apoptosis & necrosis Flashcards
what are apoptosis & necross
two processes that result in cell death
VERY DIFFERENT
define apoptosis
programmed cell death
why does apoptosis occur
important process for normal cell turnover to prevent cells with accumulated genetic damage from dividing and producing cells which might eventually develop into cancer cells
how does a cell decide to apoptose
amount of DNA damage within the cell
p53 protein detects DNA damage and can trigger apoptosis
types of DNA damage
Single-strand break
Base alteration
Cross-linkage
how does a cell apoptose
the cell triggers a series of proteins which lead to the release of enzymes within the cell which eventually autodigest the cell
= cascade of activated enzymes
what is apoptosis important for in the body
development and cell turnover
why is apoptosis important fot development
removal of cells during development
why is apoptosis important for cell turnover
removal of cells during normal turnover
which diseases is apoptosis in
cancer and HIV
how is apoptosis used in cancer
cells in tumours often dont apoptose when they would have been expected - causes increases in tumour size and accumulation of genetic mutations
often due to mutations in p53 so it cant detect DNA damage and start apoptosis
how is apoptosis used in HIV
HIV virus can induce apoptosis in CD4 helper cells which reduces their numbers to produce an immunodeficient state
define necrosis
death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply
DUE TO EXTERNAL FACTOR
clinical examples of necrosis
Toxic spider venom
Frostbite
Cerebral infarction
Avascular necrosis of bone – femur has single arterial supply through the neck of the femoral head
Pancreatitis
what does the body do after necrosis
clear up the mess by macrphages phagocytosing dead cells and replacing necrotic tissue by fibrous scar tissue
