cell injury 2 Flashcards
Apoptosis Other pathways of cell death Autophagy Mechanisms of Cell Injury and Cell Death (43 cards)
what isd apoptosis?
Apoptosis is a pathway of cell death in which cells activate enzymes that degrade the cells’ own nuclear DNA and nuclear and cytoplasmic proteins
why apoptotic bodies is formed?
become highly “edible,” leading to their rapid consumption by phagocytes.
what are the physiological causes of apoptosis?
During normal development of an organism, some cells die and are replaced by new ones.
In mature organisms, highly proliferative and hormone responsive tissues undergo cycles of proliferation and cell loss that are often determined by the levels of growth factors.
what are pathological causes of apoptosis?
severe DNA damage, for example, after exposure to radiation and cytotoxic drugs
The accumulation of misfolded proteins
Certain infectious agents, particularly some viruses
what are the mechanisms of apoptosis?
Mitochondrial pathway
Death receptor pathway
what enzyme is activated in apoptosis?
caspases
which pathway is intrinsic ?and why
mitochondrial
because it originates from signals within the cell itself, particularly in response to internal stressors like DNA damage, oxidative stress, or metabolic dysfunction.
which pathway is responsible in most physiologic and pathologic situation?
mitochondrial
which protien activate caspases-9 and induce apoptosis in mitochondrial pathway ?
cytochrome c
explain mitochondrial pathway
1-cell stress(decreased GF-DNA damage-misfolded protiens)
2-BH3 is activated
3-Bcl-2 and Bcl-xl are inhibited
4- Bax and Bak are activated
5-cytochrome c is released into the cytosol
6- caspases cascade
what is the function of BH3 when activated ?
it inhibit the function of Bcl-2 and Bcl-xl
what is the function of Bcl-2 and Bcl-xl?
it binds to Bax and Bak and keep them inactive
so they control the permeability of mitochondia
Bcl-2 and Bcl-xl are produced in response to what ?
GF
which cell stress can initiate apoptosis?
cells are deprived of growth factors and survival signals
exposed to agents that damage DNA
accumulate unacceptable amounts of misfolded proteins
death receptors in apoptosis?
type I TNF receptor and Fas (CD95).
Atp required for what?
Failure of ATP generation and depletion of ATP in cells will cause what?
1_reduce activity of ATP_dependent plasma membrane sodium pumps
2increase the anaerobic compensatoey glycolysis
3 detachment of ribosomes from rough ER
What happen to plasma membrane when ATP level is reduced
Compensatory anaerobic glycolysis will lead to what?
How ER will be effected from decreased ATP ?
Oxidative stress can be caused by?
How free radicals can lead to cell death?
They’re extremely unstable
So they react readily with inorganic and organic molecules
When they generate in cells they attack nucleic acids , proteins and lipids
What are free radicals
Give 2 pathways for generating ROS
1_ REDOX
( In small amounts in mitochondria as result of respiration and energy generation
2_
*In phagocytic leukocytes (macrophages and neutrophils) as weapons (respiratory/oxidative burst)
*Nitric oxide
