Cellular Adaptation 2
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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
What are the mechanisms of hyperplasia?
What can stop hyperplasia?
- Increased DNA synthesis
- Growth inhibitors will halt hyperplasia after sufficient growth has occurred
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
What is steatosis?
- Accumulation of fat in tissue
- Due to:
- - Alcohol
- - Toxins
- - protein malnutrition
- - Diabetes Mellitus
- - Obesity
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
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
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
, but not dead
What is Metaplasia?
Reversible change in which one adult cell type is replaced by another adult cell type.
What is Barretts esophagus?
Condition of metaplasia in which esophageal stratified squamous epithelium cells change to mature columnar cells. Which may predispose to cancer
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.
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
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
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
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
What is Caseous necrosis and example?
- This type of infection involves cheesy white appearance of necrosis in TB granulomata
- Encountered most often in tuberculosis
A kidney infarct exhibiting preservation of basic outlines of architecture is exhibiting what type of necrosis
What type of necrosis involves loss of architecture of the cell, abcess presence of white cells and cellular debris?
What type of necrosis is found in the brain?
Liquifactive NOT coagulative
Macrophages liquefy and remove the necrotic tissue, living fluid filled cavity
What is typically found in cells afflicted by Tuberculosis?
- Loss of tissue architecture-amorphous granular debris
- At edge, granulomatous inflammation
- Multinucleated Langhans giant cells
Characteristics of fatty necrosis? Another term?
- Chalky white appearance
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
What are examples of decreased apoptosis?
- Autoimmune disorders
What is a common mechanism that leads to deranged apoptosis?
- Dysfunction of p53 pathways
- p53 mutations are found in 50% of malignant tumors
What is a subcellular response to cell injury?
- Lysosomal catabolism-
- -contain hydrolytic enzymes
- -degrades extracellular and intracellular materials
What is the difference between
Heterophagy- materials from external environment engulfed and destroyed
Autophagy-intracellular organelles whch have been damaged are degraded by lysosomes
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