Random Facts from Uworld Flashcards
Common Clinical Disinfectants
Alcohol- disrupts cell membranes, denatures proteins, not sporicidal
Chlorhexidine- disruption of cell membranes, coagulation of cytoplasm, not sporicidal
Hydrogen peroxide- free radicals, sproricidal
Iodine- halogenation of proteins and nucleic acids, sporicidal
Bezold-Jarisch reflex
receptors in atria, great veins, and ventricle that cause vagal-mediated bradycardia and hypopnea secondary to underfilling or ischemia
Cricothyrotomy (indications, procedure, anatomy)
- laryngeal edema (emergency airway)
- punctures through skin, superficial cervical fascia, investing deep fascia, pretrachial fascia, cricothyroid membrane
- Reference figure in ‘Neck 14-15’ lecture
Platelet Deficiencies
Hereditary defects of platelet function
Syndrome
Defect
Bernard-Soulier Syndrome
GP Ib/IX (vWF Receptor)
Glanzmann’s Thrombasthenia
GP IIb/IIIa Complex
d-Storage Pool Disease
Dense Body Deficiency
a-Storage Pool Disease (Gray Platelet Syndrome)
Alpha Granule Deficiency
Scott Syndrome
Decreased platelet surface acidic phospholipid expression
Quebec Syndrome
Multimerin defect; a-granule and procoagulant activity defect
Stimulus-response coupling defects
Heterogeneous; defects of cyclooxygenase, G-couple proteins or calcium response
Platelet Physiology
Endothelial damage–> subendothelial collagen with vWF binds to GP Ib-IX-V receptors on platelets–> activated plates change chape and release granules –> platelet releases ADP and produces TxA2–> platelet receptor GPIIBIIIA binds fibrinogen for aggregation
Anti-platelet Pharmacotherapy
- Clopidgrel, Prasugrel, Ticlopidine, nucleosides (P2Y12 ADP receptor activation antagonist)
- NSAIDS, Asprin (inhibit TxA2 synthesis and secretion)
- Dipyridamole (decrease platelet cAMP levels)
- inhibit GPIIaIIIb receptors (Abciximab, tirofiban, eptifibatide)
Mechanism of orthostatic hypotension in pregnancy
Supine/right lateral decubitis position–> compression of IVC–> decrease venous return–> decreased preload–> decreased cardiac output–>hypotension; predominantly in women >20 weeks gestation
Carcinoid Tumor (Description, Serotonin Syndrome)
- chromogranin positive low-grade malignancy of neuroendocrine cells commonly found in the small bowel as a submucosal polyp-like nodule
- secretes serotonin
- if tumor metastasizes to liver, tumor-secreted serotonin bypasses MAO-mediated conversion to 5’HIAA and enters to hepatic vein to be distributed systemically to the right heart, skin, lungs etc.
