Obstructive Jaundice and Related Disorders
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Questions and Answers

What is a primary cause of obstructive (posthepatic) jaundice?

  • Autoimmune disease
  • Mechanical obstruction in bile flow (correct)
  • Viral infection
  • Excessive alcohol consumption

    • Conjugated hyperbilirubinemia is characteristic of obstructive jaundice.

    True

    Name the two types of pulmonary pigment deposition disorders mentioned.

    Anthracosis and siderosis

    Urobilinogen is reduced by bacteria in the intestines and is eventually excreted in _____ and oxidized to form urobilin and stercobilin.

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

    Match the following exogenous pigments with their descriptions:

    <p>Anthracosis = Deposition of carbon or coal dust in the lungs Siderosis = Deposition of iron in the lungs</p> Signup and view all the answers

    Which of the following substances can accumulate in cells as a result of an exogenous source?

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

    Fatty liver can be considered a reversible condition if the cause contributing to the fatty accumulation is removed.

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

    What is the main organ involved in fat metabolism where fatty change is commonly observed?

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

    Obesity and a deficiency of ______ factors can lead to the accumulation of neutral fats in body tissues.

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

    Match the following conditions with their descriptions:

    <p>Lysosomal storage diseases = Result from genetic defects in metabolism Anthracosis = Accumulation of carbon particles in lungs Silicosis = Accumulation of silica in the lungs Jaundice = Yellowing of skin due to bile pigment accumulation</p> Signup and view all the answers

    Which of the following factors can NOT directly lead to fatty liver?

    <p>Excessive protein intake</p> Signup and view all the answers

    An increased rate of production of a normal substance can sometimes lead to its accumulation if the metabolic rate is adequate for removal.

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

    Name one important hepatotoxin in humans that can cause fatty liver.

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

    Which of the following pigments is an endogenous pigment produced in the body?

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

    In horses, the liver appears orange due to the natural color of fat.

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

    What is the major pigment found in bile?

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

    The condition known as _____ occurs when there is an increase in bilirubin levels in the blood.

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

    Match the following items with their corresponding descriptions:

    <p>Melanin = Black or brown pigment produced from tyrosine Albinism = Complete absence of melanin pigment Hemosiderin = Golden yellow to brown pigment from hemoglobin Jaundice = Yellow discoloration of skin due to elevated bilirubin levels</p> Signup and view all the answers

    What condition is caused by excess iron in the body?

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

    Unconjugated bilirubin is soluble in water and non-toxic to tissues.

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

    What are the two types of bilirubin found in the blood?

    <p>Conjugated and unconjugated bilirubin</p> Signup and view all the answers

    _____ is a localized loss of pigment affecting only certain body areas.

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

    Which enzyme is responsible for converting biliverdin to bilirubin?

    <p>Biliverdin reductase</p> Signup and view all the answers

    Melanosis is characterized by the presence of melanocytes in various internal organs.

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

    What is the role of melanocytes in the skin?

    <p>To produce melanin</p> Signup and view all the answers

    The pigment that appears as clear vacuoles in cells during fatty liver is mainly _____.

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

    Which condition is described by an increased amount of melanin in the skin?

    <p>Acanthosis nigricans</p> Signup and view all the answers

    Bilirubin is derived from the iron component of hemoglobin.

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

    Study Notes

    Intracellular Accumulations

    • Cells can accumulate abnormal amounts of substances, which can be harmless or cause injury.
    • Substances can accumulate in the cytoplasm, organelles (like lysosomes), or the nucleus.
    • Three pathways can lead to abnormal accumulation:
      • A normal substance is produced at a normal or increased rate, but the metabolic rate to remove it is inadequate. An example is fatty change in the liver.
      • A normal or abnormal endogenous substance accumulates due to a genetic or acquired defect in metabolism, transport, or secretion. An example is lysosomal storage diseases.
      • An abnormal exogenous substance may accumulate because the cell lacks the enzymes to degrade the substance or the ability to transport it elsewhere. Examples include carbon (anthracosis) or silica (silicosis) deposits in the lungs.

    Fatty Change

    • Abnormal accumulation of neutral fat within parenchymal cells.
    • It is a reversible change, but if the cause isn't removed, it can lead to cell death.
    • Most commonly seen in the liver, which is the major organ involved in fat metabolism.
    • Can also be seen in the heart and kidneys.
    • Various irritants, including hepatotoxins (both organic and inorganic), bacterial toxins, plant toxins, and chemical toxins (including alcohol), can cause fatty change.

    Metabolic Diseases

    • Diseases like diabetes mellitus can lead to intracellular accumulations.
    • Deficiency of lipotropic factors (like choline, which is needed for transforming neutral fat into phospholipids) can reduce the transformation of neutral fats and cause their accumulation in body tissues.
    • Methionine is a choline precursor and is a lipotropic factor.
    • Obesity can also be a factor.

    Pathogenesis of Fatty Liver

    • Abnormal accumulation of triglycerides or neutral fats in the liver.
    • Accumulation can result from defects in these different events:
      • Excessive entry of fatty acids into the cell.
      • Enhanced fatty acid synthesis.
      • Increased esterification of fatty acids to triglycerides.
      • Decreased apoprotein synthesis. Apoproteins are needed for converting triglycerides to lipoproteins for excretion from the cells.
      • Impaired lipoprotein secretion from the cell.

