Liver Flashcards
What vessels leave/ enter the liver
Portal vein= brings food rich blood from the gut
Hepatic artery= brings arterial blood
Hepatic veins= taking away processed blood into the vena cava
Lymphatics taking away some lymph
Hepatic ducts removing bile to the gallbladder and hut
What is the blood supply to the liver?
Hepatic artery 25% (fully oxygenated blood)
Portal vein 75% (full of rich nutrients and toxins brought from the gut)
What is the layout of the liver?
Cells are arranged in perforated plates, one cell wide. Between the plates are sinusoidal blood channels, lined by endothelial cells
What are liver lobules?
Hexagonal areas of the liver
Along the central axis of each lobule runs a central vein, which is a branch of the hepatic vein
What is found in the portal triad?
Portal vein, bile duct and hepatic artery
What happens to the blood collected in the central veins?
Goes to sublobar veins, then collecting veins, then hepatic veins leaving the liver
What is a liver acinus?
The liver acinus represents a functional unit comprising of 3 or so lobules
The territory of an acinus has, as its axis, one final branch of the portal vein and is subdivided into 1. periportal- deals with sampling blood components and accordingly changes composition , 2. intermediate and 3. perivenous where blood gets enriched
Zone 1 gives signals to zone 3 where e.g. glycogen is broken down and low blood sugar is solved
In what direction is hepatic lobular blood flow and intralobular bile flow?
Hepatic blood flow= from branches of portal vein and hepatic artery on the periphery to the central veins via the sinusoids
Bile flow= lobules centre towards peripheral bile ducts in the bile canaliculi
What are liver sinusoids?
Low pressure vascular channels that recieve blood from portal vein/hepatic artery and deliver it to the central veins
What are sinusoids lined by and is on the other side of them?
Fenestrated endothelial cells, which are loosely attached.
Plasma can thus pass through into the perisinusoidal space of disse, where they can interact with hepatocytes
What are Kupffer cells and where do they lie?
a phagocytic cell which forms the lining of the sinusoids of the liver and is involved in the breakdown of red blood cells.
What are stellate cells?
Hepatic stellate cells reside in the perisinusoidal space, between sinusoidal endothelial cells and hepatocytes, store vitamin A, and produce collagen when activated (cirrosis)
What are the different cells shown on this image of a sinusoid?
How are the hepatocytes arranged in the liver?
80% of mass of liver is hepatocytes, arranged in plates that anastomose with one another. Cells are polygonal in shape and can have two nuceli
Sides can be in contact with sinusoids or neighbouring hepatocytes (lateral faces)
A portion of the lateral faces are modified to form bile canaliculi
What occurs in liver cirrhosis?
Kupffer cells get activated and the sellate cells also get activated and produce collagen
Fenestrations start to close up due to collagen deposition
Sinusoidal pressure thus increases- portal hypertension
Many hepatocytes die and others get surrounded by fibrous tissue
Lose the hexagonal lobe structure and portal triads bridge
Where does bile flow within the liver?
Bile is collected in the bile canaliculi between hepatic cells which lead to canals of Hering which drain into bile ducts in the portal triads
How is lymph formed in the liver?
Lymph is formed by filtration of the plasma into the spaces of Disse as blood flows through the sinusoids
Filters through space of disse then lymph tracts are formed although the microanatomy is not clear
What are the following labels?
What are the following missing labels?
What are the two main functions of the liver in terms of metabolism?
Glucose metabolism
Bilirubin metabolism
How is glucose regulated in the liver?
Insulin from pancreas stimulates formation of glycogen in the liver
Glucagon from pancreas stimulates release of glycogen in the liver
How is bilirubin metabolism regulated in the liver?
Haemoglobin in the blood is ultimately broken down to bilirubin
If there is high levels will be turned to unconjugated the liver will turn it to conjugated and it will either go into the billary system to the small intestine and faeces or excreted in the urine
How does the liver deal with toxins?
Toxins gathered through skin, breathing or food
Through help of co-enzymes it turns them into water soluable waste products which are put into the bile into the stoo l or excreted in the urine
What causes and are the symptoms of jaundice?
