Cell Pathology 2 Flashcards
Effects of cell death
• Loss of ability to divide
• Loss of normal synthetic functions
• Biochemical changes, followed by structural changes
Cell death characteristics in necrosis
-membrane blebbing
-blebs fuse and become larger
-cell membrane ruptures and releases the cells content
Cell death characteristics in apoptosis
-smell blebs form
-nucleus begins yo break apart and dna breaks into small pieces(organelles are also located in the blebs)
-the cell breaks into several apoptopic bodies;the organelles are still functioning
Nuclear changes in cell death
Pyknosis(nuclear shrinkage)
Karyolysis(nuclear fading|)
Karyorrhexis(nuclear fragmentation)
Necrosis
• Necrosis is caused by factors external to the cell or tissue e.g. infections, toxins or trauma
• It results in unregulated digestion of the cell components
• Loss of cell membrane integrity and uncontrolled release
of products of cell death brought about by autolysis • Inflammatory response in the surrounding tissue
Tissue Response to Necrosis
-Haemorrhage
-Resolution
• Site, type and extent of injury
• If cannot resolve, body attempts to repair
-Repair
• Removal of dead tissue
• Action of neutrophils and macrophages • Granulation tissue
Types of necrosis
• Coagulative necrosis
• Liquefaction (colliquative necrosis) • Caseating necrosis
• Fat necrosis
• Gangrenous necrosis
Coagulative necrosis
• Most common
• Affects solid organs
• Artery occlusion → ischaemia is most common cause(lack of blood flow)
• Firm and pale
• Cellular outline and tissue architecture maintained
• Lack of lysosomes/ injury destroys lysosomal enzymes
Colliquative or Liquefactive Necrosis
• Semi-liquid
• Degradation of cellular and extracellular components by hydrolytic enzymes
• Cystic cavities containing fluid and cell debris
• Main causes include cerebral infarction or bacterial infection
• Loss of neurones
• Many macrophages clearing cell debris
Caseating Necrosis
Soft and white – resembling cream cheese
• Unstructured protein mass
• Associated by tuberculosis
Fat Necrosis
• Hard yellow material seen in dead adipose tissue
• Pancreatitis → release of proteolytic & lypolytic enzymes
• Breast trauma → release of fatty acids → inflammatory response
Calcification of Necrotic Tissue
Dystrophic calcification
➢Large amounts of calcium enter the cell
➢Combine with phosphate to form crystals ➢Extracellular calcification can also occur
Gangrene
• Not a distinctive type of necrosis
• Describes black dead tissue
• Most common in lower limb of patients with severe atherosclerosis
• Irreversible ischaemic damage
Types of Gangrene
- Dry gangrene
→Coagulative pattern of necrosis - Wet gangrene
→ Gram-negative bacteria converts it to liquefactive
necrosis - Gas gangrene
→Follows infection with gram-positive organism
Clostridium welchii (found in the soil) →Releases toxins which produce gas
Dry Gangrene
• Coagulative necrosis from ischaemic injury
• Commonly caused by poor circulation or obstruction • Slow, gradual process
• Usually seen in smokers, diabetics, atherosclerosis
