Step 1 First Aid - Pathology Flashcards
USMLE Step 1 First Aid - Pathology notes (190 cards)
Apoptosis is characterized by…?
Cell shrinkage, nuclear shrinkage and basophilia (pyknosis), membrane blebbing, pyknotic nuclear fragmentation (karyorrhexis), nuclear fading (karyolysis), and formation of apoptotic bodies, which are then phagocytosed. No significant inflammation.
Apoptosis (definition)
Programmed cell death; ATP required. Mediated by caspases.
When does apoptosis occur?
Occurs during embryogenesis, hormone induction (menstruation), immune cell-mediated death, injurious stimuli (e.g., radiation, hypoxia), atrophy (e.g., endometrial lining during menopause)
Necrosis (definition)
Enzymatic degradation of a cell resulting from exogenous injury.
Necrosis is characterized by…?
Enzymatic digestion and protein denaturation, with release of intracellular components. Inflammatory.
Necrosis morphologies
Coagulative (heart, liver, kidney) Liquefactive (brain) Caseous (tuberculosis) Fat (pancreas) Fibrinoid (blood vessels) Gangrenous (limbs, GI tract)
Characteristics of reversible cell injury
Cellular swelling Nuclear chromatin clumping Decr ATP synthesis Ribosomal detachment Glycogen depletion Fatty change
Characteristics of irreversible cell injury
Plasma membrane damage Lysosomal rupture Ca2+ influx –< oxidative phosphorylation Nuclear pyknosis, karyolysis, karyorrhexis Mitochondrial permeability
5 Characteristic signs of inflammation
Rubor (redness) Dolor (pain) Calor (heat) Tumor (swelling) Functio laesa (loss of fxn)
Fluid exudation in inflammation
Incr vascular permeability, vasodilation, endothelial injury.
Leukocyte activation in inflammation
Emigration (rolling, tight binding, diapedesis); chemotaxis (bacterial products, complement, cytokines); phagocytosis and killing.
Substances that are chemotactic for neutrophils
IL-8 C5a Leukotriene B4 Kallikrein
Fibrosis in inflammation
Fibroblast emigration and proliferation; deposition of ECM.
Acute inflammation
Neutrophil, eosinophil, and Ab-mediated. Rapid onset (seconds-minutes), lasts minutes-days.
Chronic inflammation
Mononuclear cell mediated: Characterized by persistent destruction and repair. Associated w/ blood vessel proliferation, fibrosis. Granuloma – nodular collections of epithelioid macrophages and giant cells.
Granulomatous dz’s
TB (caseating) Syphilis Listeria monocytogenes Wegener’s granulomatosis Leprosy Bartonella Some fungal pneumonias Sarcoidosis Crohn’s dz *Granuloma formation is IL-2, interferon-gamma mediated.
Resolution of inflammation
Restoration of normal structure. Granulation tissue – highly vascularized, fibrotic. Abscess – fibrosis surrounding pus. Fistula – abnormal communication. Scarring – collagen deposition resulting in altered structure and fxn.
Characteristics of trans udate
Hypocellular Protein-poor Specific gravity > 1.012 Due to: Incr hydrostatic pressure Decr oncotic pressure Na+ retention
Characteristics of ex udate
Cellular Protein-rich Specific gravity < 1.020 Due to: Lymphatic obstruction Inflammation
Leukocyte extravasation
Neutrophils exit from blood vessels at sites of injury and inflammation in 4 steps: 1.) Rolling 2.) Tight binding 3.) Diapedesis 4.) Migration <img></img>
Rolling (step 1 in leukocyte extravasation)
Mediated by E-selectin and P-selectin on vascular endothelium binding to sialyl Lewis^x on the leukocyte. <img></img>
Tight binding (step 2 of leukocyte extravasation)
Mediated by ICAM -1 on vascular endothelium binding to LFA-1 (integrin) on the leukocyte (“Hold on tight to your CAM era”) <img></img>
Diapedesis (step 3 in leukocyte extravasation)
Leukocyte travels btw endothelial cells and exits blood vessel; PECAM-1 is involved. <img></img>
Migration (step 4 in leukocyte extravasation)
Leukocyte travels thru the interstitium to the site of injury or infxn guided by chemotactic signals (e.g., cytokines) <img></img>