Pathology Flashcards
What is the mechanism by wc the lesions are produced?
Pathogenesis
‘HOW’ of dse
What is the increase in cell SIZE that occurs in tissues incapable of cell division?
Hypertrophy
What can be the stimulus for hypertrophy?
Increase in fxnal demand
Increase in hormonal stimulation
Mechanism for hypertrophy
Increase cellular protein production
Hypertrophy examples in physiologic & pathologic
Physiologic: Gravid uterus, muscle of body builders
Pathologic: LVH
What is the increase in NUMBER of cells that occurs in tissues capable of cell division?
Hyperplasia
Stimulus of Hyperplasia
Hormonal or compensatory mechanism
Mechanism of Hyperplasia
- Growth factor driven proliferation of mature cells
- Increase output of new cells from tissue stem
Examples of physiologic and pathologic hyperplasia
Physiologic: pubertal breast changes, liver regeneration
Pathologic: endometrial hyperplasia
What is the decrease in cells SIZE and NUMBER?
Atrophy
Stimulus of Atrophy
- Decrease workload, denervation
- Ischemia
- Malnutrition
- Loss of endocrine stimulation
- Pressure
Mechanism of Atrophy
- Decrease protein synthesis
- Increase protein degradation
- Autophagy
Examples of physiologic and pathologic atrophy
Physiologic: embryonal atrophy (notochord & thyroglossal duct)
Pathologic: senile atrophy of brain
What is a differentiated cell type replaced by another cell type?
Metaplasia
Stimulus and mechanism of metaplasia
Stress that leads to reprogramming of stem cells
Examples of metaplasia
- Columnar to squamous: Vit A deficiency
- Squamous to columnar: Barrett’s esophagus
What happens during atrophy or loss of brain substance?
Narrow gyrus and widen sulci
What is defined as the effect of a variety of stresses d/t etiologic agents a cell encounters, wc result in changes in its internal and external environment?
Cell injury
What causes cell injury?
1) O2 deprivation (hypoxia) and Ischemia
2) Physical agents
3) Chemicals and drugs
4) Infectious/Microbial agents
5) Immunologic
6) Genetic derangements (mutate)
7) Nutritional derangements/imbalances
What are morphologic alterations in reversible cell injury?
Cell swelling (eosinophilic) Fatty change
Ultrastructure changes
- Plasma mem alterations (bleb, blunt, loss microvilli)
- Mitochondrial changes (swell, amorphous densities)
- Dilation of ER (form myelin figures)
- Nuclear alterations (disaggregation of granular & fibrillar)
What are the two processes underlying changes in necrosis?
Denaturation of proteins
Enzymatic digestion
Necrotic cells are more eosinophilic (pink) than
viable cells
What appears “glassy” homogenous, vacuolated cell membranes, fragmented?
Necrotic cell - it is mainly as a result of the loss of glycogen
What are dead cells that may be replaced by large, whorled phospholipid masses?
Myelin figures (seen in reversible injury)
What nuclear change is a small dense nucleus?
Pyknosis
What nuclear change is a faint dissolved nucleus?
Karyolysis
What nuclear change is a fragmented nucleus?
Karyorrhexis
What is the most common tissue pattern of necrosis?
Coagulative necrosis
Protein denaturation with preservation of cell & tissue framework
Coagulative necrosis
A. wedge-shaped kidney infarct (yellow)
B. loss of nuclei and an inflammatory infiltrate
“tombstone” appearance
Coagulative necrosis
Digestion of dead cells, resulting in the transformation of the tissue into a liquid viscous mass (pus)
Liquefactive necrosis
Localized bacterial infection (abscesses) and in the brian
Liquefactive necrosis
Autolysis or heterolysis predominates over protein denaturation
Liquefactive necrosis
What isn’t a pattern of cell death but a term commonly used in clinical practice?
Gangrenous necrosis
What type of gangrene is predominantly coagulative?
Dry gangrene
What type of gangrene is more liquefactive (w abscess)?
Wet gangrene
Tuberculous lesions
Soft, friable, cheese-like
Caseous necrosis
Microscopic: amorphous eosinophilic material w cell debris (fragments of nucleus and inflammatory cells)
Like homogeneous pink substance
Caseous necrosis
In fat necrosis, how does release of FA (wc attract Ca salts)then complex w Ca soaps (saponification) happen?
