Liver Biosynthetic Function
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Liver Biosynthetic Function

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Questions and Answers

Which function is primarily responsible for the storage of glucose in the liver?

  • Gluconeogenesis
  • Glycogenesis (correct)
  • Lipogenesis
  • Glycogenolysis

    • What is the role of insulin concerning glucose and glycogen in the liver?

  • It promotes glycogen breakdown.
  • It increases blood glucose levels.
  • It stimulates gluconeogenesis.
  • It facilitates glycogen storage. (correct)

    • Which type of metabolism involves the conversion of fatty acids to ketone bodies in the liver?

  • Lipid Metabolism (correct)
  • Carbohydrate Metabolism
  • Nucleic Acid Metabolism
  • Protein Metabolism

    • What compound is synthesized by the liver that plays a crucial role in the removal of ammonia from the body?

    <p>Urea</p> Signup and view all the answers

    Which of these statements is true regarding the liver's blood supply?

    <p>The liver has two main blood supplies that serve distinct functions.</p> Signup and view all the answers

    What happens during gluconeogenesis in the liver?

    <p>Glucose is synthesized from non-carbohydrate sources.</p> Signup and view all the answers

    With what metabolic process is the urea cycle associated in the liver?

    <p>Protein deamination</p> Signup and view all the answers

    What is the significance of the liver's ability to regenerate?

    <p>It allows the liver to maintain essential functions even after damage.</p> Signup and view all the answers

    What is the primary mechanism affected in conditions leading to microcytic anemia?

    <p>Inhibition of ALA dehydratase and ferrochelatase</p> Signup and view all the answers

    Which of the following symptoms is NOT commonly associated with porphyrias?

    <p>Increased appetite</p> Signup and view all the answers

    What triggers attacks in Acute Intermittent Porphyria (AIP)?

    <p>Drugs inducing cytochrome P450 enzymes</p> Signup and view all the answers

    How is Porphyria Cutanea Tarda (PCT) primarily diagnosed?

    <p>Analyzing urinary uroporphyrin levels</p> Signup and view all the answers

    The accumulation of which compound is primarily responsible for the neurotoxicity seen in conditions affecting hem synthesis?

    <p>ALA (aminolevulinic acid)</p> Signup and view all the answers

    What is the therapeutic approach for managing the symptoms of porphyrias?

    <p>Chelation therapy and removal of triggers</p> Signup and view all the answers

    What is a common characteristic of porphyrins in the context of porphyria disorders?

    <p>They accumulate and are excreted in urine</p> Signup and view all the answers

    Which enzyme deficiency is associated with Acute Intermittent Porphyria?

    <p>Porphobilinogen deaminase</p> Signup and view all the answers

    What is the primary function of plasma proteins in the blood?

    <p>Facilitation of blood clotting and regulation of fluid balance</p> Signup and view all the answers

    Which factor most significantly regulates the synthesis of haem in the liver?

    <p>The levels of haem in the system</p> Signup and view all the answers

    What condition may lead to hypoalbuminemia?

    <p>Impaired synthesis in the liver or chronic kidney disease</p> Signup and view all the answers

    What is the role of albumin in the blood?

    <p>It helps maintain oncotic pressure within the blood.</p> Signup and view all the answers

    What can result from increased renal excretion of albumin?

    <p>Fluid-induced swelling of extremities</p> Signup and view all the answers

    How is proalbumin converted to mature albumin?

    <p>Through cleavage of extensions in the Golgi apparatus</p> Signup and view all the answers

    Which of the following is NOT a function of globulins?

    <p>Energy storage</p> Signup and view all the answers

    What is the primary cause of edema as a result of hypoalbuminemia?

    <p>Decreased oncotic pressure in the blood</p> Signup and view all the answers

    What does haem transport in the blood?

    <p>Oxygen</p> Signup and view all the answers

    What is a consequence of lead poisoning on haem synthesis?

