What types of tissues can ONLY undergo hypertrophy and NOT hyperplasia?
Right Ans - Permanent tissues
- Cardiac muscle
- Skeletal muscle
- Nerve
- This is because they lack stem cells
What are two different pathways to decrease cell size? Right Ans - 1.
Ubiquitin-proteosome degradation pathway
- Intermediate filaments of the cytoskeleton are tagged with ubiquitin and
destroyed by proteosomes
2. Autophagy of cellular components
- Generation of autophagic vacuoles
- These vacuoles fuse with lysosomes whose hydrolytic enzymes breakdown
cellular components
How does vitamin A deficiency lead to metaplasia? Right Ans - - Vitamin A
is necessary for differentiation of specialized epithelial surfaces (i.e.
conjunctiva of the eye)
- If deficient, goblet cells/columnar cells of conjunctiva undergo metaplasia
into keratinizing squamous epithelium
- Dry eyes can lead to destruction of the cornea and blindness
What is Budd Chiari syndrome? Right Ans - Thrombosis of the hepatic vein
- Blocking hepatic vein --> blood can NO longer flow through the liver
- MCC: Polycythemia vera
What are 4 causes of hypoxemia? Right Ans - 1. High altitude = Decreased
barometric pressure
2. Diffusion defect = Thicker diffusion barrier
3. Hypoventilation = Increased PACO2
4. V/Q mismatch = Blood bypasses oxygenated lung or oxygenated air cannot
reach blood
What is methemoglobinemia? Right Ans - - Iron in heme is oxidized to Fe3+
(cannot bind oxygen)
- "Fe2 binds O2"
,- Seen with oxidant stress or in newborns
- Classic finding is cyanosis with chocolate-colored blood
- Tx: Methylene blue
What are signs of reversible cell injury? Right Ans - Cellular swelling
- Can see decreased protein synthesis also
- Loss of microvilli and blabbing
- Swelling of rER results in dissociation of ribosomes and decreased protein
synthesis
What are signs of irreversible cell injury? Right Ans - Membrane damage
- Plasma membrane damage - cytosolic enzymes leak into serum, Ca enters
the cell
- Mitochondrial membrane damage - Loss of electron transport chain,
cytochrome c leaking into cytosol
- Lysosome membrane damage - hydrolytic enzymes leaking into the cytosol
What is the morphologic hallmark of cell death? Right Ans - Loss of the
nucleus
- Occurs via:
1. Nuclear condensation (pyknosis)
2. Fragmentation (karyorrhexis)
3. Dissolution (karyolysis)
What tissues exhibit coagulative necrosis? Right Ans - Any tissue type
besides the brain
- Area of infarction is wedge-shaped
- Remains firm
- Cell shape and organ structure are preserved by coagulation of proteins
What tissues exhibit liquefactive necrosis? Right Ans - All tissues, including
brain tissues
- Necrotic tissues become liquefied
- Enzymatic lysis of cells and protein results in liquefaction
Where do you usually see gangrenous necrosis? Right Ans - Lower limbs
GI tract
,With what types of infections do you see caseous necrosis? Right Ans - TB
Fungal
What is saponification? Right Ans - - An example of dystrophic calcification
- Calcium deposits on dead tissues
- Necrotic tissue acts as a nidus for calcification in the setting of normal serum
calcium and phosphate
Function of proteases? Endonucleases? Right Ans - Proteases: Break down
the cytoskeleton
Endonucleases: Break down DNA
What are the 3 pathways for caspase activation (leading to apoptosis)?
Right Ans - 1. Intrinsic mitochondrial pathway
- Inactivation of Bcl2
- Lack of Bcl2 allows cytochrome c to leak out from the inner mitochondrial
matrix into cytoplasm
2. Extrinsic-ligand pathway
- FAS ligand binds FAS death receptor (CD95) on target cell OR
- TNF binds TNF receptor on the target cell
3. Cytotoxic CD8+ T-cell mediated pathway
- Perforins secreted by CD8+ cells create pores in membrane of target cell
- Granzyme from CD8+ cell enters pores and activates caspases
What deposits in primary amyloidosis? Secondary amyloidosis? Right Ans -
Primary: AL, derived from immunoglobulin light chain
Secondary: AA, derived from serum amyloid-associated protein
What is fibrinoid necrosis? Right Ans - Necrotic damage to blood vessel
wall
- Leaking of proteins (including fibrin) into vessel wall
- Results in bright pink staining of the wall
- Characteristic of malignant hypertension and vasculitis
What are the two general causes of acute inflammation? Right Ans - 1.
Infection
, - Neutrophils come in
- To eliminate pathogen
2. Tissue necrosis
- To clear necrotic debris so healing can begin
- Is followed by acute inflammation
- Repair phase of wound healing
Characteristics of Toll Like Receptors? Right Ans - - Present on cells of the
innate immunity
- Activated by PAMPs that are commonly shared by microbes
- CD14 on macrophages recognizes LPS on the outer membrane of Gram-
bacteria
- TLR activation results in up regulation of NF-kappaB (nuclear transcription
factor) that activates immune response genes leading to the production of
immune mediators
- Also present on cells of adaptive immunity
What are the 4 mediators of neutrophils? Right Ans - 1. LT4 (leuokotriene
4)
2. C5a
3. IL-8
4. Bacterial products
What 3 things activate macrophages? Right Ans - 1. Tissue trauma
2. Complement proteins C3a and C5a
3. Cross-linking of cell-surface IgE by antigen
What are the 3 activation pathways for complement? Right Ans - 1.
Classical pathway - C1 binds to IgG or IgM bound to antigen
2. Alternative pathway - Microbial products directly activate complement
3. Mannose-binding lectin pathway - MBL binds to mannose on
microorganisms and activates complement
What is Hageman factor? Right Ans - Factor XII
- Activated upon exposure to sub endothelial or tissue collagen
- Activates
1. Coagulation and fibrinolytic systems
2. Complement
3. Kinin system
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