Download Cell Death - Metabolism

Cell Death
Hoon Lee
Cell Death
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Within each cell line, the control of cell number
is regulated by a balance of cell proliferation
and cell death.
There are two principle patterns of cell death
1. Necrosis (death by injury)
2. Apoptosis (death by suicide)
Necrosis
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Refer to cell death in an organ or tissue.
Caused by infarction, infectious disease,
poisoning etc.
Affects contiguous groups of cell.
Usually precipitates an inflammatory response.
Cytological characteristics of
Necrosis

Initial swelling of the cell.

Rupture of the plasma
membrane.

Cytoplasm is spilled to
the extracellular
environment.
Types of Necrosis

Coagulation Necrosis (seen in infarcted organs,
e.g.myocardial infarct).

Liquefaction Necrosis (softening of the center of an
abscess)

Caseous Necrosis (cheesy, crumbly appearance, e.g.
Tuberculosis lesion in the lung)
Apoptosis

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Responsible for Programmed Cell Death
(PCD)
Plays an important role in multicellular
development.
Cause deletion of individual cells in the midst
of others.
No inflammatory response but rapid
phagocytosis
Cytological characteristics of
Apoptosis
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Nucleus condensation.
Membranes preserved.
Fragmentation.
phagocytosis
Examples of Programmed Cell
Death
Phylogenic: the loss of the vertebrate tail during human
fetal development.
 Morphogenic: the loss of mesenchyme between the
digit.
 Histogenic: the reduction of numbers of neurons in the
developing brain.
*(PCD occurs during embryonic development as mitosis)
 Normal maintenance.
 Suicide cell death: virtually infected cells.

Mechanism of Apoptosis

Internal signals: Mitochondrial pathway.

External signals: Death receptor pathway.

Apoptosis-Inducing Factor.
Internal signals: Mitochondrial
pathway
External signals: Death receptor
pathway
Apoptosis-Inducing Factor (AIF)
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Release from the mitochondria.
Migrates into the nucleus.
Bind to DNA.
Destruction of the DNA
Cell death.