreatic ducts
- Direct extension through the liver capsule
What are 6 possible mechanisms of liver injury?
- Metabolic bioactivation of chemicals to reactive species
- Stimulation of autoimmunity
- Stimulation of apoptosis
- Disruption of calcium homeostasis
- Canalicular injury
- Mitochondrial injury
What are 5 possible responses to liver injury?
- Atrophy
- Hypertrophy and hyperplasia
- Regeneration of parenchyma
- Replacement by fibrosis
- Biliary hyperplasia
What are 4 possible causes of atrophy of the liver?
- Increased catabolism
- Decreased blood flow
- Decreased bile flow
- Pressure
T/F: The liver has considerable reserve and regenerative capacity.
True
What is liver regeneration stimulated by?
Growth factors
What percentage of the liver can regenerate within a week?
60%
What type of cells can differentiate into hepatocytes or bile duct epithelium?
Oval (stem) cells
What are 3 requisites for liver regeneration?
- Intact framework
- Good blood supply
- Patent bile ducts
What is increased within the liver with fibrosis?
Amount of connective tissue.
With fibrosis within the liver, what cells proliferate?
Ito (stellate) cells
The significance of what is dependent upon effects on normal hepatic function and type of collagen?
Fibrosis
What is a possible cause of fibrosis in the liver?
Parasitic migration
Chronic liver injury can lead to what condition?
Cirrhosis
Regeneration seen with chronic injury can lead to what 3 possible outcomes?
- Hepatocellular nodular proliferation
- Fibrosis
- Impaired blood and bile flow
What is cirrhosis characterized by?
Nodular regeneration and post-necrotic scarring.
What is seen at the end-stage of many chronic liver diseases?
Cirrhosis
T/F: With cirrhosis, the liver is usually larger in size.
False - it is usually reduced in size.
Bile duct proliferation is also known as what?
Biliary hyperplasia
What is another name for capsular hepatic fibrosis?
What species is it common in?
- Perihepatitis filamentosa
- Horses
Can capsular fibrosis in horses be an incidental lesion?
Yes
What are 2 possible causes of capsular fibrosis?
- Resolution of peritonitis
- Parasitic migration
Focal areas of pale discoloration on the liver can be caused by what?
Tension lipidosis
Tension lipidosis can be found where?
Adjacent to mesenteric attachment.
In what species can you find tension lipidosis?
Cattle and horses
Rupture can be seen with what 2 conditions?
- Trauma
- Enlarged liver
T/F: Postmortem changes occur slowly.
False - they occur rapidly.
What are 3 examples of postmortem changes that can be seen in the liver?
- Pale, irregular foci
- Greenish black discoloration near the intestine
- Emphysema
Can autolysis occur in the liver postmortem?
Yes
What postmortem change can be seen on the surface of the liver in contact with the gall bladder?
Bile imbibition
What are 3 examples of patterns of hepatocellular degeneration?
- Random
- Zonal
- Massive
What are 3 patterns of necrosis that can e seen with random liver degeneration?
- Single cell necrosis
- Multifocal necrosis
- Piecemeal necrosis
What size are multifocal liver necrosis lesions?
< 1mm to 1 cm
What are multifocal liver necrosis lesions usually caused by?
Infections: bacterial, viral, parasitic
Which type of hepatocellular degeneration has defined areas within hepatic lobules or acini that are affected?
Zonal
What are 4 examples of zonal hepatocellular degeneration?
- Centrilobular
- Midzonal
- Periportal
- Bridging
What is a common cause for the development of periacinar or centrilobular necrosis?
Hypoxia
Which type of necrosis seen with zonal degeneration is rarely seen?
Midzonal
The etiology of periportal necrosis is often what?
Toxic
Massive hepatic necrosis involves what portion of the liver?
The entire lobule or contiguous lobules.
What is one of the most common causes of massive hepatic necrosis in a pig?
What is this condition associated with?
- Hepatosis dietetica of swine
- Generation of free radicals and deficiency of Vitamin E/Selenium
Congenital cysts are an example of what type of abnormality?
Developmental
What are congenital biliary cysts due to?
Abnormal development of bile ductules.
Are congenital biliary cysts consider a significant or incidental finding?
Incidental
T/F: Cysts have a thick wall, lined by several layers of biliary epithelium.
False - they have a thin wall, lined by a single layer of biliary epithelium.