    <p>Inhibition of ALA synthase activity</p> Signup and view all the answers

    Which of the following correctly describes hyperalbuminemia?

    <p>Frequently associated with dehydration</p> Signup and view all the answers

    What is the consequence of impaired hepatic synthesis of plasma proteins?

    <p>Reduction in blood volume and potential edema</p> Signup and view all the answers

    Which statement is true regarding the regulation of albumin production?

    <p>Colloid pressure and inflammatory signals have an influence.</p> Signup and view all the answers

    What is a characteristic of globulin proteins?

    <p>They include components involved in the complement cascade.</p> Signup and view all the answers

    Which of the following is the main source of glucose when hepatic glycogen stores are depleted during fasting?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What is the role of insulin in carbohydrate metabolism?

    <p>It promotes glycogenesis and inhibits glycogenolysis.</p> Signup and view all the answers

    Which of the following statements about lipid metabolism in the liver is true?

    <p>Ketone bodies are synthesized in the liver and are used by other tissues for energy.</p> Signup and view all the answers

    Which of the following processes occurs in the liver during the metabolism of proteins?

    <p>Conversion of ammonia to urea for excretion</p> Signup and view all the answers

    What is the function of glycogenolysis?

    <p>To break down glycogen into glucose</p> Signup and view all the answers

    Which of the following liver functions is responsible for preventing ammonia toxicity?

    <p>Urea synthesis</p> Signup and view all the answers

    What is the primary function of Very Low-Density Lipoproteins (VLDLs) synthesized by the liver?

    <p>Exporting triglycerides, cholesterol, and phospholipids to other tissues</p> Signup and view all the answers

    Which of the following is NOT synthesized by the liver?

    <p>Insulin</p> Signup and view all the answers

    What is the primary function of albumin synthesized in the liver?

    <p>Maintaining oncotic pressure and transporting substances in the blood</p> Signup and view all the answers

    Which of the following substances is a product of the liver that is involved in blood coagulation?

    <p>Fibrinogen</p> Signup and view all the answers

    Which of the following substances is a product of the liver that is involved in blood coagulation?

    <p>Fibrinogen</p> Signup and view all the answers

    What is the main purpose of bile acids synthesized in the liver?

    <p>To aid in digestion and absorption of fats</p> Signup and view all the answers

    Nucleotide precursors synthesized by the liver are essential for:

    <p>DNA and RNA synthesis</p> Signup and view all the answers

    The synthesis of non-essential amino acids in the liver is primarily a result of:

    <p>Deamination and transamination reactions</p> Signup and view all the answers

    Urea, a product of the liver, serves what primary purpose in the body?

    <p>Excretion of nitrogenous waste</p> Signup and view all the answers

    Which of the following plasma proteins, synthesized in the liver, is primarily responsible for carrying fat-soluble nutrients, hormones, and drugs?

    <p>Albumin</p> Signup and view all the answers

    What is the primary function of apolipoproteins in the blood?

    <p>Transport of lipids in the blood</p> Signup and view all the answers

    Which plasma protein plays a major role in the regulation of blood coagulation?

    <p>Fibronectin</p> Signup and view all the answers

    Plasma proteins synthesized in the liver include which of the following?

    <p>Complement proteins and clotting factors</p> Signup and view all the answers

    Which of the following hormones, synthesized by the liver, plays a role in regulating metabolism and growth?

    <p>Insulin-like growth factor</p> Signup and view all the answers

    Which plasma protein is a key carrier protein that binds to and transports various hormones, drugs, and nutrients?

    <p>Albumin</p> Signup and view all the answers

    The liver synthesizes many clotting factors essential for blood coagulation. Which of the following is NOT one of those factors?

    <p>Albumin</p> Signup and view all the answers

    Which plasma proteins are involved in the body's immune response by activating the complement system?

    <p>Complement proteins</p> Signup and view all the answers

    Where is albumin synthesized?

