Growth Adaptations, Cell Injury and Cell Death Flashcards
describe the mechanisms of cell injury and how it affects the organelles
describe why hypoxia causes cellular injury
- low O2 delivery to tissue; important cause of cellular injury
- O2 is the final electron acceptor in the ETC of oxidative phosphorylation
- decreased O2 impairs oxidative phosphorylation, resulting in decreased ATP production
- lack of ATP (essential energy source) leads to cellular injury
low ___ disrupts key cellular functions, including: ____
low ATP disrupts key cellular functions, including:
- Na/K pump, resulting in sodium and water buildup in the cell
- Ca2+ pump, resulting in Ca2+ buildup in the cytosol of the cell
- switch to anaerobic glycolysis
- lactic acid buildup results in low pH which denatures proteins and precipitates DNA
the initial phase of injury is ____; the hallmark of ____ injury is ____
explain this concept
the initial phase of injury is reversible; the hallmark of reversible injury is cellular swelling
- cytosol swelling results in loss of microvilli and membrane blebbing
- swelling of the rER results in dissociation of ribosomes and decreased protein synthesis
- blebs, myelin figures (cell memb.), mt swelling
the hallmark of irreversible injury is _____
explain examples of this in the cell
the hallmark of irreversible injury is membrane damage
-
plasma membrane damage results in:
- cytosolic enzymes leaking into the serum (cardiac troponin)
- additional Ca2+ entering into the cell
-
mitochondrial membrane damage results in:
- loss of the ETC (inner mt membrane)
- cytochrome c leaking into cytosol (activates apoptosis)
- lysosome membrane damage results in hydrolytic enzymes leaking into the cytosol, which, in turn, are activated by the high intracellular Ca2+
describe what is seen in the image
describe what is seen in the image
describe injury to the nucleus
describe injury to the lysosomes
describe injury to mitochondria
list reversible ischemic injury events
- impaired aerobic respiration (mt)
- decreased ATP (energy)
- anaerobic glycolysis
- glycogen depletion
- lactic acidosis and nuclear chromatin clumping
list the sequence of events in reversible injury
the critical point of cellular injury is the inability of ___ to recover
the critical point of cellular injury is the inability of mitochondria to recover
list the sequence of events for an irreversible injury
describe injury by free radicals and explain what most free radicals do
most affect cell membranes producing energy loss
- the most common = activated oxygen radicals (aging, chemical, x-rays, infxns, inflammation, tumors, etc.)
- free radicals affect cell membranes by lipid peroxidation and affect nucleic acids with mutations
- protective mechanisms (antioxidants) = catalase, glutathione
give an example of direct effect of chemicals on cells
- direct = Hg (mercury) binds to proteins and cell membranes
describe coagulative necrosis
most common type of necrosis
- necrotic tissue that remains firm
- cell shape and organ structure are preserved by coagulation of cellular proteins
- nucleus disappears
- acidophilic mass (since nucleus no longer stains basophilic)
- characteristic of ischemic infarction of any organ except brain
describe liquefactive necrosis and name the 3 situations it is seen in
- necrotic tissue becomes liquified
- enzymatic lysis by hydrolytic enzymes of cells and proteins results in liquefaction
- characteristic of:
- brain infarction
- abscess (bacterial infxns)
- pancreatitis
describe fat necrosis
- necrotic adipose tissue with chalky-white appearance due to deposition of calcium
- in fat, release of lipases from dead pancreatic cells –> FFA + Ca2+ = saponification
- example of dystrophic calcification
describe gangrenous necrosis
- coagulative necrosis that resembles mummified tissue (dry gangrene)
- characteristic of ischemia of lower limb and GI tract
- if superimposed infection occurs, then liquefactive necrosis ensues (wet gangrene)
describe caseous necrosis
- soft, friable necrotic tissue with “cottage cheese-like” appearance
- eosinophilic
- combination of coagulative + liquefactive necrosis
- characteristic of granulomatous inflammation due to TB or fungal infection
describe fibrinoid necrosis
- necrotic damage to blood vessel wall
- leaking of proteins into vessel wall results in bright pink staining
- characteristic of malignant hypertension or vasculitis
describe intracellular accumulations
- fatty change = accumulation of lipids
- accumulation of proteins = Ig (Russell bodies)
- accumulation of glycogen = storage disorders, diabetes
- mixtures of lipids and carbohydrates = mucopolysaccharides
describe how free radicals cause damage
- peroxidation of lipids
- oxidation of DNA and proteins
- DNA damage is implicated in aging and oncogenesis
