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Flashcards in Apoptosis And Necrosis Deck (29):
1

Apoptosis

Programmed cell death

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Necrosis

A series of morphological changes during cell death after lethal damage
-staged cell death due to unintended damage

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Physiological apoptosis

1. During embryonic development
2. During immune system development

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Pathological apoptosis

1. Triggered by immune system cells in response to cell infection
2. Self induced due to defective function, developing cytotoxicity

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Can necrosis be physiological and pathological?

No, it's always pathological

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Necrosis involves

-disruption of the metabolic process
-cellular component desaturation
-loss of membrane integrity and release of cellular components to surroundings

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Apoptosis during embryonic development

Phylogenic organism development programs use programmed cell death as a means of removing unwanted cells: tissue between fingers and toes

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Apoptosis during immune system development

-T cells are tested against 'self antigens' and if they recognize and bind self antigens, they undergo apoptosis to remove their own lineage
-if they did not 'self-destruct' they would kill normal cells upon activation leading to autoimmune disorders

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Apoptosis triggered by immune system cells

When a harmful/compromised cell is identified, innate immune cells trigger that cell's apoptosis program

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After the cells innate immune cells trigger apoptosis what happens

-infected cells display 'non-self antigens'
-transformed 'cancer' cells display unusual attributes
-damaged cells or cells developing characteristics of damage

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Self induced apoptosis

-cells that surpass specific thresholds acceptable for survival can self induce apoptotic programming. This may include slight metabolic defects or the accumulation of toxic substances such as aggregating proteins

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Intrinsic apoptotic pathways

Initiated by interior signaling die to irreparable, irreversible DNA damage

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What can cause a cell to undergo intrinsic apoptotic pathway?

-severe stress
-pro-apoptotic proteins from the nucleolus and mitochondria activate the CASPASE CASCADE
-caspases destroy proteins and other molecules with in the cell
-cell begins to bleb into vesicles
-phagocytes cells engulf and digest the 'blebbed' vesicles

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Extrinsic apoptotic pathway

Initiated by exterior signals due to indications of damage or infection

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What could cause extrinsic apoptotic pathway?

-T cell or TNFa induced activation of death domain proteins
-activation of capsase cascade
-capsases destroy proteins and other molecules with in the cell
-cell begins to bleb into vesicles
-phagocytes cells engulf and digest the 'blebbed' vesicle

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AIF-apoptosis inducing factor

A capsase independent form of apoptosis

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What is AIF initiated by?

Damage to the mitochondrion and release of material from the mitochondrial inner membrane space to the cytosol

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AIF leaving the mitochondrial

Passes through the cytosol to the nucleus where it causes chromosome condensation

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What happens once the chromosomes are condensed in AIF?

The DNA is chopped up

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The over all effect of AIF

Results in the compete depletion of energy stores in the cell, no production of new proteins or metabolites, cell 'blebbing', and a quiescent cell death similar to apoptosis utilizing caspases

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What is the difference between intrinsic/extrinsic and AIF

Extrinsic and intrinsic involve capsases

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Which forms of apoptosis is considered quiescent?

All of them

23

What could be some unintended damage that would cause staged cell death (necrosis)?

-trauma
-infection
-radiation
-toxins
-ischemia
-heat/cold

Usually environmental in nature

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What does necrosis involve?

-disruption of the metabolic process
-cellular component denaturation
-loss of membrane integrity and release of cellular components

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Disruption of the metabolic process in necrosis

-Loss of TCA and ETS
-glycolysis drives formation of lactic acid.
-rely totally on glycolysis, build up of lactic acid

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Cellular component denaturation in necrosis

Increasing lactic acid drives pH down denaturing proteins

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Loss of membrane integrity and release of cellular components In necrosis

-complete loss of all cellular function results in the release of many cellular components that will cause problems in cells/tissues surrounding it

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Overview of apoptosis

Form of cell death that is regulated and results in the formation of 'blebbed' vesicles containing the partially digested contents of the cell. This is considered a quiescent death and does not negatively impact the surrounding cells

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Necrosis overview

Results in the complete breakdown of cellular organization. Lysosomal enzymes are released to conduct autolysis and heterolysis when the cell ruptures. Enzymes and materials released cause damage to surrounding interstitial and cells, perpetuating the damage. Opportunistic microbes may benefit. Inflammatory response occurs
-after extensive clean up, tissue repair and scar tissue forming fibroblasts must be activated