    <p>Hepatic cells</p> Signup and view all the answers

    What is the primary function of albumin in the blood? A. Clot formation B. Transport of various substances and regulation of oncotic pressure C. Lipid metabolism D. Energy storage

    <p>Transport of various substances and regulation of oncotic pressure</p> Signup and view all the answers

    Which of the following substances is transported by albumin?

    <p>Exogenous drugs, bilirubin, and fatty acids</p> Signup and view all the answers

    What percentage of the oncotic pressure in the blood is contributed by albumin?

    <p>75-80%</p> Signup and view all the answers

    Which of the following properties of albumin is responsible for its ability to attract positively charged molecules and ions?

    <p>Negatively charged nature</p> Signup and view all the answers

    In addition to transporting substances, what other critical function does albumin perform in the blood?

    <p>Maintains blood pressure by regulating fluid distribution</p> Signup and view all the answers

    Which of the following conditions might result from decreased albumin levels in the blood?

    <p>Edema due to decreased oncotic pressure</p> Signup and view all the answers

    How much albumin is typically synthesized per day in a healthy adult?

    <p>15 g/day</p> Signup and view all the answers

    Oncotic pressure is primarily responsible for which of the following actions in the body?

    <p>Pulling fluid from the interstitium into the blood vessels</p> Signup and view all the answers

    What is the opposing force to oncotic pressure that influences the movement of fluid in the blood vessels?

    <p>Hydrostatic pressure</p> Signup and view all the answers

    Which of the following best describes the role of hydrostatic pressure in blood vessels?

    <p>Pushes fluid into the interstitium</p> Signup and view all the answers

    What happens to the volume of interstitial fluid when oncotic pressure increases?

    <p>It decreases</p> Signup and view all the answers

    In which situation might a decrease in albumin levels affect the body's fluid balance?

    <p>Decrease in oncotic pressure and fluid accumulation in the interstitium (edema)</p> Signup and view all the answers

    Hydrostatic pressure has which of the following effects on the interstitial fluid?

    <p>Increases the volume of interstitial fluid</p> Signup and view all the answers

    Which of the following conditions is most likely to cause impaired synthesis of albumin, leading to hypoalbuminemia?

    <p>Cirrhosis of the liver</p> Signup and view all the answers

    Hypoalbuminemia can result from increased renal excretion of albumin. Which condition is most associated with this cause?

    <p>Chronic kidney disease</p> Signup and view all the answers

    What is a common complication of hypoalbuminemia due to decreased oncotic pressure?

    <p>Pulmonary edema</p> Signup and view all the answers

    In nephrotic syndrome, hypoalbuminemia occurs due to:

    <p>Increased renal excretion of albumin</p> Signup and view all the answers

    What is albumin initially synthesized as?

    <p>Preproprotein</p> Signup and view all the answers

    How many amino acids are cleaved off during the processing of preproalbumin in the endoplasmic reticulum to form proalbumin?

    <p>18 amino acids</p> Signup and view all the answers

    In which cellular structure is proalbumin processed into mature albumin?

    <p>Golgi apparatus</p> Signup and view all the answers

    How many amino acids are removed from proalbumin in the Golgi apparatus to produce albumin?

    <p>6 amino acids</p> Signup and view all the answers

    Once albumin is synthesized, what happens to it?

    <p>Secreted immediately from the liver</p> Signup and view all the answers

    How much albumin is typically synthesized per day in a healthy adult?

    <p>15g</p> Signup and view all the answers

    The rate of albumin synthesis is primarily regulated by which of the following factors?

    <p>Colloid pressure, inflammatory mediators, and cortisol</p> Signup and view all the answers

    Which of the following correctly describes the role of cortisol in albumin synthesis?

    <p>Stimulates albumin production</p> Signup and view all the answers

    How many amino acids comprise the extension at the N-terminal end of preproalbumin?

    <p>24 amino acids</p> Signup and view all the answers

    What is the primary function of the 24 amino acid extension in preproalbumin?

