is Apoptosis genetically programmed cell death.
(a'pohtoh'sis, from the Greek for "dropping off", as in petals falling from a flower)
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Characteristics of Death by Apoptosis
The cells shrink. Their mitochondria break down with the release of cytochrome c. They develop "blebs" on their surface. Their chromatin is degraded. They are degraded into small membranewrapped, fragments which are usually engulfed by nearby macrophages. This process does not induce inflammation.
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Why do cells kill themselves?
Programmed cell death is needed for proper development.
Programmed cell death is needed to destroy cells that represent a threat to the integrity of the organism.
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Immune System Memory Cells Normally lymphocytes (B cells and T cells) last for only several weeks before their apoptosis mechanisms are activated. However, when lymphocytes contact a complementary foreign antigen, growth hormones are released by the target cells which turn off the apoptosis death program, extending the life of the cells from weeks to years. These lymphocytes act as "memory" cells that able are to recall the prior contact with the molecules of pathogens.
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Death Activators
TNF Lymphotoxin Fas ligand (FasL)
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Caspase the executioner
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Defects in the apoptotic machinery is associated with autoimmune diseases.
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Function of Cytokines: Development of cellular and humoral immune responses Induction of inflammation Regulation of hematopoiesis Control of cellular proliferation and differentiation Induction of wound healing
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Neural Pathways About 50% of the neurons present at birth die after synapses form. How does this happen?...