Cell death Flashcards
Describe the adaptive cellular responses
- Failure to adapt- failure of cellular function leads to..
- > Sublethal cell injury- cell endures stimulus but doesn’t die
- > Cell death
What is apoptosis?
Programmed cell death
What is oncosis?
Cell death due to pathological reasons
What is coagulative necrosis?
Severe ischaemia in solid organs
What is liquefactive necrosis?
Hydrolytic enzyme release in the brain
What is caseous necrosis?
Cheese-like, seen in TB
What is fat necrosis?
Typical in breast and pancreas
What is fibrinoid necrosis?
Damaged arteries (e.g. vasculitis)
What is haemorrhagic necrosis?
Dead tissue packed with extravasted RBC, blocked benous drainage–> congestion and arterial perfusion failure
What is a gangrene?
- Dead black tissue
- Dry: coagulative type necrosis
- Wet: tissue infected with gram negative bacteria
Describe apoptosis
- Cytoplasmic contents not released
- Cell components may be recycled
- Controlled genetically and apoptotic blebs phagocytosed
- Embryonic development, homeostatic mechanism to maintain cell populations, defence mechanism, cell damage/ageing
Describe the mechanisms of apoptosis
- Lack of growth factors/hormones
- Ligand-receptor interaction
- Injurious agents, DNA
- Tc and NK cells
What are the stages of apoptosis?
- Initiation: stimulated by Bax protein and pores form in mitochondrial membrane
- Execution: activation of interior and executor capsases–> endonuclease activation, breakdown of cytoskeleton and apoptotic body formation
- Disposal: phagocytosis by macrophages/ adjacent endothelial cells
Compare oncosis and apoptosis (oncosis)
- Contiguous and pasive
- Cells swell- water influx
- Enzymes destroy organelles
- Stimulates inflammation
- PATHOLOGICAL
Compare oncosis and apoptosis (apoptosis)
- Single/few cells and active
- Disassembled cytoskeleton
- Vesicles- phagocytosed- ordered packaging
- Physiological or Pathological
Describe hypoxia
- Obstruction of blood flow- lack of oxygen- less oxidative phosphorylation- less ATP- membrane damage and rupture of lysosomes and ER
How do microorganisms cause cell damage?
- Toxins affecting metabolism/enzymes breakdown tissue
- Inflammatory/immune response or intracellular replication
Describe drugs and toxins
- Non-specific chemical reactions with cell molecules
- Specific biochemical/physiological effects
- Inflammation/immune reactions or reactions with DNA
Describe autolysis
- Cell death- digestive intracellular enzymes (lysosomes)
- Occurs after death of organism or removal from organism
What type of bacteria causes caseous necrosis?
- Mycobacteria
What is an infarction?
Necrosis due to ischaemia
What chemical is used to preserve samples and prevent apoptosis?
Formaldehyde