    <p>To serve as a signal for directing the protein into the endoplasmic reticulum</p> Signup and view all the answers

    After the removal of the N-terminal extension from preproalbumin, what is the next form of the protein called?

    <p>Proalbumin</p> Signup and view all the answers

    How is albumin secreted from the liver?

    <p>By passing into liver sinusoids from hepatocytes</p> Signup and view all the answers

    What percentage of albumin remains in the blood after secretion?

    <p>40%</p> Signup and view all the answers

    What is the approximate half-life (T1/2) of albumin in the bloodstream?

    <p>17 days</p> Signup and view all the answers

    What is the daily degradation rate of albumin?

    <p>4%</p> Signup and view all the answers

    Which condition is associated with hyperalbuminemia?

    <p>Dehydration</p> Signup and view all the answers

    Under normal circumstances, albumin is not excreted in urine. What does its presence in urine typically indicate?

    <p>Kidney disease</p> Signup and view all the answers

    What is the second most abundant plasma protein in the blood?

    <p>Globulins</p> Signup and view all the answers

    How many types of globulins are there?

    <p>Three</p> Signup and view all the answers

    Which of the following globulins is primarily involved in immune function?

    <p>Gamma globulins</p> Signup and view all the answers

    Where are globulins synthesized?

    <p>In immune cells and the liver</p> Signup and view all the answers

    What is one of the key functions of globulins?

    <p>Clotting factors</p> Signup and view all the answers

    What can altered plasma levels of globulins indicate?

    <p>Malnutrition</p> Signup and view all the answers

    Which of the following is NOT a function of globulins?

    <p>Hormone production</p> Signup and view all the answers

    Which types of globulins are involved in transporting other substances in the blood?

    <p>Both A and B</p> Signup and view all the answers

    What disease can result from a deficiency in alpha-1 antitrypsin, a type of alpha globulin?

    <p>Emphysema</p> Signup and view all the answers

    What is heme?

    <p>A chemical in which iron is chelated in the center of a porphyrin ring</p> Signup and view all the answers

    Where is heme synthesized in the body?

    <p>In the liver, muscle, and bone marrow</p> Signup and view all the answers

    What is the color of heme when it is in its oxidized form?

    <p>Red</p> Signup and view all the answers

    Which of the following is a function of heme?

    <p>Oxygen transport</p> Signup and view all the answers

    Heme is an essential cofactor for which type of proteins?

    <p>Hemoproteins</p> Signup and view all the answers

    What role does heme play in myoglobin?

    <p>Oxygen storage</p> Signup and view all the answers

    Heme is involved in electron transport. Which of the following proteins utilize heme for this function?

    <p>Cytochromes</p> Signup and view all the answers

    Which enzymes are involved in antioxidation that contain heme?

    <p>Peroxidases and catalases</p> Signup and view all the answers

    Which of the following processes is NOT associated with heme?

    <p>Carbon metabolism</p> Signup and view all the answers

    What element is at the center of the heme structure?

    <p>Iron</p> Signup and view all the answers

    Where does the synthesis of heme begin in liver cells?

    <p>Mitochondria</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of glycine and succinyl CoA into aminolevulinic acid (ALA)?

    <p>ALA synthase</p> Signup and view all the answers

    After ALA is synthesized, where is it transported for further processing?

    <p>Cytoplasm</p> Signup and view all the answers

    Which enzyme converts aminolevulinic acid (ALA) into porphobilinogen (PBG)?

    <p>ALA dehydratase</p> Signup and view all the answers

    What does porphobilinogen (PBG) convert into?

    <p>Hydroxymethylbilane</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of hydroxymethylbilane to uroporphyrinogen (UPO)?

    <p>UPG synthase</p> Signup and view all the answers

    What is formed from the conversion of uroporphyrinogen (UPO) by UPG decarboxylase?

    <p>Coproporphyrinogen</p> Signup and view all the answers

    Where does coproporphyrinogen go after its synthesis?

