Cell injury & Postmortem changes Flashcards
Cell Injury
Rank the following cells by their sensitivity to injury
- Fibroblasts / Skeletal muscles
- Neurons
- Cardiomyocytes / Hepatocytes / Renal epithelium
Neurons > Cardiomyocytes / Hepatocytes / Renal Epithelium > Fibroblasts / Skeletal muscles
Mechanisms of cell injury
What happens to cellular mitochondria when Hypoxia (Inadequate of O2) happens?
(D) means decrease. (I) means increase
Oxidative phosphorylation (D)
ATP (D)
What are the 3 things that happens when cellular ATP decreases?
Na+/K+ pump fails
Anaerobic glycolysis (I)
Detachment of ribosomes
What happens to the cell if Na+/K+ pump fails due to the lack of ATP? (1)
Intracellular Na+ (I) which also brings in H2O
-> ER swelling, Cellular swelling
-> Extensive vacuolation
What happens to the cell if Na+/K+ pump fails due to the lack of ATP? (2)
Influx of Na+
-> Influx of Ca2+
Cytosolic Ca2+ activates cellular enzymes
Phospholipase -> Phospholipids (D) [Membrane damage]
Protease -> Cytoskeletal proteins (D) [Membrane damage]
Endonuclease -> Cleave between nucleosomes [Nuclear damage]
ATPase -> ATP (D)
What happens when a cell undergoes anaerobic glycolysis due to the lack of ATP?
Lactic acid is produced
-> pH (D)
-> Clumping of nuclear chromatin
What happens when detachment of ribosomes happens due to the lack ATP?
RNA translation (D)
-> Protein synthesis (D)
Other than Hypoxia which causes ATP depletion, what are the other mechanism of cell injury?
Free radicals
Increased membrane permeability
Mitochondrial damage
Apoptosis
What are the 3 main sites of free radical damage?
Membrane
Proteins
DNA
What causes the increase of membrane permeability?
Free radicals
Hypoxia
-> Decrease in phospholipid & protein synthesis
-> Cytosolic Ca2+ (I)
-> Phospholipase activation
-> Protease activation
Is acute cell swelling a reversible or irreversible cell injury?
Reversible cell injury
Morphology of acute cell swelling
What is the 3 microscopic appearances of acute cell swelling?
Cloudy swelling
Hydropic degeneration
Ballooning degeneration
What are the 4 histologic changes of nucleus in necrosis?
Pyknosis : Shrunken & darken nucleus
Karyorrhexis : Ruptured nucleus
Karyolysis : Pale nucleus due to the dissolution of chromatin by DNAases & RNAases
Absence of nucleus
What are the 5 types of necrosis?
Coagulative necrosis
Liquefactive necrosis
Caseous necrosis
Gangrenous necrosis
Fat necrosis
What is coagulative necrosis?
Denatures both structural proteins and hydrolytic enzyme
-> Outline of cell persists
Essentially coagulative necrosis primarily involves denaturation of structural proteins rather than the activation of hydrolytic enzymes
What are the names for skeletal /muscular acute cell swollen & coagulative necrosis?
And what are the properties of it?
Zenker’s degeneration & Zenker’s necrosis
Zenker’s degeneration : Swollen & vacuolation of muscle fibers. Hyalinization
Zenker’s necrosis : Fragmentation of myofibers. Loss of cross striations
What is liquefactive necrosis?
Activation of hydrolytic enzyme
-> Enzymatic digestion of necrotic cells
Usually bacterial infection
-> Abcess
-> Attraction of neutrophils which contains hydrolases
Hypoxic damage of brain / spinal cord
-> Enzymatic dissolution of neurons
-> Lack of fibrous connective tissues
-> Liquefactive necrosis
What is caseous necrosis?
Formation of granuloma consisting lymphocytes and multi- nucleated macrophage.
Classic cause is by tuberculosis and Corynebacterium
Often associated with slow and persistence infection
What is gangrenous necrosis?
Necrosis of extremities
Usually caused by hypoxia
What are the 3 types of gangrenous necrosis?
Dry gangrene
Moist gangrene
Gas gangrene
What are the difference between dry and moist gangrene?
(Location, cause)
Dry gangrene usually occurs in extremities caused by toxins or cold
Moist gangrene usually occurs in organs and is infected by putrefactive bacteria
What is gas gangrene?
It is the production of gas bubbles caused by infection of bacteria, especially Clostridia
What is fat necrosis?
Necrosis of fatty tissue, especially subcutaneous fat and adipose tissue
What are the names of the 2 pathway in apoptosis?
Extrinsic ( Receptor - initiated ) pathway
Intrinsic ( Mitochondrial ) pathway
What is the main caspase for apoptosis?
And what are the caspases for extrinsic and intrinsic pathway?
Main : Caspase 3
Extrinsic : Caspase 8
Intrinsic : Caspase 9
Is inflammation present or absent during apoptosis?
absent
Which are the 2 receptor-ligand interactions for extrinsic pathway?
Fas
TNF receptor
What are the 2 receptor - ligand interaction in extrinsic apoptosis pathway?
Fas
TNF
In hypoxia, what does cyanide poisoning do to interfere with oxidative phosphorylation?
Cyanide poisoning inactivates cytochrome oxidase in mitochondria
Morphologic appearance of postmortem changes
What is Autolysis?
Self - digestion of cells by hydrolytic enzymes
Morphologic appearance of postmortem changes
What is putrefaction?
Postmortem bacterial metabolism
-> Production of color
-> Texture change
-> Production of gas ( Ruminant forestomach & equine cecum )
-> Odors
Morphologic appearance of postmortem changes
What is Rigor mortis?
Contraction of muscles after death
Morphologic appearance of postmortem changes
What is Livor mortis?
Gravitational pooling of blood
In large vessels, clotting happens then the separation of blood cells & plasma (Chicken fat)
Morphologic appearance of postmortem changes
What is Postmortem clotting?
Botton RBC, Top plasma
( Chicken fat )
Morphologic appearance of postmortem changes
What is hemoglobin inbibition?
Red staining of tissue
Especially heart and vessels ( apparent in Aorta )
Morphologic appearance of postmortem changes
What is bile imbibition?
Staining of tissue around gallbladder after bile penetrates its wall
Morphologic appearance of postmortem changes
What is pseudomelanosis?
Bluegreen discoloration of tissue by FeS
H2S by putrefactive bacteria + Fe2+ from RBC
Morphologic appearance of postmortem changes
What is bloating?
Postmortem bacterial metabolism that causes gas formation in lumen ( Ruminants forestomach and equine cecum )
Morphologic appearance of postmortem changes
What is Pale foci subserosally?
Paler organ caused by
- Increased intraabdominal pressure -> Squeeze blood away
- Bacterial infection -> Looks like coagulative necrosis
Morphologic appearance of postmortem changes
What is mucosal sloughing?
Rapid shedding of mucosa in rumen by enzymes
Morphologic appearance of postmortem changes
What is lens opacity?
Turbidity of lens caused by the extreme coldness
Back to transparent when warm
Often confused with cataracts
What causes Rigor mortis?
Calcium influx into muscle cell causes contraction
