Exam 2 Flashcards
Define acute cell swelling
Early, sub-lethal manifestation of cell damage, characterized by increase cell size and volume due to water overload.
Etiology of acute cell swelling
-Loss of ionic and fluid homeostasis -Failure of cell energy production -Cell membrane damage -Injury to enzymes regulating ion channels of membranes
Describe the gross appearance of acute cell swelling
-Slightly swollen organ with round edges -Pallor when compared to normal -Cut surface: tissue bulges and cannot be easily put in correct apposition
What is this image showing ?
Cellular swelling
- Water uptake dilutes the cytoplasm
- Cells are enlarged with pale cytoplasm
- May show increased cytoplasmic eosinophilia
- Nucleus in normal position, with no morphological changes
Etiology of the image?
Swinepox virus
What are the ultrastructural changes of cellular swelling
- Plasma membrane alterations: blebbing, blunting, and loss of microvilli
- Mitochondrial changes: including swelling and the appearance of small amorphous densities
- Dilation of ER: with detachment of polysomes, intracytoplasmic myelin figures may be present
- Nuclear alterations: with disaggregation of granular and fibtillary elements
Define Fatty change
- sub-lethal cell damage characterized by intracytoplasmic fatty vacuolation
- May be preceded or accompanied by cell swelling
What is lipidosis
- accumultation of triglycerides and other lipid metabolites within parenchymal cells
- Heart muscle, skeletal muscle, kidney, liver
What is the etiology of fatty change
Main causes: hypoxia, toxicity, metabolic disorders
-Seen in abnormalities of synthesis, utilization and/or mobilization of fat
Pathogenesis of fatty liver
- Excessive delivery of FFA from fat stores or diet.
- Decreased oxidation or use of FFAs
- Impaired synthesis of apoprotein
- Impaired combination of protein and triglycerides to form lipoproteins
- Impaired release of lipoproteins from hepatocytes
Describe the gross appearance of fatty change
- Liver: diffuse yellow (if cells are affected)
- Enhanced reticular pattern if specific zones of hepatocytes are affected
- Edges are rounded & will bulge on section
- Tissue is soft, often friable, cuts easily and has a greasy texture
- If condition is severe small liver sections may float in fixative or water
What is the image showing? describe it
Histologic appearance of fatty change
- Well delineated, lipid-filled vacuoles in the cytoplasm
- Vacuoles are single to multiple, either small or large
- Vacuoles may displace the cell nucleus to the periphery
What is the prognosis of fatty change?
-> Initially reversible – can lead to hepatocyte death (irreversible)
Hepatic lipidosis: is seen in cats, ruminants, camelids, and miniature equines, but is rare in dogs and uncommon in other horses. It is seen more often in obese cats, secondary to anorexia of any cause. Mortality is high without treatment.
- ID and treatment of any predisposing diseases and aggressive nutritional support is required for the therapy of hepatic lipidosis.
- Oral appetite stimulants can be given but are usually inadequate alone.
Irreversible injury is associated morphologically with?
Severe swelling of mitochondria
- Extensive damage to plasma membranes (giving rise to myelin figures)
- Swelling of lysosomes
Define Necrosis (irreversible cell injury)
- Cell death after irreversible cell injury by hypoxia, ischemia, and direct cell membrane injury. (Viruses, bacterial, drugs)
- Morphologic aspect is due to 2 concurrent processes:
- Denaturation of proteins
- Enzymatic digestion of the cell
- by endogenous enzymes derived from the lysosomes of the dying cells= autolysis (self digestion)
- By release of lysosome’s content from infiltrating WBCs
What is this image showing? Describe it
Pale, soft, friable, and sharply demarcated from viable tissue by a zone of inflammation
**Don’t think black**
TURKEY
- MDx: Hepatitis, multifocal to coalescing, subacute, severe, necrotizing
- Et: Histomonas Meleagridis (heterakis causes black head)
- Name = Blackhead
What is the cause of necrotic cells in cytoplasm
Denatured proteins: Loss of RNA, Loss of glycogen particles, enzyme-digested cytoplasm organelles.
What is the image showing? Describe the appearance
The image is showing changes of necrotic cells in cytoplasm
Appearance:
- Increase binding of eosin (pink), loosing basophilia, glassy homogeneous, vacuolation and moth eaten appearance, calcification may be seen.
What is a common example of coagulation necrosis
infarct
What is the image showing? and what is a common cause?
Infarct: localized area of coagulative necrosis
Common cause: Ischemia in all solid organs except the brain
Label 1-4
- Normal tissue
- Congestion and hemorrhage
- Leukocyte barrier
- Coagulation necrosis
Liquefactive necrosis occurs in:
- Tissue with high neutrophil recruitment and enzymatic release with digestion of tissue
- Tissues with HIGH LIPID CONTENT
- Focal bacteria and occasionally, fungal infections
- Microbes stimulate the accumulation of WBCs and the liberation of enzymes from these cells
What is the image showing ?
Liquefactive necrosis - gross
Sheep, brain stem
MDx: Bilateral symmetrical encephalomalacia
What is this image showing?
Pathogenesis?
Species affected?
Leukoencephalomalacia = necrosis of the white mater of the brain
Pathogenesis: ingestion of Fusarium moniliforme containing Fumonisin B1 toxin-producing moldy corn > sphingolipid synthesis inhibition > direct cellular toxicity > leukoencephalomalacia
Species affected: Horse, chicken, pig
What is the image showing? Species?
DDx?
Horse: multifocal hemorrhagic Polyomyelitis
DDx: Equine herpes vrius 1, Rabies (lyssavirus), West Nile Virus (flavivirus)
What is the image showing?
Brain, Polioencephalomalacia
What is the image showing? Species?