    <p>It enters the mitochondria</p> Signup and view all the answers

    Which enzyme is responsible for chelating iron to protoporphyrin to form heme?

    <p>Ferrochelatase</p> Signup and view all the answers

    What is the primary factor regulating the rate of heme synthesis?

    <p>Heme levels</p> Signup and view all the answers

    How does heme regulate ALA synthase in hepatocytes?

    <p>It inhibits ALA synthase expression and activity</p> Signup and view all the answers

    Besides inhibiting ALA synthase, what other role does heme play in the body?

    <p>It stimulates globin synthesis</p> Signup and view all the answers

    Why is the balance between inhibition of ALA synthase and stimulation of globin synthesis important?

    <p>It maintains heme concentration in the body</p> Signup and view all the answers

    Which vitamin is essential for the synthesis of heme and is involved in the conversion of ALA to porphobilinogen?

    <p>Vitamin B6</p> Signup and view all the answers

    What can excessive levels of heme lead to in terms of regulation?

    <p>Decreased ALA synthase activity</p> Signup and view all the answers

    What is a common source of lead exposure that can lead to lead poisoning?

    <p>Lead-based paint</p> Signup and view all the answers

    Which of the following is a symptom of lead poisoning?

    <p>Anemia</p> Signup and view all the answers

    What is the mechanism by which lead causes heme synthesis defects?

    <p>Inhibition of ALA dehydratase and ferrochelatase</p> Signup and view all the answers

    Increased levels of which substance in the blood are associated with lead poisoning?

    <p>ALA (Aminolevulinic Acid)</p> Signup and view all the answers

    What type of anemia is typically associated with lead poisoning?

    <p>Microcytic anemia</p> Signup and view all the answers

    Which of the following therapies is commonly used to treat lead poisoning?

    <p>Chelation therapy (e.g., succimer, EDTA)</p> Signup and view all the answers

    Acute intermittent porphyria (AIP) is primarily characterized by:

    <p>Abdominal pain and neuropsychiatric symptoms</p> Signup and view all the answers

    Which of the following statements is true regarding lead poisoning?

    <p>It can lead to neurotoxicity due to increased ALA levels.</p> Signup and view all the answers

    What is the main cause of porphyrias?

    <p>Mutations in enzymes that synthesize heme</p> Signup and view all the answers

    What are the characteristic symptoms of porphyria? (Select the correct answer)

    <p>Abdominal pain, vomiting, confusion, and fever</p> Signup and view all the answers

    How does urine appearance change in patients with porphyria?

    <p>Becomes red/purple</p> Signup and view all the answers

    Which of the following can trigger porphyria attacks? A. High carbohydrate diet B. Hormonal changes and stress C. Regular exercise D. Antibiotic use

    <p>Hormonal changes and stress</p> Signup and view all the answers

    What is the biochemical basis of porphyrias?

    <p>Decreased heme production and accumulation of heme pathway intermediates</p> Signup and view all the answers

    Acute Intermittent Porphyria (AIP) is primarily characterized by which of the following?

    <p>Neuropsychiatric symptoms and abdominal pain</p> Signup and view all the answers

    What structural feature characterizes porphyrins?

    <p>Macrocyclic structures with four pyrrole rings</p> Signup and view all the answers

    What is the underlying defect in Acute Intermittent Porphyria (AIP)?

    <p>Defect in porphobilinogen deaminase</p> Signup and view all the answers

    Which of the following factors can trigger an attack of AIP? (Select all that apply)

    <p>Drugs that induce cytochrome P450 enzymes</p> Signup and view all the answers

    What is the main consequence of the defective heme synthesis pathway in AIP?

    <p>Accumulation of ALA and PBG</p> Signup and view all the answers

    What symptoms are commonly associated with Acute Intermittent Porphyria?

    <p>Seizures, psychosis, and severe abdominal pain</p> Signup and view all the answers

    What laboratory tests are used to diagnose Acute Intermittent Porphyria (AIP)?