Yellowing of skin and eyes is associated with accumulation of bilirubin in the skin, mainly caused by liver and gallbladder disorders
Causes- gallstones, tumours, cirrosis due to e.g. alcohol
What are some routine liver function tests?
Bilirubin
ALT and AST
GGT
Alkaline phosphatase
Albumin
Prothrombin time ratio
What does prothrombin time and albumin reflect?
Ability of blood to clot- clotting factors produced by liver
Synthetic function of liver
Same for albumin- synthesised in albumin
How often are red blood cells broken down via haemolysis?
Every 3 months
What does failure to clear gut derived toxins result in?
Failure to clear gut derived toxins from the liver such as NH3 results in an overwhelming number of toxins circulating in the blood which can cause encephalopathy
Symptoms include drowsiness and confusion
Why in liver failure can clotting factors and anticoagulants be balanced?
The liver produces both clotting factors and anticoagulants so it may stop producing both and they will still be in balance with one another
What is the half life of clotting factors and albumin?
Clotting factors= 6-12 hours
Albumin= weeks
What is the difference between chronic and acute liver failure?
Time scale; acute is <2-3 months and chronic is >2-3 months
Usually have different aetiologies and different clinical presentations
What signs are there in acute liver disease?
High ALT
Uncommon- with jaundice and coagulopathy
Rare- with jaundice/coagulopathy and encephalopathy
What is the most common cause of acute liver injury?
Paracetemol overdose- 80-90% of cases
What are causes of acute liver failure?
Drugs
Acute viral infections (Hep B,A,E)
Autoimmune hepatitis
Seronegative (non A-E) hepatitis
Vascular diseases
Metabolic diseases such as Wilson’s
Cancer
Ischaemia due to hypotension
Toxins- amanita phalloides mushroom and carbon tetrachoride
What drugs can cause acute liver failure?
Antibiotics especially anti-TB meds
Antiepileptics
Herbal remedies
Ecstasy
Paracetemol
What is Wilson’s disease?
Accumulation of copper, causes acute liver failure. Commonly seen in teens and young adults
What is stigmata of cirrhosis?
Clinical features of chronic liver disease
Include spider naevi, palmar erythema, jaundice, hair loss, leuconychia, asterixis, ascites
What is the antidote to paracetemol overdose?
N-acetyl cysteine infusion
How do you treat coagulopathy in acute liver failure?
Give Vit K - it is a substrate that is required for certain clotting factor synthesis (II, VII, IX, X)
If this does not work, give fresh frozen plasma which contains clotting factors, however you cannot measure liver function through clotting tests
What signs indicate a patient will not recover spontaneously in a paracetemol overdose?
Pro-thrombin time > 100
AND anuric or creatinine > 300
AND Grade 3-4 encephalopathy (coma)
What does malaise mean?
Feeling ‘out of sorts’
What does a ALT falling in acute liver disease show?
Injury is getting better
OR running out of hepatocytes to die
What signs indicate a patient will not recover spontaneously in non-paracetemol acute liver failure?
3 out of 5= unlikely to recover spontaneously
- age < 10 or > 40
- aetiology (drug or seronegative cause worse than viral)
- prothrombin time > 50
- bilirubin > 300
- Time from jaundice to encephalopathy < 7 days
What is the management for acute liver failure?
Identify and treat the underlying cause (NAC for paracetemol, antivirals for Hep and steroids for autoimmune hepatitis)
Supportive care, monitoring and liver transplant if needed
Why can hepatic encephalopathy occur in chronic liver failure?
- Failure of hepatocyte function (NH3 clearance)
- Portosystemic shunting where new veins arise and blood from portal system bypasses liver into the systemic circulation e.g. eosphageal varices
What can trigger hepatic encephalopathy?
Constipation
Drugs such as opiates and sedatives
Dehydration
Infections
GI bleeding
What is ascites and what can it result in?
A condition in which fluid collects in spaces within the abdomen
Causes low albumin, portal hypertension and renal hypoperfusion
What are the most common causes of chronic liver disease?