Multiple cysts located in the liver and kidney can be seen with what disease?
Congenital polycystic liver disease
What are 3 examples of breeds that are predisposed to congenital polycystic liver disease?
- Cairn terriers
- West Highland white terriers
- Persian cats
What can be a result of congenital polycystic liver disease?
Mortality due to liver or renal failure.
It is important to differentiate congenital cysts from what?
Parasitic cysts
What type of an anomaly is a displacement?
What are 2 examples of displacements?
- Developmental
- Ventral hernia, diaphragmatic hernia
What are 5 examples of circulatory disturbances?
Which one is considered to be very rare?
- Congestion
- Infarction/ischemia (very rare)
- Thrombosis
- Congenital portosystemic shunts
- Telangiectasis
What are 2 examples of what can be seen with acute congestion?
- Slight enlargement of liver.
- Prominent reticular pattern due to congestion of centrilobular areas.
What are 2 examples of what can be seen with chronic passive congestion?
- “Nutmeg appearance”
- Reticulated pattern due to zonal congestion
What are 3 things that can be seen histologically with chronic passive congestion?
- Congestion around central veins.
- Hepatocytes around portal areas are often unremarkable.
- Midzonal fatty change is occasionally seen.
What is hepatic vein thrombosis also known as?
Budd-chiari syndrome
What are 3 characteristics of hepatic vein thrombosis?
- Hepatomegaly
- Ascites
- Abdominal pain
What is hepatic vein thrombosis caused by?
Thrombosis of the hepatic vein and the adjacent inferior vena cava.
Conditions producing thrombotic tendencies or sluggish flow such as myeloproliferative disorders, infections, trauma and neoplasia can cause what?
Hepatic vein thrombosis
What do portosystemic shunts cause?
Blood within the portal venous system to bypass the liver and drain into the posterior vena cava or the azygous vein.
What 2 conditions can be seen with congenital portosystemic shunts in cases seen in dogs and cats?
- Hepatic encephalopathy
- Ascites
What does the liver look lime in an animal with a portosystemic shunt?
Why?
- Very small
- Has been deprived of primary perfusion by portal hepatotrophic factors such as insulin, glucagon and amino acids.
What 3 things can be seen histologically with portosystemic shunts?
- Very small hepatocytes.
- Portal veins in smaller triads are small or absent.
- Hepatic arterioles are often prominent and multiple.
What must congenital portosystemic shunts be distinguished from?
Acquired shunts
What are acquired shunts due to?
Chronic portal hypertension
Which kind of shunt has multiple, thin walled and tortuous blood vessels and evidence of liver disease?
Acquired shunts
The presence of focal areas in which sinusoids are dilated and filled with blood is known as what?
Telangiectasis
How does telangiectasis appear grossly?
Irregular, circumscribed, dark-red foci of cavernous ectasia of sinusoids.
Telangiectasis is common in what 2 species?
- Cattle
- Old cats
Does telangiectasis have clinical significance?
No
What are 4 examples of accumulations that can cause metabolic disturbances?
- Fat (hepatic lipidosis)
- Glycogen
- Amyloid
- Copper
What are 2 terms used to refer to a fatty liver?
- Hepatic lipidosis
- Steatosis
What are 2 causes of hepatic lipidosis?
- Excessive entry of fatty acids into the liver.
- Decreased oxidation of fatty acids within hepatocytes.
Excessive dietary intake of fat or increased mobilization of fat from adipose tissue due to increased demand can cause what?
Excessive entry of fatty acids into the liver leading to hepatic lipidosis.
A consequence of abnormal hepatocyte function that can lead to accumulation of triglycerides within hepatocytes can be what?
Decreased oxidation of fatty acids leading to hepatic lipidosis.
Increased esterification of fatty acids to triglycerides can lead to what?
Hepatic lipidosis
Decreased apoprotein synthesis and subsequent decreased production and export of lipoprotein from hepatocytes can lead to what?
Hepatic lipidosis
Impaired secretion of lipoprotein from the liver can lead to what?
Hepatic lipidosis
Enlarged, heavy, uniform light yellow or orange liver that cuts with ease and is greasy what severed is grossly characteristic of what condition?
Hepatic lipidosis
T/F: With hepatic lipidosis, the edges of the liver are jagged and the surface is rough.
False - the edges are rounded and the surface is smooth.
T/F: With hepatic lipidosis, the tissue will float in water or fixative.
