Pathology Lecture 1: Cellular Injury and Adaptation Flashcards

0
Q

Define reversible and irreversible cellular injury and what is the result of irreversible cellular injury?

A
  1. Reversible: damage may be repaired and cell will return to normal
  2. Irreversible: stress causes repair mechanisms to be destroyed/inactivated, reestablishment of homeostasis is insufficient for repair
  3. Cellular necrosis
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1
Q

Define homeostasis

A

Balance of physiological and biochemical processes in the body

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2
Q

What are causes of cellular injury?

A
  1. Hypoxia
  2. Physical causes
  3. Chemical causes
  4. Infectious causes
  5. Immune reactions
  6. Genetic derangements
  7. Nutritional imbalances
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3
Q

Define hypoxia and anoxia and their causes

A
  1. Hypoxia: Decreased oxygen supply to cell / inability to utilize oxygen
  2. Anoxia: complete absence of oxygen
  3. Causes: Decreased blood flow to tissue (ischemia)
    Decreased oxygen availability to blood (suffocation)
    Decreased oxygen carrying capacity of blood (anemia)
    Inhibited oxygen utilization by cell (CO)
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4
Q

What are physical causes of cellular injury?

A
  1. Mechanical trauma
  2. Temperature extremes
  3. Atmospheric pressure variation
  4. Radiation
  5. Electrical injury
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5
Q

What are chemical causes of cellular injury?

A
  1. Simple agents (ie. glucose, sodium, potassium)
  2. Poisons (cyanide, arsenic)
  3. Pollutants (air, water)
  4. Insecticides
  5. Herbicides
  6. Industrial products
  7. Drugs (therapeutic or recreational
  8. Alcohol
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6
Q

What are infectious causes of cellular injury?

A
  1. Bacteria
  2. Ricketsia
  3. Fungi
  4. Viruses
  5. Parasites
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7
Q

What are immune reactions causing cellular injury?

A
  1. Hypersensitivity reactions

2. Autoimmune disease

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8
Q

What are genetic derangements that cause cellular injury?

A
  1. Congenital malformations

2. Genetic defects and mutations

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9
Q

What are nutritional imbalances that cause cellular injury?

A
  1. Deficiencies
  2. Excess
  3. Malabsorption
  4. Altered utilization
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10
Q

What are sites of cellular injury?

A
  1. Cellular membrane
  2. Aerobic respiration
  3. Enzyme/protein synthesis
  4. Genetic apparatus
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11
Q

What are examples of secondary reversible cellular injuries?

A
  1. Decreased aerobic respiration
  2. Anaerobic glycolysis
  3. Cellular edema
  4. Increased lactic acid
  5. Altered protein synthesis
  6. Structural alterations in lipid membranes
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12
Q

What are examples of secondary irreversible cellular injuries?

A
  1. Vacuolization of mitochondria
  2. Plasma membrane damage
  3. Lysosomal swelling
  4. Loss of proteins, enzymes, and RNA
  5. ATP depletion
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13
Q

What are mechanisms of cellular injury?

A
  1. Sites of cellular injury
  2. Free radical production
  3. Chemical injury
  4. Viral injury
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14
Q

What are free radical production cellular injury?

A

Free radicals activated by oxygen/carbon species are unstable molecules that react with cellular molecules (membrane lipids, nucleic acids) causing injury. Ie. excess oxygen, radiotherapy

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15
Q

What is chemical cellular injury?

A
  1. Direct acting chemicals: combine directly with critical components of cellular organelles
  2. Toxic metabolizes: chemicals must be metabolized to an active form ie direct covalent binding or free radical formation
16
Q

What is viral cellular injury?

A
  1. Viral replication interferes with cellular mechanisms resulting in cellular damage
  2. Immunological response - viral tropism
  3. Cell lysis / cellular inclusions
17
Q

What are 3 types of irreversible cell injury?

A
  1. Autolysis
  2. Heterolysis
  3. Apoptosis
18
Q

Define autolysis

A

Cellular digestion and desaturation caused by enzymes produced by the necrotic cell itself.

