Pathology Principles Flashcards
What to look for in Gross Examination
- The organ
- Size
- Shape
- Consistency
- Color
What to look for in light Microscopic Examination (H and E)
- Hematoxylin: blue or purple (Nuclei, Bacteria and Calcium) [NBC]
- Eosin: pink or red (Proteins)
What to look for in light Microscopic Examination (Periodic Acid-Schiff [PAS])
Carbohydrates in the following conditions:
- DM
- Glycogen storage diseases
- Alpha-1 antitrypsin deficiency
- Fungi
- Whipple disease
- AML-M6
- Paget’s disease
Causes of Cellular Injury
- Hypoxia
- Infection
- Immunologic reactions
- Congenital disorders
- Chemical injury
- Physical injury
- Nutritional or vitamin imbalance
What are the critical intracellular systems that are susceptible to injury
- DNA
- ATP production (mitochondria)
- Cell membranes
- Protein synthesis
Important mechanisms of cell injury
- Oxygen free radicals (superoxide anion [O2’-], hydroxyl radical [OH’], and hydrogen peroxide [H2O2])
- ATP depletion
- Increased cell membrane permeability
- Influx of Calcium (uncontrolled)
- Release of cytochrome c from mitochondria which triggers apoptosis
Protective Factors against free radicals
- Anti-oxidants (vitamins A, C, E and Selenium)
- Certain metal carrier proteins like transferrin and ceruloplasmin
- Superoxide dismutase (superoxide —> hydrogen peroxide)
- Glutathione peroxidase (hydroxyl ions or hydrogen peroxide —-> water)
- Catalase (hydrogen peroxide —-> oxygen and water)
Reversible changes in cellular injury due to decreased oxidative phosphorylation
- Cell swelling due to decreased Na+/K+ ATPase pump which results in influx of Na+ and efflux of K+
- Decreased pH due to increased glycolysis and increased lactic acid
- Decreased protein synthesis due to ribosomal detachment
Irreversible changes in cellular injury due to decreased oxidative phosphorylation
Severe membrane damage which results in influx of Ca++ and leak of cytoplasmic enzymes out of the cell
Cardiac Markers
- Troponin I
- CK-MB
- LDH (means there something died)
- Myoglobin
- AST
Liver Markers
ALT > AST (except in alcoholic hepatitis in which AST > ALT)
Pancreas Markers
- Amylase (sensitive)
- Lipase (specific)
Biliary tract obstruction markers
First do Alkaline Phosphatase if +ve (which is +ve in bone disease too) then do GGT
Coagulative Necrosis
- Due to ischemia
- Dry gangrene
- Micros. loss of nucleus but preservation of cellular shape
- Proteins denature then enzymatic degradation
- Most organs including heart, liver and kidney
Liquefaction Necrosis
- Cellular destruction by hydrolytic enzymes
- Wet gangrene
- Enzymatic degradation then proteins denature
- Abscess, brain infarcts and pancreatic necrosis
Caseous Necrosis
- Combination of coagulation and liquefaction
- Gross. soft, friable, cottage-cheese like
- Micros. granuloma with peripheral giant cells
- TB and Fungi
Fibrinoid Necrosis
- Due to acute immunologic injury (hypersensitivity reaction type II and III) and malignant hypertension
- Micros. eosinophilic (pink) homogeneous appearance
Fat Necrosis
- Gross. chalky white appearance
- Micros. fat cells without peripheral nuclei. saponification of fat (combined with calcium) appears dark blue on H and E stain
- Damaged cells release lipase which breaks down triglycerides in fat cells
- Either enzymatic like acute pancreatitis or non-enzymatic like trauma to the breast
Apoptosis (Definition and morphologic appearance )
- Programmed cell death without inflammatory response
- It involves a single cell or a small groups of cells
- Cells shrink and has dense eosinophilic cytoplasm then fragmentation of the nucleus
- DNA laddering (fragments in multiples of 180 bp) is a sensitive indicator of apoptosis
