L3, L4- Cell Injury and Adaptations Flashcards
define the four aspects of disease process
1) etiology = cause
2) pathogenesis = mechanism
3) morphology = appearance
4) functional consequences = clinical significance
a normal cell in homeostasis can undergo (1) to induce an adaptation, or undergo (2) resulting in (3)
1- stress
2- injurious stimulus
3- cell injury
Note- if cell can’t adapt to stress, cell goes into cell injury
cell injury can be (1) resulting in (2) or (3) resulting in (4) or (5)
1- mild / transient 2- reversible injury (--> back to normal once stimulus removed) 3- severe / progressive 4- necrosis 5- apoptosis (4/5) = irreversible injury
list the 6 causes of cell injury
- metabolic
- physical
- chemical
- immunologic
- genetic
- biologic (microbes)
list the 4 most vulnerable mechanisms of cell injury
1) cell membrane integrity
2) ATP production (oxidative phosphorylation)
3) protein synthesis (RER)
4) genetic apparatus (DNA)
list the 5 organelles susceptible to cell injury
- plasma membrane
- SER
- mitochondria
- lysosomes
- nucleus / nucleolus
Plasma membrane cell injury is usually due to (1) or (2), but may also include the following: (3). (T/F) Tears / damage to plasma membrane can never be repaired and result in cell death.
1- trauma
2- free radicals
3- enzymes, chemicals, poisons
4- False, if not too severe tears can be repaired
SER damage can occur via (1) or (2), where (2) is defined as (3). SER damage may also occur through accumulation of (4) leading to (5).
1- direct toxins 2- latent toxins 3- activated by ER, causing damage via release of free radicals 4- misfolded proteins 5- apoptosis
describe how mitochondria cell damage can occur
-usually due to an agent that affects oxidative phosphorylation
- hypoxia, hypoglycemia
- free radicals
- poisons / toxins
describe how lysosome cell damage can occur
1) activation of enzymes => autophagy; digestion of cell components, cells die via necrosis
2) incomplete degradation of phagocytosed material
list some causes of cell injury due to damage to nucleus/nucleolus
- radiation, viruses, chemotherapy
- or ROS => mutations, or if severe enough -> death
hypoxia and ischemia lead to decreased O2 to cell which leads to decreased (1) production, yielding the following three key effects: (2), (3), (4)
1- ATP
2- dec Na/K ATPase pump
3- inc anaerobic glycolysis => dec pH (inc lactic acid)
4- dec protein synthesis (due to detachment of ribosomes)
dec pH in the cell as a result of hypoxia or ischemia results in….
clumping of nuclear chromatin (+ changes in activities of proteins / enzymes)
describe how dec Na/K ATPase pump activity affects the cell
-inc influx of Ca2+, Na+, H2O (follows Na+)
-inc efflux of K+
=> ER swelling and cellular swelling –> loss of microvilli + more blebs
dec Na/K pump activity leads to inc influx of Ca2+ into the cell, resulting in…..
Excessive Intracellular Ca2+ –> activation of cellular enzymes:
- phospholipases –> membrane damage (phospholipid loss)
- proteases –> disrupts membrane and cytoskeletal proteins –> membrane damage
- endonucleases –> nuclear damage
- ATPase –> dec ATP
protection from free radicals include…
(antioxidants)
- catalase
- glutathione
ROS can be produced by the following…..
- chemical and radiation injury
- ischemia-reperfusion injury
- cellular aging
- during microbial killing by phagocytes
list the pathological effects of ROS on cells (hint- 3)
- lipid peroxidation => membrane damage
- protein modifications => breakdown or misfolding
- DNA damage => mutations
describe toxic effect of CCL4
(indirect toxin)
CCL4 –> CCL3 by P450 in hepatocytes => lipid peroxidation
compare cell damage by chemicals or toxins that are direct or indirect
- Direct: binds protein and cell membranes
- Indirect: converted to toxic metabolite (usually in heptocytes) that produce free radicals
list some causes of cell damage via viruses
- rapid replication w/in cell => immune response, inflammation, cell lysis
- cytopathic effects related to specific cell receptors
- effects cytoskeleton => multi-nucleation,and inclusion bodies