- MAO found in lungs, serotonin in the right heart causes fibrosis and valvular pathology
- Symptoms: skin flushing, abdominal cramping, n&v, diarrhea
Pathological Changes in Brain Injury
- acute injury produces eosinophilic neuronal necrosis, shrinkage of cell body, pyknosis of the nucleus, loss of nissl substance (red neuron)
- subacute injury and chronic injury produces cell loss and reactive gliosis (hypertrophy/plasia of astrocytes)
- axonal injury produces chromatolysis (swelling with eccentric displacement of nucleus to periphery)
- neurodegenerative disease causes neurofibrillary tangles and Lewy bodies (abnormally phosphorylated tau)
Progression of Stroke (Gross)
negligible (< 2 days)–> edema, pallor, blurred gray-white junction (2-10 days)–> liquefactive necrosis + cavitation (>10 days)
Progression of Stroke (microscopic)
red neurons (12-14 hours)–> PMNs (24-48 horus)–> lipid-laden macrophages (3-5 days)–> coagulative necrosis–> liquefactive necrosis–> remote infarct (CSF-filled glial (astrocyte) lined space)
Osteomyelitis (mechanisms of spread)
- hematogenous seeding due to an episode of bacteremia
- spread from a contiguous focus of infection, as occurs in an infected diabetic foot wound
- direct inoculation of bone, such as with a compound fracture
Osteomyelitis (Situation/Causative Organism/Mechanism of Spread/Site of pathology)
Childhood age/staph aureus/hematogenous seeding/long bones
Sickle cell/hematogenous/salmonella+s.aureus/long bones
Pott/hematogenous/mycobacterium TB/vertebrae
Diabetes mellitus/contiguous spread from infected foot ulcer/pseudomonas aeruginosa+serratia/bones of the feet
Recumbent patients with impaired motility/contiguous spread from pressure sores/polymicrobial/sacrum+heels
Prosthetic joint replacement/direct inoculation/s. aureus+ s. epidermis/prostheses
Mechansism of Lactic Acidosis
- Imparied gluconeogenesis/glycogenolysis
- increased metabolic rate (seizures/exercise)
- decreased oxygen delivery (hypoperfusion)
- decreased oxygen use (cyanide toxicity)
- diminished lactate catabolism due to hepatic failure
Prepatellar bursa (Anatomy, function, pathology)
- located between patella and overlying skin adn prepatellar tendon, lined by synovium and very little fluid
- diminsishes friction and ensures maximal range of motion in knee
- bursitis presents as knee pain, swelling, redness, and inability to flex
- may be secondary to chronic kneeling
Vascular Derivatives of the Aortic (Branchial) Arches
- First (part of the maxillary artery)
- Second (hyoid artery, stapedial artery)
- Third (common carotid artery, proximal internal carotid artery)
- Fourth (aortic arch on the left, proximal right subclavian artery on the right)
- Sixth (Ductus arteriosus on the left, proximal pulmonary arteries)
Composition of blood from the pulmonary veins
- Fully oxygenated blood from the pulmonary capillaries
- Deoxygenated blood from the bronchial veins (a minority of the bronchial blood supply drains to the right heart via azygous/hemiazygous/intercostal veins)
Lofgren Syndrome
- acute sarcoidosis
- hilar lymphadenopathy
- erythema nodosum
- arthritis
- fever
Keratin (composition)
- made of ALA and GLY, which are small AA’s that allow for coiling and multiple H-bond formation
- made of cysteine, dimerization to cystine confers stability
Amino Acid Derivatives
- Arg–> NO
- Arg+Asp–> urea
- Gly+succinyl CoA–> heme
- Gly+Arg+SAM–> Creatinine
- Glu–> GABA
- Glu–> Glutathione
- Glu+Asp–> Pyrimidines
- Glu+Asp+Gly–> Purines
- Histadine–> Histamine
- Phe–> tyrosine–> DOPA–> Dopamine
- Try–> 5HT–> Melatonin
- Try–> Niacin
- Tyr–> Thyroxine, Melanin
Mech. of Vasodilation
Ach/bradykinin/5HT/substance P/sheer forces–> Ca influx–> endothelial nitric oxide synthase–> NO–> GC–>cAMP–> reduction of Ca influx–> smooth muscle relaxation
Rate of diffusion across a semipermeable membrane
{Delta P (molecular concentration difference across the membrane)*Surface Area*Solubility of the Substance]/[Thickness*Molecular Weight]
Cheyne-Stokes Respiration
- cycles of apnea and increased tidal volume breathing
- seen in advanced CHF and neurological injury (brain tumor, stroke)
Serous vs Mucous
- Serous is water secretion of enzymes
- Mucous is glycoprotein mixture
- Serous glands have basophilic cytoplasm with centrally located nucleus
- Mucous glands have empty cytoplasm with densely stained basal nuclei
- Sublingual glands are mucous
- Submandibular glands are mixed
- Parotid glands are serous
