PATH201 Final Exam 2018 (tbc) Flashcards
What are the two types of cell death?
Necrosis and Apoptosis
What is apoptosis?
Cell suicide
What is apoptosis in response to?
Physiological conditions or pathological conditions
When is physiological apoptosis used?
Physiological apoptosis is important for cell removal during embryogenesis, hormone dependent involution, cell death via immune system, and the removal of damaged cells during normal cell division.
When is pathological apoptosis used?
pathological apoptosis can occur after some forms of cell injury, in particular DNA and protein damage
What are the steps of apoptosis?
Cell shrinkage
Formation of cytoplasmic blebs
Formation of apoptotic bodies
Removal of apoptotic bodies
What happens during cell shrinkage in apoptosis?
Microvilli contraction
Breaking of intercellular junctions
Condensing of chromatin
What are the apoptotic bodies phagocytosed by?
Neighbouring cells or roving macrophages
What are the features of apoptosis?
Shrunken cell
Intact membrane
No inflammatory response
Single cell affected
Active cellular death
What is necrosis in response to?
Irreversible cellular stress
What is necrosis?
Cell homicide via enzyme digestion
How can enzyme digestion occur in necrosis?
autolysis or heterolysis
What cellular changes mark the beginning of necrosis?
Swelling
Chromatin condense
Compromised membrane
Fluid rushing in
What are the stages of necrosis?
Dissolution of cellular structures
Lysis
- Invasion of phagocytic cells
Inflammation
Why is inflammation important in necrosis?
The inflammatory response is what ultimately leads to the clearing of necrotic material and healing after necrosis.
What are the features of necrosis?
Passive cell death
Increased cell size
Disrupted membrane
Inflammatory response
Adjacent cells affected
What are the apoptotic pathways?
Extrinsic (death receptor)
Intrinsic (mitochondrial)
What allows extrinsic apoptosis to occur?
Receptor-ligand interactions
When is intrinsic apoptosis used?
In response to cell injury such as DNA damage
What is the function of cell checkpoints?
Checkpoints ensure that the cell cycle can proceed without errors.
When can DNA damage occur?
DNA damage is an error that can occur during the cell cycle which can be caused by radiation, toxins, and free radicals.
What can happen if DNA damage is unchecked?
Cell can accumulate in G1
What is activated in response to DNA damage and how?
Activation of proapoptotic proteins by BH3-only sensors
What happens in repsonse to proapoptotic protein activation?
Increase in mitochondria permeability from Bcl-2 family members (Bax and Bak)
What happens when cytochrome c enters the cytoplasm?
Caspase activation
What are caspases?
Caspases are specialised proteases that mediate both pathways of apoptosis
How are caspases activated?
Whilst inactive caspases are dimerised. This means that when cleaved, the caspases become activated