Cell Injury and Cell Death

Endogenous or Exogenous: Hypoxia, immunologic rxns, genetic abnormality, aging

Endogenous

Endogenous or Exogenous: Toxins, infectious pathogens, nutritional imbalance, physical agents

Exogenous

Examples of Cell adaptations to stress

• Hypertrophy

• Hyperplasia

• Atrophy

• Metaplasia

Increase in cell size and increase in organ size (not increase in # of cells)

Hypertrophy

Increase in number of cells

Hyperplasia

Difference between Hyperplasia and neoplasia?

Hyperplasia more controlled

Decrease in size of cells

Atrophy

Cell type is replaced by new cell type

Metaplasia

Type of cell reaction to smoking happens in the lungs

Columnar cells repalced by squamous in hopes of being more resistant

Disordered cellular growth. Can reverse or progress to cancer

Dysplasia

Failure of cell production during embryogenesis (missing structures)

Aplasia

Decrease in cell production during embryogenesis (relatively small structure)

Hypoplasia

Lack of oxygen to cells

Hypoxia

No blood to cells

Ischemia

Induced by Reactive Oxygen species

Oxidative Stress

Chemically unstable molecules that attact nucleic acid, proteins and lipids

Free Radicals

Are ROS a normal biproduct from respiration, and produced in neutrophils and macrophages?

Yes

Ways of accumulating ROS

Absorbing radiant energy, metabolism of exogenous chemicals, inflammation

Ways to minimize damage from ROS

• Free radical scavengers

• Anti-oxidants

Source of antioxidants

Endogenous AND Exogenous

Examples of antioxidants

Vitamins E, A, C and B-carotene

Most common reversible cell injury

Swelling

Three causes of Irreversible cell damage

• Inability to restore mitochondrial function

• Loss of structure and function of plasma membrane

• Loss of DNA and Chromatin structural integrity

Condensation of nucleus

Pyknosis

Fragmentation of Nucleus

Karyorrhexis

Dissolution of Nucleus

Karyolysis

• Infarct solid organs

• Tissue appears firm

• Cell outlines preserved, no nucleus

Coagulative necrosis

• Bacterial / fungal infections, hypoxia in CNS

• Dissolution of tissue into viscous liquid

Liquefactive Necrosis

• Ischemia of limb

• Coagulative necrosis resembling mummified tissue

Gangrenous Necrosis

• Tuberculosis, walling off infection

• Cheese like appearance

• Granulomas

Caseous Necrosis

Group of Macrophages

Granuloma

• Lipase breaks down fat cells

• calcium accumulates

• Pancreatitis

• Chalky deposits in fat

• No nuclei, outline fat cells

Fat Necrosis

• immune mediated conditions

• hypertension

• Pink deposits in wall of blood vessels

Fibrinoid Necrosis

Programmed cell death

Apoptosis

Necrosis or Apoptosis induces NO inflammatory response?

Apoptosis: much cleaner

Steps of Apoptosis

• Cell shrinks

• Nucleus condenses and fragments

• apoptotic bodies fall from cell

• NO inflammation