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Chapter 2
Mechanisms of Disease
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© 2010
© 2010
Delmar,
Delmar,
Cengage
Cengage
Learning.
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Causes of Disease
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Hereditary
Trauma
Inflammation/infection
Hyperplasias/neoplasms
Nutritional imbalance
Impaired immunity
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Hereditary
• Error in individual’s genetic or chromosomal
makeup
• Congenital
– Disease present at birth
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Hereditary
• Classifications of hereditary diseases:
– Single gene abnormality
– Abnormality of several genes
– Abnormality of a chromosome
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Trauma
• Physical injury or external force
• Type of traumatic disease varies with:
– Age
– Race
– Residence
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Trauma
• Classifications in order of prevalence:
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Motor vehicle accidents
Falls
Drowning
Burns
Ingested or inhaled objects
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Trauma
• Classifications in order of prevalence:
– Poisoning
– Penetrating injuries
– Physical abuse
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Inflammation/Infection
• Inflammation
– Protective immune response triggered by injury or irritant
• Infection
– Invasion of microorganisms into tissues causing cell or
tissue injury
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Hyperplasias/Neoplasms
• Hyperplasias
– Overgrowth in response to some type of stimulus
• Neoplasms
– Also known as tumors
• Oncology
– Study of cancer
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Hyperplasias/Neoplasms
• Neoplasm classifications:
– Benign
• Limited growth
– Encapsulated
• Enclosed in capsule
– Malignant
• Uncontrolled growth
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Hyperplasias/Neoplasms
• Cancer
– Malignant tumor
• Metastasize
– Moves and spreads
• Metastatic
– Moves from site of origin to secondary site in body
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Nutritional Imbalance
• Usually related to over or under consumption
• Cachexia
– Ill, thin, wasted appearance
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Nutritional Imbalance
• Alternatives:
– Parenteral
• Administered by injection
– Enteral
• Nutrition through small intestine
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Impaired Immunity
• Body’s first line of defense:
– Skin, mucous membranes, tears, and secretions
• Protective qualities of immune system:
– Leukocytes kill foreign invaders
– Body reacts to antigens by producing antibodies
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Impaired Immunity
• Antigens
– Substances that cause harm and set off specific response
• Antibodies
– Also known as immune bodies
– Proteins that render antigen harmless
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Impaired Immunity
• Common ways immune system fails:
– Allergy
– Autoimmunity
– Immunodeficiency
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Aging
• Degeneration
– Disease related to age
– Tissue degeneration changes functional activity to lower or
lesser level
– Body’s ability to repair and replace itself slows down with
aging process
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Cellular Injury
• Causes of cellular injury and death:
– Hypoxia
• Not enough oxygen
– Anoxia
• No oxygen
– Drug or bacterial toxins
– Viruses
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Cellular Adaptation
• Types:
– Atrophy
• Decrease in cell size
– Hypertrophy
• Increase in cell size
– Hyperplasia
• Increase in cell number
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Cellular Adaptation
• Types:
– Dysplasia
• Alteration in size, shape, and organization of cell
– Metaplasia
• Cell changes to another type
– Neoplasia
• Development of new type of cell with uncontrolled growth pattern
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Atrophy of a Cell
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Hypertrophy of a Cell
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Hyperplasia of a Cell
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Dysplasia of a Cell
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Metaplasia of a Cell
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Neoplasia of a Cell
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Cell and Tissue Death
• Necrosis
– Cellular death
• Ischemia
– Decreased blood flow
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Cell and Tissue Death
• Infarct
– Area of dead cells
• Gangrene
– Saprophytic bacteria involved in necrotic tissue
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Organism Death
• Morbidity
– State of being diseased
• Criteria for brain death:
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Lack of response to stimuli
Loss of all reflexes
Absence of respirations
Lack of brain activity on electroencephalogram (EEG)
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