Cell Injury & Death Flashcards
Can cell injury be either reversible or irreversible?
yes
What is the first morphologic change in reversible injury?
cellular swelling
In reversible injury, what is derived from damaged ER?
- blebs (distorted plasma membrane)
- early chromatin clumping
- cytoplasmic vacuoles
What can reversible injury be noted as?
increased turgor, pallor, and weight
What can lead to dysfunctional cell membrane transport in reversible injury?
decrease in ATP
Reversible injury results in an influx of what?
water and Na+ that appear as cell swelling
In reversible injury, decreased oxidative phosphorylation promotes what?
glycolysis
Anaerobic respiration leads to what?
lactic acid accumulation and reduced intracellular pH
What are the consequences of the glycolytic pathway?
- altered enzyme function
- decreased protein synthesis
- protein structure and folding
Reduced protein synthesis is refleted in what from the RER?
detachment of ribosomes
The time scale of injury vaties upon what?
the metabolic status of cells
In irreversible injury, why are the membranes weaker?
rupture of lysosomes and autolysis
What is the main difference between reversible and irreversible injury?
lysosomes are damaged in irreversible injury and intact in reversible
What are the 3 nuclear changes in irreversible injury?
karyolysis, pyknosis, and karyorrhexis
What is karyolysis?
progressive disruption and random digestion of nucleus fades away
What is pyknosis?
chromatin becomes densely clumped appearing hard, dark, and shrunken
What is karyorrhexis?
when pyknotic nuclei break up into smaller, dense structures
What are the clinical diagnoses of irreversible injury??
- AST & ALT
- CK & troponin from myocardial cells
- lipase and amylase from pancreas
What are the 2 major forms of cell death?
necrosis and apoptosis
What is necrosis characterized by?
- cell swelling
- protein denaturation
- organelle breakdown
When does necrosis occur?
after loss of blood/oxygen supply or exposure to noxious chemical toxin
What is apoptosis?
programmed cell death
What is apoptosis characterized by?
cell shrinkage, but intact organelles
When does the formaton of DNA fragmentation ladder occur?
during apoptosis
What type of cell injury has intrinsic and extrinsic pathways with no inflammation?
apoptosis
What are the normal physiological processes?
- embryogenesis
- hormone-dependent involution in adult organs
- hoemstasis
What are the pathological processes?
- injury
- viral diseases
- pathologic atrophy in organs after duct obstruction
- immunologic reactions
What is the process of intrinsic apoptosis?
- release of cytochrome-c initiates formation of apoptosome
- Apaf-1 binds cytochrome-c and recruits pro-caspase-9 to apoptosome
- caspase 9 is activated and cleaves other caspases -> apoptosis
What is the difference between intrinsic and extrinsic apoptosis?
- intrinsic= damage to cell
- extrinsic= involves ligand
What are the anti-apoptotic proteins?
BCI-2 and livin
What are the inhibitor/propoptotic proteins?
- XIAP
- c-IAP-1
- c-IAP-2
- survivin
- bax, bid, bad
What is Fas?
membrane spanning protein
What does microscopically apoptosis appear as?
apoptotic bodies
Biochemically/molecularly apoptosis appears as what?
DNA fragmentation ladder
How does intact DNA, apoptotic DNA, and necrotic DNA appear?
- intact: sits at the top
- apoptotic: ladder
- necrotic: big mush
What are the morphologic changes of apoptosis?
- organelles remain intact
- cell shrinks
- blebs form on cell surface
- nuclear fragmentation
- little or no infllamatory reaction
- single cell
Does apoptosis have inflammation?
no
What is the mitochondrial (intrinsic) pathway?
- growth factor withdrawal
- DNA damage
- protein misfolding
What is the death receptor (extrinsic) pathway?
includes receptor-ligand interactions (Fas and TNF receptor)
What is the most common form of cell death?
necrosis
What is necrosis?
- hypoxia, toxins
- involves areas of tissue
What are the morphologic changes that happen to the cell during necrosis?
- cell swells
- organelles are disrupted
- multiple cells
What are the nuclear changes in necrosis?
karyolysis, pyknosis, karyorrhexis
Is there inflammation in necrosis?
yes
What are the 2 types of necrosis?
coagulative and liquefactive
What is coagulative necrosis?
protein denaturation
What is liquefactive necrosis?
enzymatic digestion
What is the most common form of necrosis?
coagulative
Denaturation of cellular proteins causes what?
inhibition of proteolytic enzymes
In what type of necrosis is the architecture reserved?
coagulative
What is the characteristic of hypoxic death?
myocardial infarction
How is proteolysis blocked?
denaturation of proteins and enzymatic proteins
What is gangrene?
type of coagulation necrosis that is the gradual ischemia of distal extremities (foot, leg)
When can gangrene occur?
with diabetes or frostbite
What is the difference between “wet” and “dry” gangrene?
- wet: bacterial superinfection of necrotic material
- dry: black-brown, mummified appearance
What is the difference between coagulative and liquefactive necrosis?
- coagulative: inhibition of indogenous protease enzymes
- liquefactive: enzymes that destroy tissue
What is liquefactive necrosis?
digetsion of cells and tissue due to proteolytic activity with loss of structure
What are the subtypes of liquefactive necrosis?
caseous and fat
What is caseous necrosis?
necrosis due to myobacterial and fungal infections
What is the appearance of caseous necrosis?
cheesy, white
When does fat necrosis occur?
following pancreatic injury and realease of pancreatic enzymes
Lipase digests triglycerides of adjacent what?
adipocytes release of fatty acids
What do fatty acids combine with to form soaps?
extracellular Ca+
What is the appearance of fat necrosis?
chalky white
What are the stimuli resulting in cell injury?
- oxygen deprivation
- chemical and physical agents
- infectious agents
- immunologic reactions
- genetic defects
- nutritional imbalances
- aging
What are the biochemical mechanisms affected in injury?
- depletion of ATP
- generation of reactive O2 species
- defects in membrane permeability
- increased intracellular/loss of Ca
- mitochondrial damage
Proteolysis during ischemia produces what oxidase?
xanthine
Xanthine oxidase can act on purines to produce what?
uric acid & superoxide anion
How is the CCl3 radical formed?
when CCl4 is acted upon by P450 oxidases
How is a free radical injury prevented?
- cellular antioxidant (vitamins E&A)
- sequestration of molecules
- intracellular enzymes
What is Carpal tunnel syndrome?
compression of median nerve
What is Tarsal tunnel syndrome?
compression of tibial nerve
What is Variant tarsal tunnel syndrome?
compression of deep peroneal nerve
In the case study, what was wrong with the ballet dancer?
- bilateral anterior tarsal tunnel syndrome variant
- extensor hallucis bervis muscle hypertrophy