Integrity: Injury to Cells Flashcards
Cell injury overview cheat sheet
Key differences between cell necrosis and apoptosis
Necrosis: Uncontrolled cell death due to irreversible damage. Sweeling if mitochondria and endoplasmic reticulum. Contents are spilled attracting inflamation
Apoptosis: Controlled cell termination. Chromatin condenses in the nucleus. Small parts break off into apoptotic bodies which then undergo phagocytosis
4 triggers of apoptosis?
Intrinsic (mitochondria initiated):
- Injury - DNA damage
- Withdrawal of growth factors
Extrinsic (death receptor initiated):
- Receptor ligand interactions
- Cytotoxic T-lymphocytes (this is the FAS ligand)
Two ligand receptors for apoptosis?
FAS receptor (cytotoxic T-lymphocytes)
TNF receptor
How to the apoptotic bodies attract phagocyte?
They ligands for phagocytic cell receptors
What can the developmental consequences of failure of apoptosis be?
Failure of parts which are meant to separate e.g. webbed fingers
WHat is Autophagy?
- Indispensable, regulated, and conserved catabolic
process - Recycling and turnover of cytoplasmic cell
constituents - Response to extra- or intracellular stress (nutrient
starvation, differentiation, metabolic stress, and
developmental triggers)
5 types of necrosis
- Coagulative
- Liquefactive
- Caseous
- Gangrenous (dry)
- Fat
What is coagulative necrosis and when does it occur?
- Cell proteins denature; “ghost” outlines
- Cells lose nuclei and stain more deeply
- Occurs due to ischemia e.g. myocardial infarction
What is liquefactive necrosis and when does it occur?
- Cell proteins digested; full loss of tissue architecture
- Infiltration by inflammatory cells (neutrophils) – pus
- If there is a secondary infection by bacteria – wet gangrene
- Occurs in lipid rich tissue e.g. cerebral infarction
What is wet gangrene?
This is where liquefactive necrosis becomes infected
What is caseous necrosis and when does it occur?
- End result of
granulomatous
inflammation - Occurs in autoimmune conditions,
foreign body,
mycobacterial infection
(M.tuberculosis)
When granulomatous infection think T.B
What is dry gangrene necrosis and when does it occur?
- Coagulative necrosis of extremity due to slowly developing vascular occlusion e.g. diabetic
What is fat necrosis and when does it occur?
- Degradation of fatty tissue by lipases, forming chalky
deposits - E.g. in acute pancreatitis, trauma to fatty tissues
What is a common pathological failure of apoptosis?
Cancer - blocks apoptosis so it can survive and proliferate
What are caspases?
These are the enzymes that are activated within a cell that carry out the apoptosis
