Pathology Flashcards
What is the definition of apoptosis?
Programmed cell death
Does apoptosis require ATP?
Yes
Describe how apoptosis occurs.
Intrinsic and Extrinsic pathways: both pathways –> activation of cytosolic camases that mediate cellular breakdown.
Is there inflammation involved in apoptosis?
No. (unlike necrosis)
Apoptosis is characterized by deeply _________ cytoplasm.
Eosinophilic
What is pyknosis?
Nuclear shrinkage seen in apoptosis
What is karyorrhexis?
nuclear fragmentation seen in apoptosis
What types of cells increase drastically during apoptosis?
basophils
Name one sensitive indicator of apoptosis
DNA laddering
Describe DNA laddering.
During karyorhexis, endonucleases cleave at internucleosomal regions, yielding 180-bp fragments.
When do we see the intrinsic pathway for apoptosis used?
Involved in tissue remodelling in embryogenesis
When does the intrinsic pathways of apoptosis initiate?
Occurs when a regulating factor is withdrawn from a proliferating cell population (e.g IL-2 after a completed immunological reaction –> apoptosis of proliferating effector cells).
Also occurs after exposure to injurious stimuli (e.g radiation, toxins, hypoxia)
Changes in pro-apoptotic factors lead to…
increase in mitochondrial permeability and cytochrome c release
Name 2 pro-apoptotic proteins.
BAX and BAK
Name an anti-apoptotic protein.
Bcl-2
How does Bcl-2 prevent apoptosis?
Bcl-2 prevents cytochrome c release by binding to and inhibiting Apaf-1. Apaf-1 normally activates capsases.
Bcl-2 is over expressed (e.g. follicular lymphoma) then…
…Apaf-1 is overly inhibited, leading to decrease caspase activation and tumorigenesis.
Where are BAX and Bcl-2 found in the cell?
mitochondria
Where are cytochrome c found in the cell?
mitochondria
Describe the two pathways of the extrinsic apoptosis
- Ligand receptor interactions (FasL binding to Fas [CD95])
2. Immune cell (cytotoxic T-cell release of perforin and granzyme)
Fas-FasL interaction if necessary in _______________ selection
thymic medullary negative selection
What do mutations in Fas do?
increase the number of circulating self-reacting lymphocytes due to failure of colonial deletion
After Fas cross links with FasL…
multiple Fas molecules coalesce, forming a binding site for a death domain - containing adapter protein, FADD.
What does FADD do?
FADD binds inactive caspases, activating them.
What is the basis for autoimmune disease?
Defective Fas-FasL interaction
List the 6 types of necrosis
- Coagulative
- Liquefactive
- Caseous
- Fatty
- Fibrinoid
- Gangrenous
Where does coagulative necrosis occur?
Heart, liver, kidney (in tissues supplied by end-arteries)
Where does liquifactive necrosis occur?
Barin, bacterial abscess, occurs in CNS due to high fat content
How does coagulative necrosis progress?
increased cytoplasmic binding of acidophilic dye. Proteins denature first, followed by enzymatic degradation
How does liqifactive necrosis progress?
In contrast to coagulative necrosis, enzymatic degradation due to the release of lysosomal enzymes occurs first
What pathogens result in caseous necrosis?
TB, systemic fungi, Nocardia
What types of fatty necrosis exist?
Enzymatic - pancreatitis [saponification]
Non-enzymatic - Breast Trauma
What dis-eases lead to fibrinoid necrosis?
Vasculitides (e.g. Henoch-Schonlein purpura, Churg-Strauss syndrome)
Malignant hypertension
What types of gangrenous necrosis exist?
Dry (ischemic coagulative)
Wet (infection)
Where are gangrenous necrosis common?
Limbs and GI tract
List some processes that cause cell injury that are reversible (O2 is still present)
ATP depletion
Cellular mitochondrial swelling (decreased ATP –> decreased activity of Na+/K+ pumps)
Nuclear chromatin clumping
Decreased glycogen
Fatty change
Ribosocomal/polysomal detachment (decreased protein syn)
Membrane blebbing
List some processes that cause cell injury that are irreversible.
Nuclear pyknosis
karyorrhexis
karyolysis
Plasma membrane damage (degradation of membrane phospholipid)
Lysosomal rupture
Mitochondrial permeability/vacuolization; phospholipid-containing amorphous densities with mitochondria (swelling along is reversible)
What area if susceptible to hypoxia/ischemia and infarction in the brain?
ACA/MCA/PCA boundary area (watershed areas (border zones) receive dual blood supply from most distal branches of 2 arteries, which protects these areas from single-vessel focal blockage. However, these ares are susceptible to schema from systemic hypo perfusion)
What area if susceptible to hypoxia/ischemia and infarction in the Heart?
Subendocardium (LV)
What area if susceptible to hypoxia/ischemia and infarction in the Kidney?
Straight segment of proximal tubule (medulla)
Thick ascending limb (medulla)
What area if susceptible to hypoxia/ischemia and infarction in the Liver?
Area around the central vein (zone 3)
What area if susceptible to hypoxia/ischemia and infarction in the Colon?
Splenic flexure, rectum
What areas of the brain does hypoxic ischemic encephalopathy (HIE) affect?
Pyramidal cells of the hippocampus and Purkinje cells of the cerebellum
When/Where do red infarcts arise?
Occur in loose tissue with multiple blood supplies, such as liver, lung, and intestines. Red = reperfusion
When/Where do pale infarcts arise?
Occur in solid tissues with a single blood supply, such as heart, kidney, and spleen.
What is the first sign of shock?
