Tissue injury

Question 1

Four key aspects of the disease process:

Answer 1

Etiology-causation (genetic, acquired, or both)
Pathogenesis- (cellular, biochemical and molecular mechanisms of development-often we only know part of the story)
Molecular or morphologic alterations
Clinical manifestations

Question 2

Define hypertrophy:

Answer 2

Increase in cell SIZE, resulting in increase in size of organ or tissue

• can be physiologic or pathologic
• results from increased production of cellular proteins
• can occur as small as at the organelle level (Ex: smooth ER enlargement in hepatocytes of alcoholics)

Question 3

Define hyperplasia:

Answer 3

Increase in the NUMBER of cells, resulting in increase in size of organ or tissue

• occurs if cells can divide
• can be physiologic (hormonal or compensatory) or pathologic (excesses of hormones or growth factors); new cells may arise from mature cells or tissue stem cells

Question 4

Define atrophy:

Answer 4

Decrease in cell size and number, resulting in reduced size of tissue or organ
-can be physiologic (fetal development) or pathologic
Common causes:
-decreased workload
-loss of inervation
-diminished blood supply (decreased nutrient supply)
-inadequate nutrition
-loss of endocrine stimulation
-pressure

results from decreased protein synthesis and increased protein degredation

Question 5

Define metaplasia:

Answer 5

Adaptive response in which one differentiated type of cell is replaced by another cell type

results from reprogramming of stem cells present in normal tissue or reprogramming of undifferentiated mesenchymal cells

Ex: columnar ciliated lung cells –> squamous in smokers

may be reversible if stimulus is removed

**predisposition to metaplasia may lead to malignancy

Question 6

Define ischemia:

Answer 6

deficiency of oxygen due to reduced blood flow

Question 7

Define coagulative necrosis:

Answer 7

Architecture of dead cell is preserved (INFARCT)

Question 8

Define liquefactive necrosis:

Answer 8

digestion of dead tissue results in liquid viscous mass; typically seen in focal bacterial infection (occasionally fungal too); the microbe stimulates the accumulation of neutrophils which liberate tissue destroying enzymes

Pus

Question 9

Define gangrenous necrosis:

Answer 9

clinical term, not specific pattern, usually applied to necrosis of a limb undergoing coagulative ischemic necrosis

Question 10

Define caseous necrosis:

Answer 10

Cheese-like necrosis, associated with necrotizing granulomas, seen with TB and fungal infections

Question 11

Define fat necrosis:

Answer 11

focal areas of fat destruction, look like fat cells minus presence of nucleus

Question 12

Define fibroid necrosis:

Answer 12

Pattern of necrosis seen in immune reactions involvong vessels

Question 13

Define infarction:

Answer 13

coagulative necrosis; cell architecture is preserved

Question 14

Six biochemical mechanisms of cell injury:

Answer 14

1. depletion of ATP
2. mitochondrial damage
3. influx of Ca and loss of Ca homeostasis
4. accumulation of oxygen derived free radicals
5. defects in membrane permiability
6. damage to DNA proteins

Question 15

How can reperfusion exacerbate ischemic injury?

Answer 15

increase free radicals, influx of neutrophils (increased inflammation), influx of Ca, activation of complement system

Question 16

Define eosinophilic as it pertains to appearance under a microscope:

Answer 16

more pink

Question 17

Define necroptosis:

Answer 17

programmed cell necrosis; starts with binding of ligand to receptor like extrinsic apoptosis but subsequent pathway is resemblant of necrosis

Question 18

Define pyroptosis:

Answer 18

programmed cell death occuring in cells infected by microbes

Question 19

Two situations of pathologic calcification:

Answer 19

1. dystrophic calcification (necrosis associated, normal serum calcium level)
2. metastatic calcification; due to hypercalcemia secondary to disordered calcium metabolism (elevated serum calcium)