Cell Accumulation Quiz: Pathology Overview

Intracellular Accumulations

• Cells may accumulate abnormal substances, which can be harmless or lead to varying degrees of injury.
• Substances can accumulate in the cytoplasm, within organelles (especially lysosomes), or in the nucleus.
• Substances can be synthesized by the affected cells or produced elsewhere.

Types of Intracellular Accumulations

• Normal cellular constituents:
  • Lipids (e.g., triglycerides)
  • Proteins
  • Carbohydrates
• Abnormal substances:
  • Exogenous (from outside the body)
  • Endogenous (from inside the body)
• Pigments:
  • Exogenous
  • Endogenous

Pathways of Abnormal Intracellular Accumulation

• Abnormal metabolism:
  • Normal substance is produced at a normal or increased rate, but the metabolic rate is inadequate to remove it (e.g., fatty change in the liver).
• Alterations in protein folding and transport:
  • Normal or abnormal substance accumulates due to genetic or acquired defects in folding, packaging, transport, or secretion (e.g., α1-antitrypsin deficiency).
• Deficiency of critical enzymes:
  • Inherited enzyme defect leads to failure to degrade a metabolite, causing storage diseases.
• Inability to degrade phagocytosed particles:
  • Abnormal exogenous substances accumulate because the cell lacks the enzymes to degrade them or the ability to transport them to other sites (e.g., carbon or silica particles).

Specific Intracellular Accumulations

• Hydropic change (Water accumulation):
  • Often occurs in response to cell injury
• Fatty change (Steatosis):
  • Abnormal accumulation of triglycerides within parenchymal cells.
  • Caused by an imbalance between uptake, utilization, and secretion of fat.
  • Commonly seen in the liver, but can also occur in the heart, kidney, skeletal muscle, and other organs.
  • Can be mild and reversible or severe and irreversible, leading to cell death.
  • Common causes include:
    • Alcohol consumption
    • Diabetes
    • Obesity
    • Toxins
• Proteins:
  • Abnormal protein accumulation is often irreversible.
• Glycogen:
  • Glycogen storage diseases are caused by enzyme deficiencies.
• Complex carbohydrates:
  • Mucopolysaccharidoses and other complex carbohydrate diseases.
• Minerals:
  • Iron as hemosiderin
  • Carbon as anthracotic pigment
• Pigments:
  • Exogenous (e.g., carbon)
  • Endogenous (e.g., melanin, lipofuscin)
• Calcium:
  • Can be deposited in tissues, causing calcification.
• Amyloid:
  • Abnormal protein deposits that can accumulate in various tissues.

Fatty Liver

• Most common cause: Alcohol abuse
• Mechanisms:
  • Excessive entry of free fatty acids into the liver
  • Enhanced fatty acid synthesis
  • Decreased catabolism of triglycerides
  • Increased esterification of fatty acids to triglycerides
  • Decreased apoprotein synthesis
  • Impaired lipoprotein secretion from the liver

Morphology of Fatty Liver

• Grossly:
  • Enlarged, yellow, and/or greasy (depending on severity)
• Microscopically:
  • Fat is seen as small droplets or large vacuoles in the cytoplasm.
  • Vacuoles displace the nucleus to the periphery of the cell.
  • Vacuoles appear clear with well-defined edges.

Cholesterol and Cholesterol Esters

• Cholesterol:
  • Used for cell membrane synthesis.
• Accumulation:
  • Can occur in macrophages (foam cells) and foreign body giant cells in various pathologic conditions.
  • Accumulation is manifested as intracellular vacuoles.
• Conditions associated with cholesterol and cholesterol ester accumulation:
  • Atherosclerosis
  • Acquired and hereditary hyperlipidemia
  • Inflammation and necrosis

Atherosclerosis

• Smooth muscle cells and macrophages:
  • Filled with lipid vacuoles containing cholesterol and cholesteryl esters in the arterial walls.
• Pathogenesis:
  • Contribute to the development of atherosclerotic plaques.
  • Give the plaques their characteristic yellow color.

Test your knowledge on intracellular accumulations in cells. This quiz covers various types of abnormalities, their origins, and implications on cell health and function. Dive into concepts involving normal constituents, abnormal substances, and metabolic pathways.