Tachycardia
What types of shock are included under the umber ally term: distributive shock?
Includes: septic, neurogenic and anaphylactic shock
What characterizes distributive shock?
High output failure (decreased TPR, increased CO, increased venous return)
Decreased PCWP
Vasodilation (warm skin)
Failure to increase blood pressure with IV fluids
What characterizes hypovolemic/cardiogenic shock?
Low output failure (increased TPR, decreased CO, increased venous return) PCWP increases in cardiogenic PCWP decreases in hypovolemic Vasoconstriction (cold, clammy patient) Blood pressure restored with IV fluids
What cells mediate acute inflammation?
Neutrophils, eosinophils, antibodies
What cells mediate chronic inflammation?
Mononuclear cells and fibroblasts
Define Granuloma
nodular collection of epithelioid macrophages and giant cells. Outcomes include scarring and amyloidosis.
Define Chromatolysis
Increase in protein synthesis in an effort to repair the damaged axon following axonal injury.
What characterizes chromatolysis?
Round cellular swelling
Displacement of the nucleus to the periphery
Dispersion of Nissl substances through cytoplasm
What is dystrophic calcification?
Calcium deposition in tissue secondary to necrosis (usually localized).
In ______ calcification, patients are generally normocalcemic
In ______ calcification, patients are generally NOT normocalcemic
Dystrophic calcification = normocalcemic
Metastatic calcification = NOT normocalcemic
Define Matastatic Calcification
Widespread deposition of Ca+ in normal tissue secondary to hypercalcemia or higher Ca+/P product
What is the interaction between pH levels and Calcium deposition?
Increased pH (basic) = higher calcium deposition Decreased pH (acidic) = less calcium deposition
Where does leukocyte extraversion predominantly occur?
postcapillary venules
What are the 4 steps of Leukocyte extraversion?
- Margination and rolling
- Tight binding
- Diapedesis - leukocyte travels between endothelial cells and exits blood vessels
- Migration - leukocyte travels throug interstitium to site of injury or infection guided by chemotactic signals
REVIEW THIS PROCESS - First Aid, Pg. 224
How do free radicals damage cells?
membrane lipid peroxidation
protei modification
DNA breakage
How do we end up with free radical injury?
Radiation exposure metabolism of drugs (phase 1) redox reactions nitric oxide transition metals leukocyte oxidative burst
How can free radicals be eliminated?
Enzymes, spontaneous decay, antioxidants (Vit. a,c,e)
Following an injury to skin, what % of tensile strength can a patient expect to regain and how long will it take
70-80% of pre-injury tensile strength
in 3 months
Describe the differences between hypertrophic scars and keloid scars in terms of collagen synthesis
Collagen synthesis increases in hypertrophic scars but increases MORE in keloids
Describe the differences between hypertrophic scars and keloid scars in terms of collagen arrangement
Keloid scars = disorganized collagen
Hypertrophic scares = parallel scars
Describe the differences between hypertrophic scars and keloid scars in terms of extent of scaring
Keloid - extend beyond the borders of the original scar
Hypertrophic scars - confined to the border of the original wound
Describe the differences between hypertrophic scars and keloid scars in terms of recurrence
Keloid - frequently require following resection
Hypertrophic scars - infrequently recur following resection
What is the role of PDGF in wound healing?
secreted by activated platelets and macrophages
Induces vascular remodeling and smooth muscle cell migration
Stimulated fibroblast growth for collagen synthesis
What is the role of FGF in wound healing?
Stimulated all aspect of angiogenesis
What is the role of EGF in wound healing?
Stimulated cell growth via tyrosine kinases (e.g. EGFR, as expressed by ERBB2)
What is the role of TGF-B in wound healing/
Angiogenesis, fibrosis, cell cycle arrest
What is the role of metalloproteinases in wound healing?
Tissue remodeling
What cells are immediate/inflammatory cell markers of wound healing?
Platelets, neutrophils, macrophages
What are the characteristic findings of an area with lots of platelets, neutrophils and macrophages present during wound healing?
clot formation, increased vessel permeability and neutrophil migration into tissue; macrophages clear debris 2 days later
What are the characteristic findings of an area with lots of fibroblasts, myofibroblasts, endothelial cells, keratinocytes, macrophages during wound healing?
Depositionof granulation tissue and collagen, angiogenesis, epithelial cell proliferation, dissolution of clot, and wound contraction (mediated by myofibroblasts)
What cells are present during the proliferative phase (2-3 days after wound)?
Firboblasts, myofibroblasts, endothelial cells, keratinocytes, macrophages
What cells are present in the 3rd and final phase of wound healing - remodelling (1 week after the wound)?
Fibroblasts
What are the characteristic finding of an area with lots of fibroblasts present after a wound occurs?
Type 3 collagen replaced by type 1 collagen.
Increase in tensile strength of tissue.
What is it that induces and maintains granuloma formation?
TNF-a
List some diseases that are granulomatous
Bartonella henselae (cat scratch disease) Berylliosis Churg-Strauss syndrome Crohn's Francisella tularensis Fingal infections Granulomatosis w/ polyangiitis (Wegener) Listeria monocutogenes (granulomatosis infantiseptica) M. leprae M. tuberculosis Treponema pallidum (teritary syph) Sarcoidosis Schistosomiasis
Transudate/Exudate - which is thick and which is thin
Exudate - thick
Transudate - thin
Exudate is protein ___
Transudate is protein ___
Exude - protein rich
transudate - protein poor
Exudate specific gravity _____
Transudate specific gravity ____
Exudate SG = >1.020
Transudate SG = <1.020