PP 2: MOLECULAR MECHANISM OF CELL INJURY;
CANCER CHARACTERISTICS| TOP SCORES MADE SIMPLE
| TRUSTED TEST SOLUTIONS!
What are the possible causes (initiators) of cell injury? Answer: Hypoxia – due to
ischemia (reduced blood flow), poor oxygenation (e.g. respiratory failure), or decreased
oxygen-carrying capacity of blood (e.g. anemia).
Physical agents – such as trauma, extreme temperatures (heat/cold), radiation, and
electrical injury.
Chemical agents – including toxins like carbon monoxide (CO), asbestos, cyanide, and
insecticides.
Infectious agents – bacteria, viruses, fungi, and parasites.
Immune reactions – can be overactive or misdirected (e.g. autoimmune diseases).
Genetic abnormalities – such as mutations causing defective proteins or metabolism.
Nutritional imbalances – including undernutrition, overnutrition, and deficiencies or
excesses of specific nutrients
What factors determine a cell's response to injury? Answer: Nature, duration, and
severity of the injury – A brief or mild insult might be reversible, whereas prolonged or
severe injury can be lethal.
Type of cell, its current state, and adaptability – For example, cardiac muscle is more
vulnerable to ischemia than skeletal muscle.
Biochemical mechanisms and targets involved – Some injuries affect multiple essential
cellular components like mitochondria, membranes, or DNA, leading to compounded
effects.
What are the major molecular mechanisms of cell injury? Answer: Mitochondrial
damage → leads to ↓ ATP, ↑ ROS, and activation of pro-apoptotic proteins.
Calcium entry into cells → activates destructive enzymes.
Membrane damage → causes leakage of cellular contents and enzymatic digestion.
Protein misfolding and DNA damage → disrupts normal cellular functions, may trigger
apoptosis.Each mechanism often affects multiple critical cellular structures and
functions simultaneously.
1
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, What are the major causes of ATP depletion during cell injury? Answer: Ischemia (lack
of blood flow and oxygen)
Nutrient deprivation
Mitochondrial damage (disrupts ATP production)
Toxins like cyanide (inhibit mitochondrial enzymes)The extent of damage varies
depending on the tissue's ability to use glycolysis (e.g., the liver tolerates low ATP better
than the brain)
What are the consequences of ATP depletion to 5-10% of normal levels? Answer:
Na⁺/K⁺ pump failure → leads to cellular swelling and ER dilation.
Switch to glycolysis → lactic acid builds up, lowering pH, which disrupts enzyme
function.
Glycogen stores are rapidly depleted
Ca²⁺ pump failure → increased cytosolic Ca²⁺
Ribosome detachment from ER → decreased protein synthesis
Mitochondrial and lysosomal membrane injury → irreversible damage
Protein misfolding → triggers the unfolded protein response (a stress response)
What causes mitochondrial damage, and what are the two major consequences?
Answer: Causes:
- ↑ cytosolic Ca²⁺
- Reactive oxygen species (ROS)
- Ischemia
- Inherited mutations
Consequences:
- Mitochondrial permeability transition pore opens → loss of membrane potential and ↓
ATP production.
- Release of cytochrome c and other pro-apoptotic proteins from the space between the
inner and outer mitochondrial membranes → initiates apoptosis.
How can mitochondria by damaged? Answer: 1) ↑cytosolic Ca2+
2) reactive oxygen species (ROS)
3) ischemia
2
APPHIA - Crafted with Care and Precision for Academic Excellence.
CANCER CHARACTERISTICS| TOP SCORES MADE SIMPLE
| TRUSTED TEST SOLUTIONS!
What are the possible causes (initiators) of cell injury? Answer: Hypoxia – due to
ischemia (reduced blood flow), poor oxygenation (e.g. respiratory failure), or decreased
oxygen-carrying capacity of blood (e.g. anemia).
Physical agents – such as trauma, extreme temperatures (heat/cold), radiation, and
electrical injury.
Chemical agents – including toxins like carbon monoxide (CO), asbestos, cyanide, and
insecticides.
Infectious agents – bacteria, viruses, fungi, and parasites.
Immune reactions – can be overactive or misdirected (e.g. autoimmune diseases).
Genetic abnormalities – such as mutations causing defective proteins or metabolism.
Nutritional imbalances – including undernutrition, overnutrition, and deficiencies or
excesses of specific nutrients
What factors determine a cell's response to injury? Answer: Nature, duration, and
severity of the injury – A brief or mild insult might be reversible, whereas prolonged or
severe injury can be lethal.
Type of cell, its current state, and adaptability – For example, cardiac muscle is more
vulnerable to ischemia than skeletal muscle.
Biochemical mechanisms and targets involved – Some injuries affect multiple essential
cellular components like mitochondria, membranes, or DNA, leading to compounded
effects.
What are the major molecular mechanisms of cell injury? Answer: Mitochondrial
damage → leads to ↓ ATP, ↑ ROS, and activation of pro-apoptotic proteins.
Calcium entry into cells → activates destructive enzymes.
Membrane damage → causes leakage of cellular contents and enzymatic digestion.
Protein misfolding and DNA damage → disrupts normal cellular functions, may trigger
apoptosis.Each mechanism often affects multiple critical cellular structures and
functions simultaneously.
1
APPHIA - Crafted with Care and Precision for Academic Excellence.
, What are the major causes of ATP depletion during cell injury? Answer: Ischemia (lack
of blood flow and oxygen)
Nutrient deprivation
Mitochondrial damage (disrupts ATP production)
Toxins like cyanide (inhibit mitochondrial enzymes)The extent of damage varies
depending on the tissue's ability to use glycolysis (e.g., the liver tolerates low ATP better
than the brain)
What are the consequences of ATP depletion to 5-10% of normal levels? Answer:
Na⁺/K⁺ pump failure → leads to cellular swelling and ER dilation.
Switch to glycolysis → lactic acid builds up, lowering pH, which disrupts enzyme
function.
Glycogen stores are rapidly depleted
Ca²⁺ pump failure → increased cytosolic Ca²⁺
Ribosome detachment from ER → decreased protein synthesis
Mitochondrial and lysosomal membrane injury → irreversible damage
Protein misfolding → triggers the unfolded protein response (a stress response)
What causes mitochondrial damage, and what are the two major consequences?
Answer: Causes:
- ↑ cytosolic Ca²⁺
- Reactive oxygen species (ROS)
- Ischemia
- Inherited mutations
Consequences:
- Mitochondrial permeability transition pore opens → loss of membrane potential and ↓
ATP production.
- Release of cytochrome c and other pro-apoptotic proteins from the space between the
inner and outer mitochondrial membranes → initiates apoptosis.
How can mitochondria by damaged? Answer: 1) ↑cytosolic Ca2+
2) reactive oxygen species (ROS)
3) ischemia
2
APPHIA - Crafted with Care and Precision for Academic Excellence.
