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What are causes of pathological hyperplasia?
- Excess growth factors or hormones, ie endometrial hyperplasia (hormone sensitive cancer)
- Viral infections, such as papillomavirus
- Note-pathologic hyperplasia may become malignant cancer
- Hyperplasia can effect either a mature cell or Stem Cells
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What are the mechanisms of hyperplasia?
What can stop hyperplasia?
- Increased DNA synthesis
- Growth inhibitors will halt hyperplasia after sufficient growth has occurred
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Result of chronic hypertrophy?
Risks of hypertrophied tissue?
- Organ of hypertrophied tissue will most likely proceed to failure.
- Hypertrophied tissue is at increased risk for ischemia
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What is steatosis?
Causes?
- Accumulation of fat in tissue
- Due to:
- - Alcohol
- - Toxins
- - protein malnutrition
- - Diabetes Mellitus
- - Obesity
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What are the mechanisms of atrophy?
What is the name of the pathway involved with atrophy?
- Decreased protein synthesis
- Increased protein degradation via the Ubiquitin Proteosome Pathway
- Accompanied by autophagy, "self-eating" due to starved cell attempting to survive
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What are causes of atrophy?
- Decreased workload (disuse) such as muscle in cast.
- Loss of innervation.
- Diminished blood supply
- Inadequate nutrition.
- Loss of endocrine stimulation.
- Tissue compression for any length of time
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Summary of atrophy? What is actually happening in the cell?
- Reduced number of
- -mitochondria, source of energy
- -myofilaments, gives cell it's shape
- -Endoplasmic reticulum, where protein made
Diminished FUNCTION, but not dead
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What is Metaplasia?
Reversible change in which one adult cell type is replaced by another adult cell type.
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What is Barretts esophagus?
Condition of metaplasia in which esophageal stratified squamous epithelium cells change to mature columnar cells. Which may predispose to cancer
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What happens to the respiratory tract epithelium cells of smokers?
- Change from columnar to squamous because squamous cells more "hardy" and able to survive harsh environments.
- However, the cells ability to secrete mucous is lost.
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What is one important factor that determines whether cell tissue has reversible or irreversible injury?
- Time of loss of blood flow to tissue.
- Myocardial tissue, only reversible injury after 10 minute time lapse of blood flow interruption; however, irreversible injury after 1 hour lapse of blood flow to myocardial tissue
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What is coagulative necrosis and what is an example where it can be found?
- Architecture of tissue is preserved. The basic cell outline is intact. Proteolysis of dead cells is blocked because injury of cell denatures enzymes involved.
- Ex. is ischemia caused by obstruction in a vessel may led to coagulative necrosis in all organs except the brain.
- Common in kidneys
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What is liquefactive necrosis and example?
- This type is characterized by digestion of the dead cells resulting in transformation of the tissue into a liquid viscous mass
- Necrotic material is frequently creamy yellow bc presence of dead neutrophils
- Common in:
- - brain abcess
- - Hypoxic death of cells within the central nervous system
- - Or infection->leukocytes excrete enzymes
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What is Gangrenous necrosis?
How is this term usually applied?
What is "Wet gangrene?"
- Not a specific pattern of cell death.
- Usually applied to a limb, generally lower leg, that has lost blood supply, undergone typically coagulative necrosis
- Wet gangrene is when it's also associated with bacterial infection
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What is Caseous necrosis and example?
- This type of infection involves cheesy white appearance of necrosis in TB granulomata
- Encountered most often in tuberculosis
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A kidney infarct exhibiting preservation of basic outlines of architecture is exhibiting what type of necrosis
Coagulative
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What type of necrosis involves loss of architecture of the cell, abcess presence of white cells and cellular debris?
Liquefactive necrosis
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What type of necrosis is found in the brain?
Liquifactive NOT coagulative
Macrophages liquefy and remove the necrotic tissue, living fluid filled cavity
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What is typically found in cells afflicted by Tuberculosis?
- Loss of tissue architecture-amorphous granular debris
- At edge, granulomatous inflammation
- Multinucleated Langhans giant cells
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Characteristics of fatty necrosis? Another term?
- Chalky white appearance
- Saponification
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What are some examples of pathological apoptosis?
- Certain types of cell injury/DNA damage, radiation, chemotherapy, drugs
- Viral infections (AIDS)
- Tumors that regress or involutions
- Rejection of transplants (graft rejection)
- Neurodegenerative disorders
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What are examples of decreased apoptosis?
- Tumors
- Neoplasia
- Autoimmune disorders
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What is a common mechanism that leads to deranged apoptosis?
- Dysfunction of p53 pathways
- p53 mutations are found in 50% of malignant tumors
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What is a subcellular response to cell injury?
- Lysosomal catabolism-
- -contain hydrolytic enzymes
- -degrades extracellular and intracellular materials
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What is the difference between
Heterophagy
Autophagy
Heterophagy- materials from external environment engulfed and destroyed
Autophagy-intracellular organelles whch have been damaged are degraded by lysosomes
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