19
Q

Define heterolysis

A

Cellular injury and denaturation caused by enzymes or chemicals produced by a cell other than that which is affected.

20
Q

Define Apoptosis

A

Individual cell death within a population of cells. Fragmentation of a single cell.

21
Q

What are types of necrosis?

A
  1. Coagulation necrosis
  2. Liquefaction necrosis
  3. Fat necrosis
  4. Caseation necrosis
  5. Gangrenous necrosis
22
Q

Define coagulation necrosis

A

Cells lose their nucleus with preservation of the overall cellular shape due to denaturation of nuclear proteins and enzymes. Can turn into liquefaction necrosis
Specific organs - heart, kidney, and skeletal muscle

23
Q

Define liquefaction necrosis

A

Characterized by liquefaction of tissues involved. Caused by hydrolytic enzymes which cause both autolysis and heterolysis.
Occurs in brain, abdominal viscera, and bacterial infected tissues

24
Q

Define fat necrosis

A

Caused by action of lipases upon adipose tissue. Characterized by saponification of fat with a resultant chalky white consistency. May develop calcification over time.
Occurs in pancreas and traumatic adipose trauma.

25
Q

Define caseation necrosis

A

Characteristically a combination of coagulation and liquefaction necrosis, it is characterized by cavity areas containing friable, granular, soft “cheesy” proteinaceous material (casein), surrounded by multinucleated giant cells, lymphocytes, and macrophages.
Structure formed is called granuloma.
98% from TB, 2% from fungal infection

26
Q

Define gangrenous necrosis

A

Occurs in tissue undergoing necrosis secondary to ischemia with subsequent bacteria infection or following trauma
Two types
1. Dry gangrene
2. Wet gangrene

27
Q

What is dry gangrene necrosis?

A

Caused by ischemia with subsequent necrosis and drying of tissue. Tissue assumes blackened and mummified appearance and coagulation necrosis predominates.

28
Q

What is wet gangrene necrosis?

A

Tissue assumes soft, green-black, foul smelling purulent consistency caused by liquefaction of tissues following release of autolytic, heterolytic, and bacterial enzymes. Liquefaction necrosis predominates.

29
Q

What are types of intracellular accumulations?

A
  1. Normal substance produced in excess
  2. Abnormal substances produced within or outside of the cell
  3. Pigments
30
Q

What are general principles of intracellular accumulations?

A
  1. May be harmless or toxic
  2. May occur in cytoplasm or the nucleus
  3. May be produced by the cell containing them elsewhere
31
Q

Define Cellular adaptation and it’s types

A

Under certain types of non-lethal stress, cells may adapt with resultant alterations of growth and differentiation

  1. Atrophy
  2. Hypertrophy
  3. Hyperplasia
  4. Metaplasia
  5. Dysplasia
32
Q

Define atrophy and list causes

A

Decrease in cell size due to loss of cell substance with net effete of decreased tissue mass.
Causes: decreased workload, loss of innervation, decreased blood supply, malnutrition, loss of endocrine stimulation, aging, and pressure

33
Q

Define hypertrophy and give physiologic and pathologic examples

A

Increase in cell size with net effect of increased tissue mass. Hypertrophy may be caused by increased functional demand on the cell or increased stimulation by hormones.
Physiologic - uterine enlargement during pregnancy
Pathologic - cardiac hypertrophy in hypertension or valvular incompetence

34
Q

Define hyperplasia and give physiologic and pathogenic examples

A

Increase in cell number with net effect of increased tissue mass. Does not occur in nerve, skeletal muscle, or cardiac muscle
Physiologic - Hormonal: epithelium of breast/uterus during puberty/pregnancy
Compensatory: tissue mass increase after damage
Pathogenic - abnormal hormonal stimulation

35
Q

Define metaplasia

A

Reversible change in which one cell type is replaced by another cell type as a result of some stress. Initially benign, but can become malignant.

36
Q

Define dysplasia

A

A deranged development in cells that have been stimulated to undergo proliferation with atypical cytologic alterations. May be precursor to cancer.