1
Advanced Pathophysiology
Study Guide for Test #1
Unit-1
Cellular adaptation, injury, and death
- Apoptosis Vs necrosis
Apoptosis = Programmed cell death (suicide) Necrosis = Unregulated enzymatic digestion of cell
components
- Maintains a balance between cell proliferation and cell
death
– Functions to remove cells so new cells can replace them
– Highly selective process that eliminates injured and aged
cells
- Affects scattered, single cells
- Starts by shrinkage of the cell
- There is membrane-bound fragmentation of the cell
(CELL MEMBRANE STAYS INTACT). As a result,
intracellular enzymes are NOT released into
circulation
- Not associated with inflammatory reaction
- Interferes with cell replacement and tissue regeneration
- Non-distinguishing cell death
- Starts by swelling of the cell
- There is loss of cell membrane integrity >> Lysosomal
enzymes are released extracellularly (blood)
- Triggers inflammatory response in the surroundings
- Role of Na + and Ca ++ in hypoxic cell injury
Steps and mechanisms of cell injury
1. Hypoxia > reduced ATP production inside the cell
2. Failure of Na/K pump > more Sodium (Na) moves into the cell
3. High osmotic pressure > water moves into the cell > cell swelling
4. Dilation of endoplasmic reticulum and detachment of ribosomes > reduced protein synthesis
5. Increased lipid deposition, glycolysis, lactate formation, lowered pH, clumping of nuclear chromatin, increased
membrane permeability
>> Lecture:
Recall > Where sodium goes, water goes. Water will follow sodium and accumulate within the cell, resulting in cellular
edema. With sodium, the cell swells to a certain degree, and the cell membrane gives way/breaks (#6), allowing calcium
to get inside (#7).
When cells are hypoxic, they will accumulate lactic acid. The Na/K pump is a protein molecule and will denature
(breakdown) when exposed to lactic acid, to stop functioning altogether.
6. Loss of cell membrane integrity
7. Increased Calcium (Ca) influx > enzymatic activation > cell damage
8. Disruption of cytoskeleton
9. Mitochondrial membrane damage, lysosome swelling and rupture
10. Cell death (necrosis!)
>> Lecture:
Calcium is the “killer.” Calcium inside the cell is very restricted and is always kept outside the cell. The cell membrane
keeps calcium out; however, in the above scenario, calcium can come in. Calcium activates cellular enzymes and leads
to self-destruction (necrosis!).
