Chapter 2
Altered Cellular and Tissue Biology
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Cellular Injury Mechanisms
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Hypoxic injury
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Ischemia
Anoxia
Cellular responses
• Decrease in ATP, causing failure of sodium-potassium pump
and sodium-calcium exchange
• Cellular swelling
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Reperfusion injury
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Cellular Injury Mechanisms
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Free radicals and reactive oxygen species
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Electrically uncharged atom or group of atoms
having an unpaired electron
 Lipid peroxidation
 Alteration of proteins
 Alteration of DNA
 Mechanisms for inactivation of free radicals
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Free Radical Injury
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The result of oxidative stress
An atom or group of atoms having an
unpaired electron
Unstable molecule
To stabilize itself, it gives up an electron or
steals one from long chains of phospholipids
in cell membranes (lipid peroxidation)
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Oxidation vs. Reduction
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Oxidation
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Losing an electron
Reduction
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Gaining an electron
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Cellular Injury Mechanisms
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Chemical injury
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Lead
Carbon monoxide
Ethanol
Mercury
Social or street drugs
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Unintentional and Intentional
Injuries
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Blunt force injuries
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Application of mechanical energy to the body
resulting in the tearing, shearing, or crushing of
tissues
Contusion vs. hematoma
Abrasion
Laceration
Fractures
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Unintentional and Intentional
Injuries
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Sharp force injuries
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Incised wounds
Stab wounds
Puncture wounds
Chopping wounds
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Unintentional and Intentional Injuries
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Gunshot wounds
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Entrance wounds
• Contact-range entrance wound
• Intermediate-range entrance wound

Tattooing and stippling
• Indeterminate-range entrance wound
 Exit wounds
• Shored exit wound
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Unintentional and Intentional Injuries
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Asphyxial injuries
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Caused by a failure of cells to receive or use oxygen
Suffocation
Strangulation
• Hanging, ligature, and manual strangulation
Chemical asphyxiants
Drowning
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Infectious Injury
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Pathogenicity of a microorganism
Virulence of a microorganism
Disease-producing potential
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Invasion and destruction
Toxin production
Production of hypersensitivity reactions
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Immunologic and Inflammatory Injury
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Phagocytic cells
Immune and inflammatory substances
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Histamine, antibodies, lymphokines, complement,
and enzymes
Membrane alterations
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Injurious Genetic Factors
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
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Nuclear alterations
Alterations in the plasma membrane
structure, shape, receptors, or transport
mechanisms
Examples

Sickle cell anemia and muscular dystrophy
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Injurious Nutritional Imbalances
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Essential nutrients are required for cells to
function normally
Deficient intake
Excessive intake
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Temperature Extremes
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Hypothermic injury
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Slows cellular metabolic processes
ROS production
Hyperthermic injury
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Heat cramps
Heat exhaustion
Heat stroke
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Atmospheric Pressure Changes
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Sudden increases or decreases in
atmospheric pressure
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Blast injury
Decompression sickness or caisson disease
• “The bends”
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Ionizing Radiation
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Any form of radiation capable of removing
orbital electrons from atoms
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X-rays, gamma rays, alpha and beta particles
Mechanism of damage
Effects of ionizing radiation

Somatic, genetic, fetal
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Cellular Injury
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Illumination injury
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Eyestrain, obscured vision, and cataract
formation
 Caused by light modulation
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Mechanical stresses
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Physical impact, irritation, overexertion
Noise

Acoustic trauma and noise-induced hearing
loss
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Manifestations of Cellular Injury
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Cellular accumulations (infiltrations)
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Water
Lipids and carbohydrates
Glycogen
Proteins
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Manifestations of Cellular Injury
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Cellular accumulations (infiltrations)
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Pigments
• Melanin, hemoproteins, bilirubin
Calcium
Urate
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Cellular Death
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Necrosis
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Sum of cellular changes after local cell death and
the process of cellular autodigestion (autolysis)
Processes
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Karyolysis
• Nuclear dissolution and chromatin lysis
 Pyknosis
• Clumping of the nucleus
 Karyorrhexis
• Fragmentation of the nucleus
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Necrosis
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Coagulative necrosis
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Kidneys, heart, and adrenal glands
Protein denaturation
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Necrosis
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Liquefactive necrosis
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Neurons and glial cells of the brain
Hydrolytic enzymes
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Necrosis
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Caseous necrosis
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Tuberculous pulmonary infection
Combination of coagulative and liquefactive
necrosis
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Necrosis
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Fat necrosis
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Breast, pancreas, and other abdominal organs
Action of lipases
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Necrosis
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Gangrenous necrosis
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Clinical term
Dry vs. wet gangrene
Gas gangrene
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Apoptosis
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Programmed cellular death
Mechanisms
Necrosis vs. apoptosis
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Aging and Altered Cellular
and Tissue Biology
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Aging vs. disease
Normal life span
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Theories of Aging
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Accumulation of injurious events
Genetically controlled program
Theories
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Genetic and environmental lifestyle factors
Alterations of cellular control mechanisms
Degenerative extracellular changes
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Aging
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Cellular aging
Tissue and systemic aging
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Frailty
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Somatic Death
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Death of an entire person
Postmortem changes
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Algor mortis
Livor mortis
Rigor mortis
Postmortem autolysis
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