Cell Death And Cell Damage Flashcards
What is the purpose of necrosis?
Removes damaged cells from an organism
Why does necrosis cause acute inflammation?
Clear cell debris via phagocytosis
What are the causes of necrosis?
Lack of blood supply as a result of: Injury Infection Cancer Infarction Inflammation
What is the step by step of necrosis?
injurious agent or event
- > lack of oxygen prevents ATP production
- > cells swell due to influx of water
- > lysosomes rupture: enzymes degrade other organelles and nuclear material haphazardly
- > cellular debris is released, triggering inflammation
What are the three changes in the microscopic appearance of necrosis?
Nuclear, cytoplasmic and biochemical
What are the nuclear changes that happen in necrosis?
Chromatin condensation
Fragmentation of the nucleus
Dissolution of the chromatin by DNAase
What are the cytoplasmic changes that happen in necrosis?
Opacification: protein denaturation and aggregation
Complete digestion of cells by enzymes causing cells to liquefy
What are the biochemical changes that happen in necrosis?
Release of enzymes such as creatinine kinase or lactate dehydrogenase and other proteins like myoglobin
Why are biochemical changes useful in a clinical setting?
Measure the extent of tissue damage
What are the functions of apoptosis?
Deletion of superfluous, injected or transformed cells
What is apoptosis involved in?
Embryogenesis Metamorphosis Normal tissue turnover Endocrine-dependent tissue atrophy Variety of pathological conditions
What is the step by step of apoptosis?
Programmed cell death of one or a few cells
- > cells shrink as the cytoskeleton is disassembled
- > orderly packaging of organelles and nucelar fragments into membrane bound vesicles
- > new molecules are expressed on vesicular membranes that stimulate phagocytosis without an inflammatory response
Is necrosis reversible?
Initial events are reversible, later ones are not
Is apoptosis reversible?
No
What are the cytoplasmic changes in apoptosis?
Shrinkage of cell
organelles packaged into membrane vesicle
Phagocytosis of cell fragments by macrophages and adjacent cells
No leakage of cytosolic components
What are the nuclear changes in apoptosis?
Nuclear chromatin condenses on nuclear membranes
DNA cleavage
What are the biochemical changes in apoptosis?
Expression of charged sugar molecules on the outer surface of cell membranes
Protein cleavage by proteases
What are the two types of apoptosis?
Intrinsic and extrinsic
What causes intrinsic apoptosis (specifically)?
DNA damage interruption of the cell cycle Inhibition of protein synthesis Viral infection Change in redox state
What causes extrinsic apoptosis?
Survival factors
Extracellular signals
Tcell or natural killer