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15 Cards in this Set
- Front
- Back
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Give the simplified 4 step version of cholesterol synthesis (in the endoplasmic reticulum)
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Acetate
Mevalonate Activated Isoprene Squalene Cholesterol |
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What is the major regulated step of cholesterol biosynthesis and what effects it?
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The conversion of HMG-CoA to Mevalonate by the enzyme HMG-CoA reductase.
Cholesterol, bile acids and statins inhibit this enzyme so less cholesterol is produced (cholesterol involved in positive feedback) |
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How does liver disease cause malabsorption and diarrhoea?
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A function of the liver is to produce bile salts which help emulsify dietry fat. If fat is not emulsified into its digestible form to pass through gut epithelia then no fat soluble vitamins can be absorbed causing malabsorption
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What are the two primary bile acids?
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Cholic acid
Chenodeoxycholic acid |
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What are the two secondary bile acids?
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Deoxycholic acid
Lithocholic acid |
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Give the three main steps in bile production.
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1. Hepatocytes secrete bile into canaliculi
2. Cholangiocytes add a watery HCO3- (bicarbonate) fluid into it 3. Hepatic bile is diverted to gall bladder where it is stored and isotonically salt and water is removed |
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Where is bile secreted
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Bile reaches the second part of the duodenum through the Ampulla of Vata and is a mixture of dilute hepatic bile and concentrated gall bladder bile
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What are biles two main functions?
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1. Provides excretory route for solutes not excreted by the kidney (bilirubin, cholesterol, fatty acids, albumin)
2. Bile acids vital for lipid absorption through their micelle-forming properties |
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What is a micelle
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A micelle is an aggregate of surfactant molecules dispersed in a liquid colloid. Hydrophobic lipid tails face inwards and polar head groups face outwards.
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What clinical features do disturbances of biotransformation of gonadal hormones cause?
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Gynaecomastia
Testicular atrophy Spider naevi |
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Why do people with liver disease sometimes get a flapping tremor?
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Liver funtion - detoxificaiton of nitrogenous waste.
When these waste toxins can not be biotrnasformed then they can cause hepatic encephalopathy (brain poisoning by toxic substances in the blood) causing a tremor. |
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How does liver disease lead to oedema?
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Liver function - remove excess aldosterone from the blood.
Excess aldosterone causes sodium retention in the kidneys which causes water retention by the osmotic pressure causing oedema Also, less albumin is being produced so water is retained due to increased oncotic pressure |
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What may be strange about the blood of a patient with liver disease?
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The liver synthesises coagulation factors so a diseased liver would produce less. Patients have an increased tendency of bleeding and a HIGH INR (international normalised ratio)
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What is haemochromatosis?
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Iron overload, treated with venesection (taking blood).
Causes cirrhosis via Fe2+ toxicity. |
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How does the liver act as a protective barrier?
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Kupffer cells (specialised macrophages) line the sinusoids and the liver filters portal blood to remove bacteria and toxins.
Damage to this barrier leads to higher risk of bacterial infection and sepsis. |