    <p>Measure urinary ALA and PBG levels</p> Signup and view all the answers

    What treatment is used to manage Acute Intermittent Porphyria?

    <p>Haematin</p> Signup and view all the answers

    How does reduced heme levels affect ALA and PBG in AIP?

    <p>Increases ALA and PBG levels due to loss of negative feedback</p> Signup and view all the answers

    What is the role of cytochrome P450 enzymes in the context of AIP?

    <p>They are involved in drug metabolism and can trigger AIP attacks</p> Signup and view all the answers

    In the context of AIP, what is the significance of ALA accumulation?

    <p>It contributes to neurotoxicity and symptoms</p> Signup and view all the answers

    In the context of AIP, what is the significance of ALA accumulation?

    <p>It contributes to neurotoxicity and symptoms</p> Signup and view all the answers

    What is the underlying defect in Porphyria Cutanea Tarda (PCT)?

    <p>Defect in uroporphyrinogen decarboxylase</p> Signup and view all the answers

    What is a major consequence of the defect in uroporphyrinogen decarboxylase in Porphyria cutanea tarda (PCT)?

    <p>Accumulation of uroporphyrinogen (UPO) and decreased heme</p> Signup and view all the answers

    Why does uroporphyrinogen (UPO) cause skin damage in PCT?

    <p>It is photosensitive and becomes oxidized by sunlight</p> Signup and view all the answers

    What lifestyle modification is recommended for patients with PCT?

    <p>Avoid excess sunlight</p> Signup and view all the answers

    How can PCT be diagnosed?

    <p>Measure urinary uroporphyrinogen (UPO) levels</p> Signup and view all the answers

    Which medication can be used in the treatment of Porphyria Cutanea Tarda?

    <p>Anti-malarials such as chloroquine</p> Signup and view all the answers

    What is a common trigger for symptoms in patients with PCT? (Select one)

    <p>Excessive alcohol consumption</p> Signup and view all the answers

    What is a nickname often associated with Porphyria Cutanea Tarda due to its effects on the skin?

    <p>The Vampire Disease</p> Signup and view all the answers

    What is the role of haematin in treating porphyrias like Acute Intermittent Porphyria (AIP)?

    <p>Inhibits ALA synthase and restores the feedback inhibition of ALA production</p> Signup and view all the answers

    What happens when haematin is administered to a patient with porphyria?

    <p>It inhibits ALA synthase, reducing ALA and PBG levels</p> Signup and view all the answers

    Which of the following is an effect of using anti-malarials like chloroquine in porphyria treatment?

    <p>Binds to and increases urinary excretion of uroporphyrinogen</p> Signup and view all the answers

    Study Notes

    The Liver

    • Largest internal organ (1.5 kg)
    • Filters about 1.7 litres of blood per minute
    • Has two blood supplies: hepatic artery (from the heart) and portal vein (from the intestines)
    • Can regenerate itself if at least 25% of the healthy liver remains
    • Performs over 500 vital functions

    Liver Functions

    • Metabolism
      • Carbohydrate metabolism:
        • Stores glucose as glycogen (glycogenesis)
        • Breaks down glycogen when glucose levels are low (glycogenolysis)
        • Produces glucose from non-carbohydrate sources (gluconeogenesis)
      • Lipid metabolism:
        • Oxidizes triglycerides for energy
        • Converts fatty acids to ketone bodies
        • Synthesizes cholesterol and phospholipids
        • Creates lipoproteins
      • Protein metabolism:
        • Deaminates and transaminates amino acids
        • Removes ammonia by converting it to urea
        • Synthesizes non-essential amino acids
        • Produces plasma proteins like albumin and clotting factors
    • Excretion and detoxification
      • Removes bilirubin, ammonia, cholesterol, steroid hormones, drugs, and toxins

