lectures 23 and 24 Cell Injury (Hudmon) Flashcards
How do cells respond to injury
When a cell encounters stress or injury it will undergo adaptation to bring it back to homeostasis which is just a steady state
what are 5 major cellular adaptations in response to injury or stimuli.
1.Hypertrophy (changing size)
- this does not mean number of cells increase just the size of them which causes the organ to increase.
2.Hyperplasia (increasing number)
- does not affect cell size
3.Atrophy (decrease in size)
4.metaplasia (chang in form)
5.Dysplasia (change in organization)
What are 8 causes of cell injury and be able to state one example for each
- Oxygen deprivation
- ischemia which is the loss of oxygenated blood supply to tissue
2.Chemical agents
- an example is poisons - Infectious agents
-viruses and bacteria - immunological reactions
- autoimmune disease - Genetic defects
- sickle cell anemia - Physical agents
- heat, cold - Nutritional Imbalances
-nutritional deficiencies - aging
- damage by ROS
what are the characteristics of reversible versus irreversible cell injury
Reversible injury is the duration of injury that still allows for the cell to function completely normally
Characteristics of Reversible injury include: cellular swelling and fatty change
Irreversible is the duration of injury that can no longer be reversed. Cell death begging to happen and cell function is decreased
Characteristics of Irreversible injury include: inability to reverse mitochondrial dysfunction, and profound disturbance in membrane function
Explain the mechanisms of cell injury
we have a normal cell that soon gets damaged and with reversible damage we have processes in the cell that can reverse and recover the cell back to a normal cell
For irreversible the internal organelle is becoming extremely damaged we will see swelling of the mitochondria. With this extreme damage, there is no saving the cell and it soon leads to necrosis which is an explosion of the cell and this will result in inflammation in the site where the cell is present.
What are two apoptotic pathways and their causes
Mitochondrial Pathway- Cell injury like growth factor withdrawal, DNA damage, and protein misfolding that is sensed by Bcl-2 family sensors that will upregulate Bax and Bak that will cause the mitochondria to release cytochrome C and pro-apoptotic
Death receptor pathway - receptor-ligand interactions that cause endonuclease activation and breakdown of the cytoskeleton
Explain the difference between apoptosis and necrosis
Apoptosis is programed cell death and it doesn’t cause any reaction to the cells surrounding it
Necrosis is death of a cell due to injury that is so harmful it cannot be reversed. The cell ends up exploding and causing inflammation to the site of where it died
Explain the role of major players in the two apoptotic pathways and DNA fragmentation
Bax and Bak are upregulated by bcl-2 family sensors that are triggered when damage is sensed in the cell. Bax and Bak will will created this pores upon binding on the surface of the mitochondrial outer membrane and these pores release cytochrome c
Cytochrome C will then bind to Apaf-1 which will become apoptosome that will cleave procaspase-9 into the active form which will go on to activate procaspase-3 through cleavage and once we have procaspase-3 active then apoptosis occurs
How to reverse oxidative stress on a cell
SOD will convert o2 to peroxide
Glutathione will convert OH to peroxide
Catalase will convert this peroxide to water and oxygen
ATP decrease
can be very dangerous for a cell because once it losses ATP it cannot control functions inside the cell like calcium levels. It also will cause swelling because water will flow in with sodium because these ATP dependent pumps aren’t being regulated. it will also increase production of lactic acid which will thus decrease ph and to a certain extend if ATP levels do not get fixed the cell will die
Damage caused by OFRs and ROS
these will cause protein and DNA modification and also lead to cleavage of DNA and even modification of lipids