True
What are some morphologic features of the cut surface and the histological appearance?
- Cut surface: normal compared to hepatic lipidosis.
- Histological appearance: marked by hepatocellular vacuolation.
What is the preferred stain to use with hepatic lipidosis?
Oil red O
Intracellular triglycerides can be stained with what?
Osmium tetroxide
What are 3 things the significance of hepatic lipidosis depends on?
- Cause
- Severity
- Duration
Can the lesions of hepatic lipidosis be reversible?
Yes in mild cases.
What are 4 things that hepatic lipidosis can lead to?
- Hepatic necrosis
- Fatty cysts
- Fat embolism
- Liver rupture with internal hemorrhage
T/F: Fatty livers are less susceptible to toxic damage and traumatic injury.
False - they are more susceptible.
What are 3 possible causes of physiological fatty liver?
- Late pregnancy
- Heavy lactation
- Simple dietary excess
The synthesis and transport of what acts as a bottleneck in the movement of lipid through hepatocytes and triglyceride accumulates?
Low-density lipoprotein
What condition can occur following excessive fat metabolism during peak lactation in cattle or twin pregnancy in ewes?
Ketosis
The added stimulus for fatty acid oxidation caused by the drain of heavy pregnancy or lactation can be related to what condition?
Ketosis
In dairy cattle, what disease usually occurs in obese animals within a few days after parturition?
Bovine fatty liver syndrome
What are 5 examples of events that can cause a cow to go off feed which can lead to bovine fatty liver syndrome?
- Retained placenta
- Metritis
- Mastitis
- Abomasal displacement
- Parturient paresis
Both increased mobilization of adipose tissue, which results in increased influx of fatty acids to the liver and decreased export of lipoprotein from the liver leads to accumulation of lipid within the liver known as what condition?
Bovine fatty liver syndrome
T/F: The causes of feline fatty liver syndrome are poorly defined.
True
Cats that are obese, anorexic and have no other disease that could cause hepatic lipidosis could have what disease syndrome?
Feline fatty liver syndrome
What are 3 conditions that could be caused by feline fatty liver syndrome?
- Icterus
- Hepatic failure
- Subsequent hepatic encephalopathy
What condition can be seen in obese ponies, especially Shetlands?
Equine hyperlipemia
What is the pathogenesis of equine hyperlipemia?
Unknown
What are 2 examples of common endocrine disorders?
- Diabetes mellitus
- Hypothyroidism
In diabetes, when can fatty liver occur?
When insulin is deficient or inactive due to lack of functioning receptors.
Increased lipolysis resulting in increased access of fatty acids, coinciding with a shortage of ATP (due to reduced glucose availability), concludes with what?
Reduction in lipoprotein synthesis.
Injury to hepatocytes which can cause decrease formation and/or export of lipoproteins by hepatocytes and decreased oxidation of fatty acids within hepatocytes can lead to what?
Accumulation of fat
Accumulation of fat within cells arising as a consequence of cellular injury is called what?
Fatty degeneration
T/F: Glycogen is normally stored in hepatocytes.
True
Excessive storage of glycogen in the liver can be seen with what 3 conditions?
- Diabetes mellitus
- Hyperadrenocorticism (steroid induced hepatopathy)
- Glycogen storage diseases
Excessive levels of endogenous or exogenous glucocorticoids can cause what?
Extensive swelling of hepatocytes owing to accumulation of glycogen.
What can induce glycogen synthetase and so enhance hepatic storage of glycogen?
Glucocorticoids
An enlarged, pale liver due to swollen hepatocytes (particularly in the midzonal areas) can be due to what?
Steroid induced hepatopathy
What is a possible differential diagnosis for steroid induced hepatopathy?
Which stain can be used to distinguish between the two conditions?
- Hepatic lipidosis/fatty change
- PAS stain
What condition usually occurs as a consequence of prolonged antigenic stimulation such as chronic infection or repeated inoculations of an antigen?
Hepatic amyloidosis
What are 3 breeds where familial predispositions to hepatic amyloidosis can be detected in?
- Abyssinian cats
- Siamese cats
- Chinese Shar-Pei dogs
Where in the liver does amyloid usually accumulate?
What does this accumulation cause?
- In the space of Disse
- Atrophy of hepatic cords
What is the name of the special stain used to detect amyloid?
Congo red
T/F: Copper is a non-essential trace element.
False - it is essential
