Liver 2 Flashcards
Name the cell type in the liver that deposits collagen in cases of hepatic fibrosis
Ito (hepatic stellate) cell
What is the role of Ito (hepatic stellate) cells in hepatic disease?
To deposit collagen (which can lead to hepatic fibrosis)
What is the alternative name for a hepatic Ito cell?
Hepatic stellate cell
What the alternative name for a hepatic stellate cell?
Ito cell
Ito (hepatic stellate) cells are responsible for collagen deposition in hepatic disease and fibrosis. What is their role in the non-diseased liver?
Storage of vitamin A and fat
Where, precisely, are hepatic Ito (stellate) cells found within the liver?
In the space of Disse
Explain why fibrosis within and around hepatic sinusoids is such a serious change.
The space of Disse becomes reduced or obliterated by collagen deposition. The ability of the liver to carry out its synthetic, catabolic and excretory roles is severely compromised by this reduced exposure of hepatocytes to plasma.
What does the term cirrhosis mean?
Diffuse hepatic fibrosis accompanied by regenerative nodule formation (end-stage liver is a better term than cirrhosis)
What is the term for diffuse hepatic fibrosis accompanied by regenerative nodule formation?
Cirrhosis (or end-stage liver)
Describe the appearance of an end-stage (cirrhotic) liver
The liver is small, firm, and irregular with nodules of regenerative parenchyma separated by tracts of fibrous connective tissue.
Name 3 causes of end-stage liver (cirrhosis). [The answer has 6 causes so if you can name even more than 3 that’s great]
- Chronic toxicity; 2. Chronic cholangitis or obstruction; 3. Chronic congestion (right-sided heart failure); 4. Inherited copper or iron storage disorders; 5. Chronic hepatitis; 6. Idiopathic
Explain why hepatotoxins commonly result in periportal, rather than centrilobular necrosis.
Hepatocytes in Zone 1 of theliver lobule (periportal; closest to portal areas) are the first to receive blood and, therefore, may be the first to be injured by circulating toxins -> PERIPORTAL NECROSIS
Which pattern of hepatic necrosis (centrilobular or periportal) is more likely in cases of hepatotoxicity and why?
Periportal. Hepatocytes in Zone 1 of theliver lobule (periportal; closest to portal areas) are the first to receive blood and, therefore, may be the first to be injured by circulating toxins -> PERIPORTAL NECROSIS
Which pattern of hepatic necrosis (centrilobular or periportal) is more likely in cases of anemia or hypoxia and why?
Centrilobular. Hepatocytes in Zone 3 of the lobule (centrilobular; closest to central veins) are the last to receive blood and, therefore, may be the first to be injured by ischemia -> CENTRILOBULAR NECROSIS
Name 3 routes in which bacteria can reach the liver via the bloodstream.
- The portal vein; 2. The umbilical veins from umbilical infections in newborn animals; 3. The hepatic artery, as part of a generalized bacteremia.
Name 3 NON-vascular routes by which bacteria may reach the liver.
- Ascending infection of the biliary system; 2. Parasitic migration; 3. Direct extension of an inflammatory process from tissues immediately adjacent to the liver, such as the reticulum.
What are the two main syndromes caused by Rhodococcus equi in foals?
Typically enterocolitis and/or bronchopneumonia
Which domestic species, and which specific subgroup in this species, is most commonly affected by disease due to Rhodococcus equi?
Horses; foals most commonly affected
You are performing a necropsy on a foal and find disseminated abscesses throughout the mesenteric lymph nodes, spleen, liver and large intestine. What is the most likely cause?
Rhodococcus equi
How is Rhodococcus equi spread among horses?
It is present in the soil and feces, and farms can be endemically infected. It may be ingested or inhaled to cause infection, but inhalation is believed to be the more common route.
You are performing a necropsy on a feedlot steer and find numerous foci of necrosis and abscess formation throughout the liver. What are the likely (a) cause and (b) pathogenesis?
(a) Fusobacterium necrophorum; (b) Damage to ruminal mucosa (rumenitis) -> bacteria enter portal circulation -> shower liver -> hepatic abscesses -> poor production
Explain why feedlot cattle with rumenitis may develop hepatic and even pulmonary abscesses.
Damage to ruminal mucosa (rumenitis) -> bacteria enter portal circulation -> shower liver -> hepatic (and possibly pulmonary) abscesses
Name the organism that causes Tyzzer’s disease.
Clostridium piliforme
Which hepatic disease is caused by Clostridium piliforme?
Tyzzer’s disease