Cellular Adaptive Responses to Injury
- Atrophy
- Hypertrophy
- Hyperplasia
- Metaplasia
- Dysplasia
Inflammation Hemodynamic Changes
- Initial transient vasoconstriction
- Massive vasodilatation mediated by Histamine, bradykinin, and prostaglandins
- Increased vascular permeability by Histamine and Serotonin (platelets), bradykinin, and leukotrienes (LTC4, LTD4, LTE4)
- Blood stasis due to increased viscosity, allows neutrophils to marginate
Neutrophils Primary (azurophilic) granules content
- Myeloperoxidase
- Phospholipase A2
- Lysozyme (hydrolysis of 1,4-beta-linkages in bacterial walls)
- Elastase
- Defensins (microbicidal peptides)
- Bacterial permeability increasing protein (BPI)
Neutrophils Secondary (specific) granules content
- Phospholipase A2
- Lysozyme
- Leukocyte alkaline phosphatase (LAP)
- Collagenase
- Lactoferrin (chelates iron)
- Vitamin B12 binding proteins
Macrophages enzyme content
- Acid hydrolases
- Elastase
- Collagenase
Selectins in Neutrophil migration and adhesion
- Weak binding
- Initiate rolling
- P-selectins and E-selectins on endothelial cells bind Sialyl-Lewis X and PSGL-1 on leukocytes
- GlyCam-1/CD34 on endothelial cells bind L-selectins on leukocytes
Integrins in Neutrophil migration and adhesion
- Stable binding with adhesion
- ICAM-1 (CD54) on endothelial cells binds LFA-1 and MAC-1 (CD11/18) on leukocytes
- VCAM-1 (CD106) on endothelial cells binds VLA-4 on leukocytes
Defects in neutrophil adhesion (Conditions)
- DM
- Corticosteroid use
- Acute alcohol intoxication
- Leukocyte adhesion deficiency (AR disease)
Leukocytes Emigration (diapedesis)
- Post-capillary venule
- Dissolve the basement membrane via collagenase (type 4 metaloprotease [zinc dependent])
- PECAM-1 (CD31) on endothelial cells and leukocytes
Neutrophils Chemotactic factors
- N-formyl-methionine
- Leukotriene B4 (LTB4)
- Complement system product C5a
- IL-8
Factors that modulate the expression of adhesion molecules in inflammation
- Histamine
- Thrombin
- TNF-alpha
- IL-1
Important Opsonins
- Fc portion of IgG
- Complement system product C3b
- Plasma protein such as collectins (which bind to bacterial cell walls)
Defects in Phagocytosis
Chediak-Higashi syndrome (AR, neutrophils have giant granules, albinism, LYST gene)
Deficiency of Oxygen-dependent killing
- Chronic granulomatous disease (X-linked or AR) with NADPH oxidase deficiency
- Myeloperoxidase deficiency (AR) a condition characterized by infections with candida
- Nitroblue Tetrazolium Reduction test (+ve is purple-blue and means there is enzyme so normal [no disease])
Histamine (Production, Function, and Triggers)
- Produced by basophils, platelets, and mast cells
- Vasodilation and increased vascular permeability.
- Triggers are IgE-mediated mast cell reactions, physical injury, anaphylotoxins (C3a and C5a), and cytokines (IL-1)
Serotonin (Production and Function)
- Produced by platelets
- Vasodilation and increased vascular permeability.
Kinin system (First and end products, and Function)
- Activated Hageman factor (factor XII) and Bradykinin
- Vasodilation, increased vascular permeability, bronchoconstriction and pain
Arachidonic acid products (Cyclooxygenase pathway)
- Thromboxane A2 produced by platelets and causes vasoconstriction and platelet aggregation
- Prostacyclin (PGI2) produced by vascular endothelial cells and cause vasodilation and inhibition of platelet aggregation
- Prostaglandin E2 causes pain
- Prostaglandins PGE2, PGD2, and PGF2 cause vasodilation
Arachidonic acid products (Lipoxygenase pathway)
- Leukotriene B4 (LTB4) causes neutrophil chemotaxis
- Leukotrienes C4, D4, E4 cause vasoconstriction
Mediators of Pain
- Bradykinin
- Prostaglandin E2