Cell Injury And Cell Death

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..

Back 1

• Excess physiological stress
  
• Adverse pathological stimul
  

Front 2

Adaptation (4)

Back 2

Exogenous stimuli induce new state, that changes cell but preserves viabilty

Examples:

• Hyperpalsia - increase in demand
• Hypertrophy - Increase in trophic stimulation
• Atrophy - decrease in nutrients
• Metaplasia - Chronic irritation

Front 3

Reversible Injury

Back 3

Pathologic cell changes that can be restored to normal if stimuli is removed and if injury is mild

Front 4

Irreversible

Back 4

When stressors exceed capacity to adapt permanent pathologic changes cause cell death

Front 5

Causes (6)

Back 5

• Hypoxia (oxygen deprivation)
  

- Ischaemia

• Chemical agents

- Drugs, Alohol

• Physical agents

- Trauma

• Infectious agents

- Viruses

• Immunological reactions

- Reaction to infection

• Genetic derangements

- Gene mutations

• Nutritional imbalances

- Protein and vitamin deficiency

Front 6

Mechanisms of Cell Injury (5)

Back 6

Cell injury results from abnormalities in one or more offive cellular components:

• Aerobic respiration
• Cell membrane integrity
• Integrity of genetic apparatus
• Protein synthesis
• Intracellular cytoskeleton

Front 7

Cell Death

Back 7

• Necrosis:

- Always represents the pathological process

• Apoptosis:

- Represents the pathological process or severe normal physiological process

Front 8

Necrosis

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The sum of all the morphological changes that lead to cell death in living tissue/organs

- denaturation of protein

- enzymeatic digestion of cellular components and organelles

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Types of Necrosis (4)

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• Coagulative

-Most common

- Hypoxic death in all cells except brain

- Protein denaturation with preservation of cell and tissue framework

• Liquefactive
  

- Common in abscessed and brain infarcts

- Auto lysis/heterolysis predominate over protein denaturation

- Neutrophils release toxic contents "liquefy" tissue: soft and fluid filled

• Fat

- Due to trauma or release of enzymes

-

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• Caesous

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Apoptosis

Back 10

Programmed cell death occurs when a cell dies through regulated internal suicide program.

apoptosis eliminates unwanted cells selectively - minimal disturbance surrounding cells

Cell membrane remains in tact structure changes to become a target of phagocytosis

- cell shrinks and chromatin degraded, blebbing and fragmentation into apoptotic bubbles which removed by phagocytosis

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Apoptosis Causes (2)

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• Physiologic ;

- Programmed destruction during embryogenesis

-Seletion of harmful self-reactive lymphocytes

• Pathogenic

- Cell death in certain viral infections (Hep.)

- Cell death in tumours

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Dysregulated Apoptosis

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Decrease in apoptosis increase of cell survival

• Cancers (p53 mutation)
• Autoimmune disease (autoreactive lymphocytes not eliminated)

Increase in apoptosis and excess in cell death

• Neurodegenerative disease
• Death of viral infected cells

Front 13

Necrosis vs. Apoptosis

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Front 14

*Thrombosis, Ischaemia, Infarction

Back 14

• What is a thrombus?
• Virchow’s triad
• Fate of a thrombus
• What is an embolus?
• Clinical consequences ofthromboembolism
• Infarction and gangrene
• Microscopy of myocardial infarction