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Questions and Answers
What is the primary cause of coagulative necrosis?
What is the primary cause of coagulative necrosis?
- Mechanical injuries leading to cell rupture
- Infectious agent damage to tissues
- Digestion and liquefaction of necrotic tissue
- Denaturation of structural and enzymic proteins (correct)
Which of the following appearances is characteristic of necrotic tissue in liquefactive necrosis?
Which of the following appearances is characteristic of necrotic tissue in liquefactive necrosis?
- Firm and cooked meat appearance
- Cavity filled with pus (correct)
- White, gray or yellow coloration
- Sharp demarcation from healthy tissue
Which microscopic change is commonly seen in necrotic cells?
Which microscopic change is commonly seen in necrotic cells?
- Cellular elongation
- Increased cell membrane integrity
- Disappearance of the nucleus (karyolysis) (correct)
- Decreased eosinophilia
What appearance might an area of gangrene exhibit?
What appearance might an area of gangrene exhibit?
Which factor is NOT identified as a general cause of necrosis?
Which factor is NOT identified as a general cause of necrosis?
What type of necrosis is characterized by the preservation of structural outlines while cellular details are lost?
What type of necrosis is characterized by the preservation of structural outlines while cellular details are lost?
What is pus primarily composed of in the context of necrosis?
What is pus primarily composed of in the context of necrosis?
Which of the following is a characteristic gross appearance of coagulative necrosis?
Which of the following is a characteristic gross appearance of coagulative necrosis?
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Study Notes
Necrosis Overview
- Necrosis refers to the death of cells and tissues in a living organism.
- Major causes include poisons (e.g., strong acids, insecticides), infectious agents (bacteria like Salmonella, viruses, fungi), circulatory issues (anemia, ischemia), mechanical injuries, and physical factors (extreme temperatures, electricity).
Gross Appearance of Necrotic Tissue
- Affected areas may appear white, gray, or yellow.
- Characteristic "cooked meat" appearance.
- Necrotic tissue is sharply demarcated from healthy tissue by a red zone.
- In gangrene, affected areas can be green, orange, or black due to iron sulfide.
Microscopic Appearance of Necrotic Tissue
- Cytoplasmic changes include eosinophilia (dark red staining), swelling, and vacuolation.
- Nuclear changes can involve condensation (pyknosis), fragmentation (karyorrhexis), or total disappearance (karyolysis).
Types of Necrosis
Coagulative Necrosis
- Most common type, where the structural outlines of tissue persist but cellular details are lost.
- Recognizable type of tissue due to denaturation of structural and enzymatic proteins, blocking proteolysis.
- Grossly appears firm, with a cooked meat look, distinctly separated from healthy tissue.
- Microscopic view shows preserved outlines but no cellular details; dead tissues can remain for extended periods before being removed by macrophages.
Liquefactive Necrosis
- Involves digestion and liquefaction of necrotic tissue.
- Gross appearance features a liquefied necrotic area filled with semisolid pus, a thick exudate of leukocytes, tissue debris, and microorganisms.
- Proteolytic enzymes from neutrophils are responsible for cell liquefaction.
- Abscess formation can occur, characterized by a localized collection of pus encased in a fibrous capsule.
- On microscopy, no structural or cellular details are visible, appearing as a cavity filled with necrotic neutrophils, bacteria, and tissue debris.
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