Cell injury

Question 1

General causes of injured cells

Answer 1

-Changes in available nutrients (like O2)
-Direct cell damage (microorganisms, toxins, physical forces)

Question 2

Cell injury susceptibility

Answer 2

-Cells have widely variable resistance
-Metabolic status will influence
-Neurons and cardiac myocytes susceptible to hypoxia
-Fibroblasts or squamous cells can survive absence better

Question 3

Mechanisms of cell injury

Answer 3

-Loss of membrane integrity
-Loss of ability to produce energy
-Genetic damage

Question 4

Loss of membrane integrity

Answer 4

Cell membranes breakdown and loose ability to segregate reaction within cell or can loose barrier to environment and loose gradients

Question 5

Loss of ability to produce energy

Answer 5

ATP is insufficient to support cell functions

Question 6

Mechanism of loss of membrane integrity

Answer 6

-Free radical-induced damage
-Phospholipase-induced damage
-Direct membrane damage

Question 7

Free radical injury

Answer 7

Unpaired electrons that readily react with surrounding molecules, causing chain reaction as electron passed to molecule to molecule

Question 8

Where are free radicals formed

Answer 8

-During oxidation reduction reactions during aerobic respiration
-Biotransformation of chemical substances
-Nitric oxide metabolism

Question 9

Effects of reactive oxygen metabolites

Answer 9

-Protein and membrane degradation
-DNA damage
-Inflammation

Question 10

Protective mechanisms against free radical injury

Answer 10

-Vitamins A,C, and E
-Iron and copper binding proteins
-Specific enzymes (superoxide dismutase, catalase etc)

Question 11

Phospholipase-induced injury

Answer 11

Activated membrane phospholipases cleave phospholipids out of the membrane. Can be because of increased Ca or because of decreased energy

Question 12

Causes of direct membrane injury

Answer 12

-Bacterial toxins
-Xenobiotics
-Complement

Question 13

Pathways in which ATP is produces

Answer 13

-Oxidative phosphorylation
-Anaerobic glycolysis

Question 14

Mechanisms of the loss of ability to produce energy

Answer 14

-Failure of energy dependent membrane pumps
-Decreased intracellular pH
-Decreased protein synthesis
-Cytoskeletal degradation
-Membrane degradation
-Leakage of organelle contents
-Organelle dysfunction

Question 15

Role of calcium in cell injury

Answer 15

-Mitochondrial injury
-Phospholipase activation
-Protease activation
-Endonuclease activation

Question 16

Effects of genetic injury

Answer 16

-No effect
-Cell dysfunction leading to disease
-Cell transformation leading to neoplasia
-Cell death

Question 17

Sublethal injury types

Answer 17

-Cell swelling
-Intracellular accumulations
-Neoplastic transformation

Question 18

Lethal injury results

Answer 18

-Apoptosis
-Necrosis

Question 19

Mechanism of cell swelling

Answer 19

Membrane ion pumps fail to maintain osmotic gradients so water enters the cell. Look swollen and vacuolated or hydropic change. Reversible

Question 20

Intracellular accumulations

Answer 20

Abnormal metabolism, functional demands exceeding capability, or exposure to agents leads to accumulations either endogenous or exogenous. Reversible

Question 21

Examples of endogenous intracellular accumulations

Answer 21

-Metabolic storage diseases
-Lipidosis
-Glycogenosis
-Intracellular pigments

Question 22

Lipidosis

Answer 22

Triglyceride accumulation that can be physiological or pathological

Question 23

Pathologic causes of lipidosis

Answer 23

-Hepatotoxins
-Hypoxia
-Starvation

Question 24

Morphology of lipidosis

Answer 24

Cytoplasmic vacuoles of variable size

Question 25

Endogenous accumulations due to glycogenosis

Answer 25

Glycogen accumulates due to abnormal metabolism. Cells look swollen. See in diabetes mellitis

Question 26

Hemosiderin endogenous accumulations

Answer 26

Intracellular aggregates of ferritin associated with increased rbc senescence or hemolysis

Question 27

Lipofuscin-ceroid endogenous accumulations

Answer 27

Undegradable remnants of oxidized membrane lipids. It can accumulate from aging or membrane oxidation

Question 28

Exogenous intracellular accumulations

Answer 28

-Viral inclusions -Carbon -Non nutritive minerals (lead)

Question 29

Sublethal injury leading to transformation

Answer 29

Due to genetic injury can be transformed and are not injured now but detrimentally changed

Question 30

Morphology of transformed cells

Answer 30

-May be normal or hyperplasia -Anaplasia -Pleomorphism

Question 31

Lethal cell injury

Answer 31

Insult exceeds ability to adapt or responds. Can progress here from sublethal injury

Question 32

Physiologic Causes of apoptosis

Answer 32

-Patterned death during embryogenesis -Hormone/cytokine induced -Maintain balance during proliferation -Removal of cell no longer needed -Removal of self reactive lymphocytes

Question 33

Pathologic causes of apoptosis

Answer 33

-Unrepaired DNA damage -Heat -Hypoxia -Viral infection -Physical pressure

Question 34

Necrosis

Answer 34

Death from injury that disrupts the ability to function and happens after it is dead and is a passive process. Autolysis of cell in living animal

Question 35

Autolysis

Answer 35

Self digestion of cell or tissue

Question 36

Postmortem autolysis

Answer 36

Self digestion of cells/tissues/organs after animal dies

Question 37

Causes of necrosis

Answer 37

-Hypoxia -Direct membrane injury -Many of same things that initiate apoptosis may cause this if severe enough

Question 38

Mechanism of necrosis

Answer 38

-Degradation of lytic enzymes can come from same cell (autolysis) or from responding cell (heterolysis)

Question 39

Necrosis morphology

Answer 39

-Eosinophilia -Smooth, homogenous cytoplasm -Vacuolation -Nuclear degeneration -Inflammation response

Question 40

What type of cell destruction is always pathologic and causes inflammation

Answer 40

Necrosis

Question 41

Post mortem autolysis

Answer 41

Cell and tissue degradation that occurs following death of an animal. Occurs in a predictable fashion

Question 42

Difference in ante mortem and post mortem autolysis

Answer 42

No inflammation or host response in post mortem and occurs in predictable fashion