    Macroscopic Appearance of Fatty Liver

    • The liver is most commonly affected.
    • The liver appears yellow, but the color depends on the animal species' natural fat color.
    • In cats, it's white; in cattle, yellow; and in horses, orange.
    • The liver's borders become rounded as it enlarges.
    • The liver's consistency becomes soft and greasy.
    • The liver is easily ruptured, and its cut surface bulges outwards with a greasy appearance.

    Microscopic Appearance of Fatty Liver

    • Small, clear vacuoles of varying sizes are seen in the cytoplasm.
    • The vacuoles can combine to form larger ones, indicating severe or chronic injury.
    • Water and glycogen can also be seen as clear vacuoles.
    • Specific stains (Oil Red-O or Sudan IV) help identify fat.
    • Periodic Acid-Schiff (PAS) reaction is used to identify glycogen.

    Pigmentation

    • Pigments are colored substances found in cells.
    • Some are normal, like melanin, which gives skin color.
    • Pigments can be endogenous (synthesized within the body) or exogenous (from outside).
      • Endogenous pigments include melanin, lipofuscin, and hemoglobin derivatives.

    Melanin

    • Melanin is a brown to black pigment made in melanocytes.
    • Tyrosinase enzyme oxidizes tyrosine amino acid to produce melanin.
    • Melanocytes are in the epidermis' basal layer.
    • Melanin is stored in granules within the epithelial cells of the stratum germinativum.
    • Melanin's color (black, brown, or red) depends on its concentration and distribution in the skin.
    • Melanin protects against harmful ultraviolet rays.
    • Cells storing melanin are called melanophores.
    • Melanosis can occur in various internal organs, including intestines, lungs, and heart, during early development. This condition can cause blindness in certain dog breeds.
      • Excessive melanin can be seen in some tumors (melanomas/melanocarcinomas).
      • Acanthosis nigricans is an increased amount of melanin in the skin.
      • Albinism is the complete absence of melanin due to inherited deficiency in the tyrosinase enzyme.
      • Other conditions exist such as vitiligo or leukoderma, where specific areas lack pigment in the skin

    Derivatives of Hemoglobin

    • Erythrocytes (red blood cells) live about 120 days.
    • They break down in the spleen, liver, and bone marrow (mononuclear phagocytic cells).
    • Hemoglobin breaks down into globin (recycled), iron (stored as ferritin or hemosiderin), and heme.
    • Iron is stored as ferritin. When iron levels are high, it forms hemosiderin granules.

    Hemosiderin

    • Golden yellow to brown pigment derived from hemoglobin.
    • Local accumulation occurs from local hemorrhages (like bruises).
    • Systemic accumulation is known as hemosiderosis.
    • It can be related to increased iron intake or decreased iron utilization (e.g., hemolytic anemia).

    Bilirubin

    • A pigment derived from hemoglobin that lacks iron.

    • The major pigment in bile.

    • About 70% of bilirubin originates from the destruction of red blood cells (RBCs) in the liver, spleen, and bone marrow.

    • Remaining 30% comes from other heme proteins (hemoproteins).

    • Hemoglobin is broken down into biliverdin, which is converted to bilirubin.

    • Bilirubin is transported in the blood, bound to albumin, to the liver.

    • In the liver, bilirubin is conjugated to glucuronic acid and secreted into bile.

    • In the intestine, bacteria convert bilirubin to urobilinogen and stercobilin.

    • Some urobilinogen is reabsorbed into the bloodstream, returned to the liver, and re-excreted in the bile.

    • Remaining urobilinogen is converted to urobilin, which is excreted in urine (giving it color).

    • Also, some urobilinogen and stercobilin are excreted in the feces (giving it color).

    Jaundice

    • Jaundice is the yellowing of the skin and sclera due to elevated bilirubin levels in the blood (hyperbilirubinemia).
    • Bile pigments may also be excreted in the urine.
    • There are three types of jaundice: prehepatic (hemolytic), hepatic (toxic), and posthepatic (obstructive).
      • Prehepatic jaundice occurs from increased destruction of red blood cells.
      • Hepatic jaundice arises from impaired liver function.
      • Posthepatic jaundice occurs from obstruction of bile flow.

    Exogenous Pigments

    • Pigments originating from outside the body.
    • Lungs and their lymph nodes hold various dust particles.
    • Lung disorders from dust inhalation are called pneumoconiosis (often occupation-related).
      • Anthracosis: Carbon (coal dust) accumulation in the lungs.
        • Siderosis: Iron accumulation in the lungs.
        • Silicosis: Silicon or stone dust accumulation in the lungs, which can cause severe fibrosis and a predisposition to tuberculosis.

    Mineral Deposits

    • Pathological calcification occurs when minerals (especially calcium) deposit in tissues.
    • Dystrophic calcification – abnormal areas; in degenerating or necrotic tissue.
    • Metastatic calcification – secondary to some primary condition, such as hyperparathyroidism or abnormal vitamin D function.

    Renal disease, high vitamin D intake, may also contribute.

    Gout

    • Gout is a metabolic disorder characterized by elevated uric acid levels in the blood.
    • The body forms uric acid from purine metabolism.
    • Excess uric acid can crystallize in joints and tissues (like synovium).
    • This formation of crystals triggers inflammation, pain, and joint damage.
    • Crystal formation initiates inflammation, resulting in joint injury.
    • Macrophages then release enzymes and other mediators that exacerbate the inflammatory response and contribute to joint damage.

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    Description

    This quiz covers important concepts related to obstructive jaundice, including its causes and characteristics such as conjugated hyperbilirubinemia. Additionally, it explores pulmonary pigment deposition disorders and related biochemical processes, including the role of urobilinogen. Test your knowledge and understanding of these medical topics.

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