Gross Liquefactive necrosis
Goat: Pituitary gland abscess
Necrotic material is frequently creamy yellow because of the presence of dead WBC = PUS
Define what an Abscess is
A localized collection of pus (liqueified tissue) in a cavity formed by disintegration of tissues surrounded by fibrous CT (not in CNS)
**No CT in the Nervous System**
What are the two types of abscesses
- Septic: the majority = infection, release of enzymes from WBCs and infectious agent
- Sterile: process caused by nonliving irritants such as drugs- likely to turn into firm, solid lumps as they scar, rather than remaining pockets of pus
What is the following image?
Histology of liquefactive necrosis - eg. Abscess
- Loss of cellular detail = main characteristic
What is the following image showing?
Gangrenous Necrosis
What is the difference between “Dry” and “Wet” Gangrene
- “Dry” Gangrene no bacterial superinfection; tissue appears dry
- “Wet” Gangrene- bacterial superinfection has occurred; tissue looks wet and liquefactive
What is Caseous necrosis
“Caseous”= cheeselike
-Friable (crumble) white; area of necrosis
Necrotic debris represents dead WBCs
What are the possible causes of Caseous necrosis
- Mycobacterium
- Corynabacterium
- Fusobacterium
- Fungal infections
What is the following image?
Corynebacterium pseudotuberculosis
Disease name: Caseous lymphadenitis
What is the following image? Species?
MDx and name of disease
Cow
MDx: Multifocal caseous pneumonia
Name of disease: Tuberculosis
What is caseous necrosis often associated with?
Poorly degradeable lipids of bacterial origin
What is the following image showing?
Histopathology -> necrotic area -> eosinophilic granular cell debris with a rim of inflammatory cells
- Obliterated tissue architecture
- Dystrophic calcification (commonly to occur in center of lesion)
What are the three types of Fat Necrosis
- Enzymatic necrosis
- Traumatic Necrosis of fat
- Necrosis of abdominal fat
What is the following image?
Enzymatic necrosis aka pancreatic necrosis of fat
What is the following image?
Enzymatic necrosis of fat, dog with previous bouts of pancreaitis. Necrotic fat often becomes saponified, so grossly the lesion is chalky to gritty white and pale.
What is the following image?
Fat necrosis, cow, abdominal cavity
What is the following image? Explain
Fibrinoid Necrosis
- Special form of necrosis usually seen in immune reactions involving blood vessels
- Occurs when Ag-Ab complexes are deposited in the walls at arteries
- Deposits of these “immune complexes” together with fibrin that has leaked out of vessels, result in dark pink & amorphous appearance in H&E stains, called “fibrinoid” (fibrin-like) by pathologist.
Define Apoptosis
- A pathway of cell death (others include cell death with autophagy and keratinocyte cornification
- Induced by a tightly regulated suicide program
- Cells destined to die activate intrinsic enzymes that degrade the cells’ own nuclear DNA and nuclear and cytoplasmic proteins
- Apoptotic cells break up into fragments, called apoptotic bodies, which contain portions of the cytoplasm and nucleus.
Is there any inflammation in apoptosis?
- No inflammation
- It is genetically related -> sometimes referred to as programmed cell death
Describe the morphology of apoptosis
- Cell shrinkage with Increase cytoplasmic density
- Chromatin condensation (pyknosis)
- Formation of cytoplasmic blebs and apoptotic bodies (fragmentation)
- Phagocytosis of apoptotic cells by adjacent healthy cells
What are the mechanisms of apoptosis ?
Specific feature: activation of caspases (cysteine proteases family)
- Initiator caspases: 9 & 8
- Executioner caspases: 3 & 6
What pathways need to be initated for apoptosis?
- Intrinsic pathway = mitochondrial pathway
- Extrinsic pathway = death receptor-initiated pathway
How are apoptotic cells removed
- Edible for phagocytes
- Expressed phospholipids in the outer layer of the membrane (instead inner leaflet) to be ID by MQ receptors
- May become coated w/ natural Ab & proteins of the complement system (C1q)
What are some disorders associated with dysregulated apoptosis
Disorders associated with defective apoptosis and increase cell survival (abnormal cells survive)
- Cells w/ mutations in p53 are subjected to DNA damage, not only fail to die but are susceptible to the accumulation of mutations because of defective DNA repair, these can give rise to NEOPLASIA
What are some disorders assocaited with increased apoptosis and excessive cell death
1. Neurodegenerative dz: manifested by loss of specific sets of neurons (apoptosis caused by mutations and misfolded proteins)
2. Ischemic injury, as in myocardial infarction and stroke
3. Death of virus-infected cells
What is cellular injury
- Damage or pathologic alterations in molecules and/or structure that can occur in cells and extracellular components
What are the classic examples of the cause of cell injury
- Oxygen deficiency
- Infectious agents
- Immunologic dysfunction
What causes hypoxia/anoxia?
- Inadequate oxygenation of blood -> heart failure, respiratory failure
- Reduced transport of oxygen in blood -> anemia, carbon monoxide toxicosis
- Reduction in blood supply = ischemia -> thrombosis
- Blockage of cell respiratory enzymes -> cyanide toxicosis
Define hypoxia/anoxia?
Hypoxia = partial reduction to oxygen delivery to a tissue
Anoxia = no oxygen delivery to a tissue
What are the 6 major mechanisms of cell injury ?
- Depletion of ATP
- Mitochondrial damage
- Loss of Ca homeostasis
- Reactive oxygen species
- Membrane damage
- Protein misfolding, DNA Damage
True or false - ATP is required for almost all synthetic and degradative processes within the cell
TRUE
Depletion of ATP is assocaited with ?
Depletion of ATP = Fundamental cause of necrotic cell death
- Hypoxic injury
- Toxic injury -> eg. Cyanide