Lipase activation
What can be seen in pancreatitis?
Fat necrosis
Gross: white chalky areas (fat saponification)
Microscopic: vague cell outlines, Ca deposition
Fat necrosis
Necrosis: Immune rxns involving BV
Fibrinoid necrosis
Brain
Liquefactive
Heart, kidneys
Coagulative
Limb
Gangrenous
TB
Caseous
Vasculitis
Fibrinoid
What is the fundamental cause of necrotic cell death?
ATP depletion
What is the consequence of ischemic & toxic injury?
ATP depletion
In ATP depletion, what will reduced Na pump activity (dt hypoxia) then increase influx of Na, H2O and Ca cause?
Cell swelling
What happens when there is hypoxia?
Increase glycolysis then glycogen depletes, lactic acid increases and there’ll be intracellular acidosis
What is the consequence of increased cytosolic Ca, ROS and O2 deprivation?
Mitochondrial damage
Abn oxidative phosphorylation then formation of ROS leads to necrosis
Mitochondrial damage
What happens when Ischemia/toxins –> Ca influx + release of Ca from mitochondria and ER?
- activates phospholipases –> degrades mem phospholipids (wc inc mem perm that leads to cell swelling or leakage of caspases)
- activates proteases –> brks down mem and cytoske CHONs
- activates ATPases –> ATP depletion
- activates endonucleases –> chromatin fragmentation
What are important mediators of cell injury?
Ca ions
What is the most common type of injury?
Ischemic and hypoxic injury
What happens when there’s mechanical obstruction in the arteries?
Ischemia then reduce venous drainage, compromised delivery of substrates for glycolysis
What are the mechanisms of ischemic cell injury?
Sequence of events:
1Decreased O2 tension
2Loss of oxidative phosphorylation
3Decreasee prodxn of ATP
4Failure of Na pump –> loss of K –> influx of Na and water –> cell swell
5Ca influx
6Progressive glycogen loss, decreased CHON synthesis
What is the death of cells after bld flow resumes and is also associated w neutrophilic infiltration?
Ischemia-reperfusion injury
What are the mechanisms of ischemia-reperfusion injury?
- inc generation of O2-derived free radicals
- resulting inflammation and recruitment of PMNs
- activation of complement
What is the difference between direct and indirect chemical injury?
Direct - bind to critical molecular component
Indirect - conversion to reactive toxic metabolites
Anti-apoptotic
BCL2
BCL-XL
MCL1
Pro-apoptotic
BAX
BAK
Sensors
BAD, BIM, BID, Puma, and Noxa
What is the activation of death receptors on the cell membrane (TNFR1 and Fas) called?
Extrinsic (Death Receptor) Pathway
- caspases 8 & 10
Initiator caspases –> executioner caspases –> nuclear fragmentation; endonuclease activation; brkdwn of cytoskeleton
Execution Phase
What are examples of apoptosis?
Growth factor deprivation DNA damage Protein misfolding TNF family receptors Cytotoxic T lymphocytes
What does necroptosis resemble?
Necrosis morphologically
Apoptosis mechanistically
What is the cause of necroptosis?
TNF and viral proteins
Necroptosis is caspase-independent and it activates
RIP1 and RIP3 (Receptor Interacting Proteins) complexes –> increases ROS and decreases mitochondrial ATP prodxn –> necrosis
What is the most common lipid?
TAGs
Other lipids: CHOL, CHOL esters, phospholipids
What occurs when a normal constituent (tags) accumulates, leading to increase in intracellular lipids?
Steatosis - most common in liver
True or False. Is steatosis reversible?
True. Though it may lead to cirrhosis if in excess.
What is the reabsorption droplets in proximal renal tubules?
Nephrotic syndrome
What is the excess of normally-secreted proteins?
Plasma cells actively producing Igs (Russell Bodies)
Seen in MM
What is the defective intracellular transport and secretion?
a1-antitrypsin deficiency
What is the accumulation of cytoskeletal proteins?
Alzheimer’s dse (neurofibrillary tangles)
What is the aggregation of abn proteins?
Amyloidosis