ANY CAUSE OF CIRRHOSIS
- Alcohol
- NAFLD
- Hepatitis B or C
- Haemochromatosis
- Wilsons disease
- Primary biliary cholangitis
- Autoimmune hepatitis
What is Haemochromatosis?
Haemochromatosis is an inherited condition where iron levels in the body slowly build up over many years.
What is cholangitis?
Cholangitis is an inflammation of the bile duct system
What is spider naevi?
Sign of chronic liver failure, a cluster of minature red blood vessels under the skin
What is important to do when you suspect alcohol related cirrhosis?
Exclude other conditions including:
hepatitis B/C
haemochromatosis autoimmune liver disease
What is the management for chronic liver failure?
Identify and treat underlying cause
Abstinence for alcohol
Antivirals for hepatitis B/C
Steroids for autoimmune hepatitis
No treatment for jaundice
Low salt diet and diuretics for ascites
Laxatives and antbiotics for encephalopathy
Liver transplantation if appropriate
What is given in alcohol withdrawal patients?
Diazepam
Vit B supplements (Pabrinex/thiamine)
What are ascites treated with?
Low salt diet and diuretics
What are varices (expanded blood vessels in the esophagus to stomach) treated with?
Beta-blocker to reduce pressure / risk of bleeding
What are the clinical symptoms of hepatitis?
Jaundice
Dark urine
Clay-coloured stool
Nausea and vomiting
Loss of appetite
Fever
Abdominal pain
Weakness
What is hepatitis?
Hepatitis is an inflammation of the liver that is caused by a variety of infectious viruses and noninfectious agents
What tests can be done to check for viral causes of hepatitis?
Enzyme immunosorbent assays
Viral antigen tests
Anti-viral antibody tests
PCR for viral load
Biopsy- not first line test
What hepatitis viruses can be transmitted parentally or sexually?
Hepatitis B,C,D
What is parental transmission?
Through blood or blood products
What hepatitis viruses are transmitted fecal-orally through food or water?
Hepatitis A and E
What hepatitis viruses are eneveloped?
Hepatitis B,C,D
Who can hepatitis D infect?
Only can infect someone who is hepatitis B positive
What hepatitis virus infections can become chronic?
B,C,D
What is the incubation time of hep A, and who does it affect?
Incubation time is 10-50 days then there is an abrupt onset of symptoms commonly with pyrexia (fever), can be asymptomatic
Primarily seen in children and young adults
How is hepatitis A treated?
Treatment= supportive
Resolves spontaneously followed by life long immunity
How is hepatitis A diagnosed?
Specific diagnosis is made by the detection of (IgM) antibodies in the blood.
IgG antibodies are also present and RNA is in the blood, both can be tested forf
What is the incubation time for hep B virus and who is it seen in?
40-180 days
Primarily seen in babies and young adult
How can hep B be transmitted?
Parentally, sexually and vertically (mother to baby in pregnancy)
What is the treatment for hep B infection?
For chronic infection
Interferon alpha OR antivirals (eg, tenofovir, entecavir)
There is also a surface antigen vaccine available for prevention
What are the different hep B antigens (and antibodies) that can be tested for?
Hep B surface antigen (HBsAg) found in acute and chronic
Hep B core antigen (HBcAg) found in recent infection
Hep B E antigen (HBeAg) found in active
Anti-HBcAg IgG and IgM can be found- recent or past infection
In what areas of the world are chronic hep B carriers most high?
South-East Asia, parts of China, sub-saharan Africa
How is Hep C usually diagnosed in patients?
The acute phase is often completely asymptomatic, patients usually picked up randomly on screens when they are in the chronic stage
Is there a vaccine for Hep C?
NO
What is the treatment for Hep C chronic infection?
Antivirals such as protease inhibitors
What is chronic infection of hep B and C associated with?
Hepatocellular cancer
What are the different tests that can be done to test for hep C?
Anti Hep C antibodies- recent or past infection
Hep C antigens- active infection
PCR- determines viral load