Necrosis Flashcards
Necrosis
Death of a substantial number of cells within or attached to the living body
Pyknosis
Nuclear structure becomes dense, heavily stained, with smaller angular mass of chromatin.
Karyorrhexis
Nucleus has broken up into several pieces
Karyolysis
Nuclear staining with haematoxylin becomes faint and only the ghost outline of the nucleus remains
Cytoplasm
Sometimes stains brighter pink (more eosinophilic)
Three main causes of necrosis
Loss of blood supply, living agents, and non-living agents.
Hypoxia
reduced oxygen supple
Ischaemia
Loss of blood supply
Infraction
Sudden loss of blood supply to a portion of a tissue or organ
Parenchyma
Essential functioning cells
Stroma
Connective tissue or supportive cells
Three ways ischemia occurs
Compression, narrowing, blockage
Atherosclerosis
Narrowing, thickening, and hardening of vessel lumen or wall. Rare in animals.
Thrombus
Blood clot
Embolism
Blood clot breaks off and getting lodged somewhere in the body.
Examples of Ischaemia
Diamond Skin Disease and Ergot fungus
Three Zones of Necrotic Lesions
Normal liver, zone of inflammation, central zone of necrosis
Features of necrotic tissues
Color change and consistency
Three main types of gross necrosis
Coagulative, liquefactive, caseous
Fat necrosis
hard soap-like appearance of affected body fat
Gangrene
Post necrotic change
Coagulative Gross Necrosis
Retains the structure of the tissue but has a color change. Firm and dry
Liquefactive Gross Necrosis Types
Malacia and abscesses
Malacia
Thiamine deficiency in the CNS
Abscess
Pyogenic spots produced by death of neutrophils
Pyogenic
Pus producing
Caseous Necrosis
Looks like cottage cheese. Complete loss of architecture cause by mycobacteria attacking macrophage
Surface Necrosis Basement Membrane Intact
Epithelium regenerates via erosion
Surface Necrosis Basement Membrane Breached
Repair by fibrosis via ulceration. Inflammatory response.
Internal Necrosis
Repaired or contained by fibrous tissue
Surface Necrosis
Can be shed
Three types of fat necrosis
Enzymatic, traumatic, diet-related
Two types of Gangrene
Wet and dry
Wet Gangrene
Primary and secondary
Primary Wet Gangrene
Agent which kills tissue also putrefies it
Secondary Wet Gangrene
Dead tissue is putrefied by other organisms
Dry Gangrene
Leathery mummification on extremities when air removes fluid on dead tissue
