Pathology Flashcards
(251 cards)
Pneumatosis intestinalis
gas cysts in the intestine wall
Toxic epidermal necrolysis
♣ Code: walls covered in rotting skin oozing green and grim reapers/toxic epidermal necrolysis. John, Canadian immunology professor/usually older. Skin looks like belwo/more severe version of Steven-Johnson syndrome. Russians drinking vodko/presentation = diffuse erythema + blistering with a positive Nikolsky sign. Lips completely necrotic and blistering/usually presents with involvement of mucous membranes. Pile of piles behind him/usually triggered by use of a new medication.
♣ Character: Room inside of SJS room
caspases
cytosolic proteases involved in apoptosis
apoptosis characteristics
- cell shrinkage + chromatin condensation + membrane blebbing + formation of apoptotic bodies, which are then phagocytosed.
- deeply eosinophilic cytoplasm + basophilic nucleus + pyknosis + karyorrhexis.
pyknosis
nuclear shrinkage
karyorrhexis
fragmentation of the nucleus caused by endonucleases cleaving at internucleosomal regions.
Indicator of apoptosis
DNA laddering
DNA laddering
(fragments in multiples of 180 bp)
differentiating feature from apoptosis and necrosis
cell membrane remains intact without significant inflammation
Pathway involved in tissue remodeling in embryogenesis
intrinsic (mitochondrial) pathway.
When does intrinsic pathway occur?
1) regulating factor is withdrawn from a proliferating cell population (decreased IL-2 after a completed immunologic regulation leading to apoptosis of proliferating effector cells).
2) after exposure to injurious stimuli (radiation, toxins, hypoxia).
Intrinsic pathway regulation and examples
Bcl-2 family of proteins, such as BAX and BAK (proapoptic) and Bcl-2 (antiapoptotic)
Bcl-2 action
Prevents cytochrome c release by binding to and inhibiting APAF-1.
APAF-1 action
APAF-1 binds cytochrome c and induces activation of caspase 9, initiating caspase casade.
What happens with Bcl-2 over expression?
decreased caspase activation and tumorigenesis.
extrinsic (death receptor) pathway
2 pathways:
1) ligand receptor interactions (FasL binding to Fas [CD95] or TNF-alpha binding to TNF)
2) Immune cell (cytotoxic T-cell release of perforin and granzyme B)
When is Fas-FasL interaction necessary? What happens with mutations?
Thymic medullary negative selection. Mutations in Fas increase numbers of circulating self-reacting lymphocytes due to failure of clonal deletion.
What happens with defective Fas-FasL interactions?
Autoimmune lymphoproliferative syndrome.
Intrinsic pathway with DNA damage/radiation/misfolded proteins/hypoxia etc.
DNA damage –> p53 activation –> BAX/BAK activation –> cytochrome C release –> initiator caspases –> executioner caspases
necrosis
Enzymatic degradation and protein denaturation of cell due to exogenous injury leading to intracellular components leak. *inflammatory process.
coagulative necrosis cause and location
ischemia/infarcts. Most tissues except brain.
What happens with coagulative necrosis
proteins denature. enzymes are degraded. cell outlines preserved. increased cytoplasmic binding of acidophilic dyes.
when does liquefactive necrosis occur?
bacterial abscesses + brain infarcts (due to icnreased fat content)
liquefactive necrosis pathophys
Neutrophils release lysosomal enzymes that digest the tissue; enzymatic degradation first, then proteins denature.