Cell Injury, Death & Adaptation Flashcards
4 mechanisms of adaptation to reversible injury / stress
Hypertrophy, Hyperplasia, Atrophy, Metaplasia
Cellular injury resulting from decreased oxygen
Ischemia
5 mechanisms of cell damage
Oxidative stress
Membrane damage
Mitochondrial damage
DNA damage
Disturbance of calcium homeostasis
Molecule with unpaired electron in outer orbit
Highly reactive
Free radical
Highly reactive molecules which contain oxygen atoms
Reactive oxygen species
ROS are produced normally during these 2 processes
Cellular respiration
Leukocytes during inflammation (respiratory burst)
During the red-ox reactions of mitochondrial respiration, sequential reduction of O2 to H2O2 can result in the occasional “lost” electron, which can form this
Superoxide
Lost e- is added to oxygen to form O2-
Enzyme that forms superoxide radical from oxygen atom
Phagocyte/NADPH oxidase
Enzyme that forms hydrogen peroxide from superoxide radical
Superoxide dismutase
Enzyme that forms hypochlorite from hydrogen peroxide
Myeloperoxidase
What is the Fenton reaction?
Hydrogen peroxide is converted to OH- (hydroxyl) in the presence of Fe2+
Hydrogen peroxide is converted to hydroxyl OH- in the presence of this
Transition metals (Cu and Fe)
ROS damage cells in these 3 ways
Membrane lipid oxidation
Protein oxidation
DNA damage
4 mechanisms of membrane damage
Oxidative stress
Decreased phospholipid synthesis
Increased phospholipid degradation
Cytoskeletal abnormalities
2 ions whose cytosolic levels increase during membrane damage
Ca2+ and Na+
Increased phospholipid degradation may occur when phosphatases are activated by increase cytosolic levels of this
Calcium
Mitochondrial membrane damage can result in these 4 things
Loss of compartmentalization (mitochondrial dysfunction)
Decreased ATP generation
Pro-apoptotic state
Generation of free radicals
Lysosome membrane damage can result in these 2 things
Autolysis and/or necrosis
Glycolytic and citric acid cycle enzymes are found in this part of the mitochondria
Core
Respiratory chain enzymes are found in this part of the mitochondria
Inner membrane
ATP generation occurs in this part of the mitochondria
Intermembrane space
Porin proteins selectively permit small molecules to pass and are found in this part of the mitochondria
Outer membrane
Increased cytosolic calcium leads to this
Enzyme activation
Phospholipidases cause membrane damage
Proteases degrade structural proteins and others
2 mechanisms of mitochondrial damage
Increased cytosolic calcium leads to enzyme activation (phospholipidases, proteases)
Lack of oxygen results in ROS
ATP depletion as a result of mitochondrial damage leads to apoptosis or necrosis?
Necrosis
ATP depletion as a result of mitochondrial damage has these 3 effects
Inability to run Na/K ATPase (increased cytosolic Na, increased H2O)
Decreased oxidative phosphorylation (increased glycolysis, increased lactic acid, protein dysfunction)
Ribosome detachment from rER
Decreased oxidative phosphorylation as a result of mitochondrial damage leads to this
Increased glycolysis, increased lactic acid, protein dysfunction
Leakage of mitochondrial proteins like cytochrome C during mitochondria damage leads to this
Apoptosis
Leakage of cytochrome C into cytosol signals cell damage, and activates this
Caspase enzyme pathway
(DNase activation, protease activation, programmed cell death)
This activates the caspase enzyme pathway during mitochondrial damage
Leakage of cytochrome C into cytosol
Incomplete oxidative phosphorylation during mitochondrial damage produces these
Free radicals
DNA damage is often repaired with this pathway
p53 pathway
During the p53 pathway of DNA damage repair, the cell cycle is arrested in this phase
G1
What happens if the p53 pathway of DNA damage repair is unsuccesful?
Apoptosis occurs; mediated through bcl-2/Bax/Bak pathway
Are normal cytosolic levels of calcium high or low?
Very low due to pumps and membranes
Disturbance of calcium homeostasis has these 2 effects
Influx into mitochondria (swelling, decreased ATP generation)
Inappropriate enzyme activation (endonucleases, proteases, phospholipases, ATPase)
3 intracellular accumulations that are signs of damage/degeneration
Water, Fat, Lipofuscin
2 extracellular accumulations that are signs of damage/degeneration
Hyaline material, Calcium deposition
Accumulation of intracellular lipid
Sign of reversible injury
Occurs mostly in cells involved in lipid metabolism (liver)
Steatosis
Lipid is _______ so it does not dissolve in cytoplasm
Hydrophobic
Excess lipid is morphologically seen as these
Droplets
What produces vacuolization of cytoplasm?
Excess lipid, which is hydrophobic and does not dissolve in cytoplasm, so instead is seen as droplets
Golden-brown intracellular indigestible material made of lipid and protein
“Wear and tear” pigment
Gradually accumulates as cells age
Mostly seen in post-mitotic cells (liver, heart, neurons)
Lipofuscin
What is lipofuscin?
Golden-brown intracellular indigestible material made of lipid and protein
Lipofuscin is mostly seen in this type of cell
Post-mitotic cells (liver, heart, neurons)
Any material that appears dense, amorphous, and intensely eosinophilic
Also intracellular amorphous pink deposits
Hyaline
Vascular hyaline may be due to long-term ______
Hypertension
What is hyaline?
Any material that appears dense, amorphous, and intensely eosinophilic
Damaged proteins deposited in the kidney glomerulus in diabetes
Hyaline
Calcium deposits may form in these two pathological categories
Dystrophic calcification
Metastatic calcification