Cell Injury Concepts

Question 1

What is hypoxia due to?

Answer 1

Ischemia or decreased O2 carrying capacity of blood

Question 2

What are some physical agents of cell injury?

Answer 2

Trauma, temperature, radiation, shock

Question 3

Name some chemical agents and drugs that may cause cellular injury

Answer 3

• Biological agents
• Poisons/pollutants
• Industrial hazards
• Social and therapeutic drugs

Question 4

List the themes of cellular injury

Answer 4

• Hypoxia
• Physical agents
• Chemical agents and drugs
• Infectious agents
• Immunological reactions
• Genetic defects
• Nutritional imbalances

Question 5

Lack of oxygen (or oxygen excess) causes decreased synthesis of…

Answer 5

ATP

Question 6

Increases in intracellular calcium and loss of calcium homeostasis lead to activation of…

Answer 6

calcium-dependent enzymes

Question 7

With an increase in calcium in the cell, enzymes turn on causing…

Answer 7

cell death

Question 8

Depletion of ATP causes…

Answer 8

loss of membrane function and intracellular processes, thus cell death

Question 9

Defects in membrane permeability have what effect on the cell?

Answer 9

Holes in membranes, the cell’s or its organelles’, kill the cell

Question 10

If a cell has decreased pH and ATP, and has swollen, is this reversible or irreversible?

Answer 10

Reversible

Question 11

If ribosomes have detached from the rough endoplasmic reticulum, is this reversible or irreversible?

Answer 11

Reversible

Question 12

What is the point of no return/irreversibility?

Answer 12

Mitochondrial vacuolization

Question 13

What happens after mitochondrial vacuolization?

Answer 13

• Lysosome rupture
• Ca+ release into cytoplasm

Question 14

What does cellular swelling mean for the cell’s activity?

Answer 14

Loss of activity of Na+/K+ ATPase pump activity meaning ion influx

Question 15

What does steatosis mean for the cell’s activity?

Answer 15

Altered metabolism/transport of triglycerides

Question 16

Is steatosis reversible or irreversible?

Answer 16

Reversible, but may become irreversible

Question 17

Is cellular swelling reversible or irreversible?

Answer 17

Reversible, but may become irreversible

Question 18

What is pyknosis?

Answer 18

Small, shrunken, and dark nuclei

Question 19

What is karryorrhexis?

Answer 19

Fragmented nuclei

Question 20

What is karyolysis?

Answer 20

Faded nuclei

Question 21

In hypoxic/ischemic injury, is compromised aerobic respiration and increased rate of anaerobic glycolysis reversible?

Answer 21

Yes, these are before the point of no return

Question 22

Is lysosomal membrane rupture/activation of Ca+ dependent enzymes reversible?

Answer 22

No, after the point of no return

Question 23

What are free radicals?

Answer 23

Unstable atoms that can injure the cell

Question 24

Free radicals serve what purpose normally?

Answer 24

A final common pathway in a variety of cell processes

Question 25

Chemical and radiation injury, cellular aging, oxygen toxicity, and microbial killing by phagocytes can all be caused by...

Answer 25

free radicals

Question 26

Free radicals consist of...

Answer 26

chemical species

Question 27

What are three traits of chemical species of free radicals?

Answer 27

* Highly reactive * Autocatalytic * Unstable

Question 28

Free radical induced damage involves:

Answer 28

* Lipid peroxidation of cell membranes * Oxidative modification of cellular proteins * Damage to cellular DNA

Question 29

What enzymes are used to turn O2 into O2- (superoxide anion)?

Answer 29

NADPH oxidase and xanthine oxidase

Question 30

O2- (superoxide anion) makes more...

Answer 30

free radicals

Question 31

What enzyme and coenzyme is used to turn O2- into H2O2?

Answer 31

Superoxide dismutase and H2O

Question 32

Name H2O2

Answer 32

Hydrogen peroxide

Question 33

What enzyme is used to turn H2O2 into H2O + O2?

Answer 33

Catalase

Question 34

What would happen without free radicals?

Answer 34

Most immunological processes would cease

Question 35

What are the attributes of hydrogen peroxide (H2O2)?

Answer 35

Forms free radicals via Fe2+- catalyzed Fenton reaction Diffuses widely within the cell

Question 36

What is the Fenton reaction?

Answer 36

Fe2+ + H2O2 --> Fe3+ + OH- + .OH (free radical)

Question 37

What is the Haber-Weiss reaction?

Answer 37

O2- + H+ + H2O2 --> O2 + H2o + .OH (free radical)

Question 38

Where is superoxide anion (O2-) generated?

Answer 38

Generated by leaks in the electron transport chain and some cytosolic reactions

Question 39

Superoxide anion (O2-) with xanthine oxidase produces...

Answer 39

other ROS

Question 40

Does superoxide anion (O2-) diffuse from its origin?

Answer 40

Does not readily diffuse far from its origin

Question 41

Where is hydroxyl radical (.OH) generated?

Answer 41

Generated from H2O2 by Fe+-catalyzed Fenton reaction

Question 42

Which intracellular radical is most responsible for attack on macromolecules?

Answer 42

Hydroxyl radical (.OH)

Question 43

What are the attributes of peroxynitrite (ONOO.)?

Answer 43

Formed from the reaction of nitric oxide (NO) with O2-; damages macromolecules

Question 44

What are lipid peroxide radicals (RCOO.)?

Answer 44

Organic radicals produced during lipid peroxidation

Question 45

What are the attributes of hypochlorous acid (HOCl)?

Answer 45

Produced by macrophages and neutrophils during respiratory burst that accompanies phagocytosis Dissociates to yield hypochlorite radical (OCL-)

Question 46

What is Fe2+?

Answer 46

Ferrous iron

Question 47

Activated oxygen will lead to...

Answer 47

membrane damage thus cell injury