Cell Death Flashcards
(13 cards)
When does apoptosis occur
Tissue remodelling, removal of potentially harmful cells (damage found at G2 checkpoint) and removal of non-functioning immune cells
Apoptosis
Programmed cell death, tightly regulated
Necrosis
Uncontrolled cell death
Stages of apoptosis
Cells shrink and dissociate from surrounding cells, lose plasma membrane structures but organelles retain definition until late stages, membrane blebbing that’s devoid of organelles and reversible, nucleus condenses, cells split into apototic bodies = membrane bound bodies containing organelles, apoptotic bodies taken up by neighbouring cells or immune cells by phagocytosis,
Where does apoptosis occur in cell cycle
Checkpoint at S phase if DNA damaged beyond repair
Is apoptosis membrane bound
Yes, cells don’t leak their contents to surrounding tissues and there’s no damage to surrounding cells
When does necrosis occur
After injury, some causes are hypoxia and free radical damage
Stages of necrosis
Gain of cell volume, cell swelling, loss of cell membrane integrity and spillage of cellular contents, cell lysis, causes local inflammation and damage to surrounding tissues
Need for apoptosis
Eliminates potentially harmful cells and those that’ve outlived their usefulness
When does normal apoptosis occur
Embryogenesis, cytotoxic T cells clean up and cell loss in proliferating cell populations to maintain constant number of cells
Consequences of uncontrolled cell death
Change in cell death without change in proliferation leads to cancer = insufficient cell death and AIDS = excess cell death
Cancer
Uncontrolled cell proliferation, without cell death cell masses increase forming a tumour
AIDS
loss of immune cells via uncontrolled cell death so unable to fight infection
