week 11 - disorders of the liver/renal system Flashcards
What is the function of the liver?
Produces bile
Is important for metabolism
Helps remove toxins from blood
Describe the liver’s blood supply?
Blood comes in via:
Hepatic artery (carries oxygenated blood) and hepatic portal vein (carries nutrient rich blood)
Blood exits via:
Hepatic vein
What is the liver made out of?
Lobules
What are the 3 zones of a lobule?
Zone 1 - periportal
Zone 2 - midlobular
Zone 3 - perivenular
What is the function of zone 1?
It is the first zone to come into contact with blood
Deals with hepatotoxins
What is the function of zone 2?
It is regenerative and is the source for new hepatocytes
What is the function of zone 3?
What do hepatocytes do?
They perform the majority of roles in the liver
What is bile?
It breaks down fats into fatty acids
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What is AST and ALT
stands for aspartate aminotransferase and alanine aminotransferase and they are both expressed in the liver.
If you have increased levels of ASL and ALT (a ratio higher than 1) then it’s a sign you have liver damage
AST and ALT can leak into your bloodstream when your cells get damaged
What are the various tests to test your liver function?
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What are the stages of liver damage?
- Healthy liver
- Steatosis inflammation
- Fibrosis
- Cirrhosis
- Liver cancer
What is steatosis?
It is where there is a build up of fat in the hepatocytes.
The liver is a primary organ for lipid metabolism however when one has steatosis, the excess fat cannot be processed so accumulates in vesicles.
This can be seen as enlarged liver cells with many fat droplets present in the cytoplasm
What are the signs of liver disease?
Jaundice
Itching (pruritus)
Ascites
What is jaundice?
Presents as yellowish discolouration of the skin caused by hyperbilirubinaemia and the deposition of bile pigments.
Bilirubin is usually metabolised but in hyperbilirubinaemia bilirubin fails to get metabolised so patients have a high serum bilirubin level greater than 2mg/ml
Explain the theory Why do people with liver failure experience itching aka pruritis?
An elevation of serum bile salts stimulate nerve endings to produce the itching sensation.
What are other alternative explanations as to why liver disease patients experience itching?
Raised histamine levels in liver disease patients cause itching
Patients with liver disease are not able to clear toxins from the blood which may build up in the brain, leading to cognitive issues, producing an itching sensation.
Describe what ascites is in patients with liver disease
It is a build up of fluid in the abdomen.
Caused by liver dysfunction and cirrhosis which can lead to portal hypertension.
Portal hypertension (high blood pressure in portal vein) causes fluid to leak out of the veins causing ascites.
What is hepatomegaly and what is it caused by?
It is an enlarged liver caused by liver diseases such as GSD, carcinoma, hepatitis etc
What is non alcoholic fatty liver disease (NAFLD)
It is a build up of fat in the liver NOT caused by alcohol
What are some NAFLD risk factors?
Being obese
Diabetes
high BP/cholesterol
PCOS
hypothyroidism
What are some thing that can prevent NAFLD?
Lose weight
exercise
healthy diet \
how does chronic alcohol intake cause liver disease?
The liver is most exposed to alcohol as the liver is where metabolism of alcohol takes place.
This results in hepatocyte damage via oxidative stress and increases fat deposits in the liver
Over time, the structure of the liver changes due to damaged hepatocytes.
Describe stage 1 of alcohol induced liver damage?
Steatosis occurs - build up of fats in the liver
Describe stage 2 of alcohol induced liver damage?
Fibrosis occurs
Describe stage 3 of alcohol induced liver damage?
Cirrhosis occurs
What is liver cirrhosis?
It is when the scar tissue blocks blood flow of the liver - obstructs the portal blood flow causing portal hypertension.
Also results in hepatocyte damage meaning that when blood passes through the liver to get the toxins removed, there is a reduced amount in removed toxins from the blood.
What is portal hypertension/
high blood pressure in the portal vein caused by cirrhosis which causes back pressure in the portal vein.
It can lead to varicose veins, ascites as back pressure forces fluid out and formation of collaterals which are thin walled vessels that can rupture.
Symptoms of portal hypertension?
Enlarged gut due to ascites
Blood in vomit/stool bc of weak collateral vessels
Tiredness, pallor, breathlessness due to bleeding
Diarrhoea and poor weight gain due to swelling of blood vessels in intestine lining which reduces absorption of digested food.
What are the causes of portal hypertension?
Post hepatic causes - thrombosis of the portal vein
Intra hepatic causes - cirrhosis
Post hepatic causes -b obstruction between the liver and right heart.
What other issues can liver dysfunction cause?
Hepatorenal syndrome
Hepatopulmonary syndrome
Hepatic encephalopathy
What is hepatorenal syndrome and what is ti caused by?
It is the rapid deterioration off the kidneys due to liver failure.
Caused by dilation of the gut which constricts renal circulation.
Results in low blood volume to the kidneys
What is hepatopulmonary syndrome and what is it caused by?
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What is hepatic encephalopathy and what is it caused by?
Normally, the liver removes toxic substances from the blood but a person with liver dysfunction can’t do that properly so therefore, the toxic substances accumulate in the blood which damages brain cell function.
Symptoms include impaired cognition, reduced consciousness etc
What are the stages of hepatic encephalopathy?
stage 1 - mild confusion, irritable, reduced attention, sleep disturbances
stage 2 - disorientation, inappropriate behaviour, drowsy
stage 3 - confusion, aggressive,
stage 4 - coma
Give a brief function of the kidneys, ureters, bladder and urethra
kidneys - filter blood
ureters - transports urine to bladder
bladder - stores urine
urethra - discharges urine from the body
What else does the kidney do other than filter blood?
regulation of blood ion composition, blood pH, blood volume
maintains blood osmolarity
release renin to reg blood pressure
excretion of waste products
what are the 3 structures of the kidney?
renal cortex - filters the blood
renal medulla - regulates water, salts
renal pelvis - collects urine and sends the urine to the bladder
What is the function of the nephron
glomerular filtration
tubular secretion/reabsorption
What is the glomerulus?
start of the nephron
it is a network of capillaries which filters in water, glucose, amino acids, urea ions into the tubule but does not let in large proteins, red/white blood cells, platelets.
The glomerulus contains podocytes which regulate selective filtration of the blood
Describe the function of podocytes?
highly specialised cells that regulate selective filtration of the blood
they wrap around capillaries,
they have slits in them so blood can be filtered through
What is the Bowmans capsule?
structure that surrounds the glomerulus
It collects the content filtered out of the plasma then sends it into the PCT
