Pathology Flashcards
Is apoptosis an inflammatory process?
No
Does apoptosis require ATP?
Yes
What are the cell changes associated with apoptosis?
- Eosinophilic cytoplasm
- Cell shrinkage
- Pyknosis (nuclear shrinkage) + nuclear basophilia
- Membrane blebbing
- Karyorrhexis (nuclear fragmentation)
- Formation of apoptotic bodies
- Phagocytosis
- memory: Think of someone that is having a breakdown. 1. First they turn red (eosinophilic cytoplasm)
2. then they clench up (cell shrinkage)
3. then their intestines clench up (nuclear shrinkage)
4. then they lash out and punch you (membrane bleb)
5. then their heart breaks (karryorrhexis)
6. then they melt into pieces (apoptotic bodies)
7. then you give them a hug (phagocytosis)
What is a sensitive indicator of apoptosis? Which phenomenon of apoptosis does this capitalize on?
DNA laddering showing multiples of 180 bp
Capitalizes on KARYORRHEXIS (nuclear fragmentation), when endonucleases cleave at internucleosomal regions, yielding multiples of 180 bp
By what mechanism does radiation therapy induce apoptosis?
- Free radical formation (–> Lipid peroxidation, protein modification, DNA breakage)
- dsDNA breakage
What are the 2 pathways for apoptosis?
- Intrinsic pathway
- Signal is generated (ex: drop in IL-2, detection of DNA damage)
- Bcl-2 is blocked
- so BAX, BAK , and Apaf-1 become uninhibited
- so mitochondrial permeability increases
- cytochrome C is released from inside mitochondria
- cytosolic caspases are activated
- Extrinsic pathway
- FasL binds to FasR (CD95)
- Multiple Fas molecules coalesce
- A binding site for FADD is made
- FADD activates cytosolic caspases
OR - Killer T cells release granzyme B and perforin
- these activate cytosolic capsases
What kind of cell death utilizes the instrinsic pathway? The extrinsic pathway?
Intrinsic:
- Embryology
- Loss of IL-2 after immune reaction completed
- Radiation
- Toxins
- Hypoxia
*memory: BIE-BIE (Bad things, IL-2 loss, Embryology)
Extrinsic:
- Killer T cells (release perforin and granzyme B)
- Thymic medullary negative selection (Fas-FasL)
Autoimmune disorders can be caused by what error in the apoptosis pathway?
Mutation in Fas or defective Fas-FasL interactions This results in more self-reacting lymphocytes in the body, which can cause autoimmune disease
Is necrosis an inflammatory process?
yes, always!
What happens first in coagulative necrosis?
proteins denature…. THEN enzymes degrade
*memory: The proteins die and coagulate, so the cells are able to maintain their shape
What happens first in liquefactive necrosis?
enzymes digest tissue (from neutrophils)…. THEN proteins denature
*memory: If the enzymes get there first, everything will be chewed up
What kind of necrosis is seen in brain infarcts? Why?
What else exhibits this type of necrosis?
Liquefactive necrosis. Because of the high fat content, AND because microglial cells contain hydrolytic enzymes
Also seen in bacterial abscesses, because neutrophils have hydrolytic enzymes
What 3 kind of processes cause caseous necrosis?
- TB
- systemic fungy (ex: Histoplasma capsulatum)
- Nocardia
What does fat necrosis look like on H&E stain? What 2 situations is this seen in?
Looks like: Dark blue (calcium stains dark blue, sign of fat saponification)
- Acute pancreatitis, 2. Breast trauma
What is the pathogenesis of fibrinoid necrosis?
Immune rxn in the vessels:Immune complexes + Fibrin = Vessel wall damage, pink
In which type of necoriss do you see lymphocytes?
Caseous necrosis (TB, nocardia, systmeic fungi). Lymphocytes and macrophages surround the fragments cells and debris.
What is the difference between dry and wet gangernous necrosis on histology?
Dry = Coagulative necrosis, Wet = Liquefactive necrosis
*memory: Dry sky means no clouds (Dry, iSKemia, CCCoag)
Pathogenesis of follicular (and undifferentiated) lymphoma
Overexpression of BCL-2 —> overinhibition of Apaf-1 –> no cell death
*memory: BCL-2 takes care of YOU (its anti-apoptotic)
T cells undergo positive and negative selection in the thymus, and then go chill in the lymph nodes. In what part of the thymus does negative selection occur?
Negative selection: Medulla
*You can remember this because they do positive selection first in the cortex (must recognize self), and then move deeper into the medulla to do negative selection
How do overly self-reactive T cells get eliminated in the body?
Does the T cell get FasR or FasL stimulated?
T cells bind to self MHC but receive so co-stimulatory signal (B7 on a dendrite or CD40 on a B cell), so the Fas-FasL pathway is initiated
I guess the Fas-R (CD95) on the T cell is stimulated
What early changes are seen histologically in brain infarcts? Late changes?
Early: Cellular debris, macrophages
Late: Cystic spaces, cavitation
Diabetics with atherosclerosis in the popliteal artery are particularly susceptible to what kind of necrosis?
Gangraneous (this type of necrosis is typical for any kind of chronic ischemia in the distal extremity. If a superimposed infection occurs, it will become wet/liquefactive. If not, it will be dry/coagulative).
What is the hallmark of reversible cell injury (reversible with oxygen)?
Cellular swelling
What is the hallmark of irreversible cell injury?
Plasma membrane damage
and therefore leakage of troponin, amylase, etc
Reversible or not: Decreased glycogen
Yes
Think of the glycogen just being diluted out by water
Reversible or not: Fatty change
Yes
Side Note: CCl4 induces free radical injury and first causes cellular swelling and then fatty change/liver necrosis. –> apolipoproteins lacking because ribosomes popped off RER
Reversible or not: Mitochondrial swelling
Yes
Reversible or not: Mitochondrial vacuolization
No! This means mitochondrial permeability. Phospholipid amorphous densities accumulate within the mitochondria.
Reversible or not: Lysosomal rupture
No! Anything with a messed up membrane will be irreversible
Reversible or not: Membrane blebbing
Yes!
If it is associated w/ cells turning pink, shrinking, and nucleus shrinking or breaking then NO! This would go along with apoptosis
But if it is associated with just cell swelling, then YES
Reversible or not: Nuclear chromatin clumping
Yes (this is the only nuclear change that is allowed)
Reversible or not: ATP depletion
Yes!