    Biosynthetic Products of the Liver

    • Nutrients:
      • Triglycerides, cholesterol, phospholipids, lipoproteins
      • Glycogen, glucose
      • Non-essential amino acids
    • Other:
      • Plasma proteins (e.g., albumin, globulins)
      • Haem
      • Clotting factors (fibrinogen)
      • Bile acids
      • Nucleotide precursors
      • Urea

    Albumin

    • Most abundant protein in serum
    • Negatively charged, attracts positively charged molecules and ions
    • Functions:
      • Transports substances in the blood (bilirubin, fatty acids, metals, ions, hormones, drugs)
      • Regulates fluid distribution between blood and tissues
    • Control of blood volume:
      • Contributes to blood oncotic pressure
      • Hypoalbuminemia (low albumin) can lead to edema (swelling) and ascites (fluid build-up in the abdomen)

    Albumin Synthesis & Distribution

    • Synthesized as a preproprotein, processed in the endoplasmic reticulum and Golgi apparatus
    • Secreted directly into liver sinusoids
    • Half-life of about 17 days
    • Degradation rate of about 4% per day
    • Levels can be measured in blood (hyperalbuminemia due to dehydration, hypoalbuminemia due to liver disease, kidney disease, etc.)

    Globulins

    • Second most abundant plasma protein, three types: alpha, beta, gamma
    • Synthesized in the liver and immune cells
    • Functions:
      • Transport other substances
      • Enzymatic activity
      • Clotting factors
      • Immune function (gamma globulins)
      • Exert oncotic pressure
    • Altered plasma levels can indicate disease

    ### Plasma Proteins - Summary

    • Synthesized in the liver (e.g. Albumin, Globulins)
    • Transport lipophilic substances in the blood
    • Maintain fluid homeostasis
    • Impaired synthesis leads to edema and ascites

    Haem Synthesis

    • Contains iron in a porphyrin ring
    • Synthesized in the liver, muscle, and bone marrow
    • Essential cofactor for haemoproteins (oxygen transport, storage, metabolism, electron transport)

    Haem Biosynthetic Pathway

    • Haem synthesis is regulated by haem levels:
      • Haem inhibits ALA synthase expression and activity, stimulates globin synthesis
    • Defects in haem synthesis:
      • Lead poisoning
      • Porphyrias

    Lead Poisoning

    • Exposure to lead in paint, dust, batteries, etc.
    • Symptoms: Anemia, constipation, abdominal pain, seizures, coma
    • Mechanism: Inhibits ALA dehydratase and ferrochelatase
    • Therapy: Remove the source, chelation therapy (e.g., succimer, EDTA)

    Porphyrias

    • Group of liver disorders leading to porphyrin accumulation
    • Usually hereditary, caused by mutations in haem synthesis enzymes
    • Causes: Decreased haem production, build-up of porphyrins
    • Symptoms: Abdominal pain, vomiting, confusion, fever, constipation, seizures
    • Subtypes due to different deficient enzymes

    Acute Intermittent Porphyria (AIP)

    • Defect in porphobilinogen deaminase
    • Attacks triggered by drugs, stress, etc.
    • Accumulation of ALA and PBG
    • Symptoms: Seizures, psychosis, severe abdominal pain, coma
    • Treatment: Haematin (synthetic form of haem)

    Porphyria Cutanea Tarda (PCT)

    • Defect in uroporphyrinogen decarboxylase
    • Causes: Build-up of uroporphyrinogen and decreased haem
    • UPO accumulates near the skin
    • UPO is photosensitive and becomes oxidised by sunlight
    • Oxidized UPO causes cell damage, inflammation, blistering, and discoloration
    • Treatment: Avoid sunlight, alcohol, and iron supplements. Use antimalarials (e.g., chloroquine)

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    Description

    Test your knowledge about the liver, the largest internal organ and its vital functions ranging from metabolism to blood filtration. This quiz will cover key aspects such as carbohydrate, lipid, and protein metabolism. Discover how the liver maintains homeostasis and contributes to overall health.

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