Lecture Notes: Morphology of Necrosis

Overview

• Discussing the morphology of necrosis, a point where cells can no longer repair themselves and return to homeostasis.
• Examination from microscopic and gross perspectives.

Key Terms Related to Necrosis

1. Karyolysis
   • Chromatin in the nucleus deteriorates and disappears.
2. Pyknosis
   • Nucleus becomes small and condensed.
3. Karyorrhexis
   • Nucleus fragments into pieces.

Types of Tissue Necrosis

1. Coagulative Necrosis

• Characteristics:
  • The structure of the tissue remains intact.
  • Structural proteins and enzymes are denatured.
  • Leukocytes and phagocytes gradually destroy the necrotic tissue.
• Causes:
  • Typically due to ischemia (loss of blood flow).
• Example:
  • Myocardial infarction (heart attack) where blood supply to a part of the heart is blocked.

2. Liquefactive Necrosis

• Characteristics:
  • Tissue turns into a liquid form.
  • Typically yellowish and presents with pus.
• Causes:
  • Often due to bacterial infection.
  • Occurs in the central nervous system (CNS) even in the presence of ischemia.

3. Gangrenous Necrosis

• Types:
  • Dry Gangrene: Coagulative necrosis due to lack of blood flow.
  • Wet Gangrene: When bacterial infection leads to liquefactive necrosis.
• Location:
  • Usually occurs in the lower limbs.
• Process:
  • Blood flow is compromised, allowing bacterial infection to cause necrosis.