USMLE Step1 Resp PhysioPath

serutihe's version from 2016-12-01 18:38


Question Answer
Surfactant is AKAlecithin, dipalmitoyl phosphatidylcholine
extension of ciliated cellsupper airways to terminal bronchioles.
goblet cellssecrete mucin. extends to bronchi
Type 1 pneumocyte97% of alveoli. thin squamous.
Type 2 pneumocytesurfactant. proliferate during damage -> type 1
clara cellsnon cilliated. secrete component of surfactant. degrade toxin.
Measure of fetal lung maturitylecithin - sphingomyelin ratio >2
lingulahomologue to middle lobe. on left lung
aspirate peanut upright vs supineupright -> lower right inferior lobe, supine -> superior right inferior lobe
pulmonary artery to bronchus location on L and R lungsRALS. Right anterior and Left Superior.
diaphragm innervationC3, 4, 5, keeps the D alive
structures piercing diaphragmI (IVC) ate (8) ten eggs (esophagus) at (aorta) 12.
muscles for stressed inspirationdiaphragm, ext intercost, scalene, sternomastoid
muscles for stressed expirationrectus/transverse abdominus, int/ext oblique, int intercost
neonatal respiratory distress syndromelack of surfactant
lung chemical productssurfactant, prostaglandin, histamine, ACE, kallikrein
kallikreinactivates bradykinin
bradykinininhibited by ACE, activated by kallikrein. cause cough, angioedema, vasodilation
collapsing pressureP = 2(Surface Tension)/radius. tendency to collapse on expiration
Lung volumesResi - left over, expir reserve - normal exp to max, tidal - normal, inspir reserve - normal insp to max, vital - max to min, inspir capacity - min normal to max insp. func reserve - min normal to all left in lung
dead spacetaco (paco-peco) /paco. VT is tidal volume. paco = arterial CO2, peco = expired air CO2
compliancechange in volume for given change in pressure
Hemoglobin R vs TT is taut. R is relaxed and better O2 carrying.
Fetal Hb vs adultFetal higher affinity
MethemoglobinFe3+ instead of Fe2+. inc affinity for CN. can be cured by methylene blue
Cyanide poisoning Txnitrates to induce metHb, binds CN, add thiosulfate, makes thiocyanate -> renal excretion
Carboxyhemoglobinbinds CO in place of O2 (200x affinity)
what shifts Hb curve right?CBEAT. CO2, BPG, Exercise, Acid/Altitude, Temperature.
perfusion vs diffusion limitedperfusion limited by blood flow. diffusion limited by thickening of wall
Diffusion lung formuladiffusion = (Area/Thickness) x Difference in partial pressure
Pulm Art. pressuresnormal 10-14. > 25 is HTN, or 35 during exercise.
Primary pulm HTNinactivated BMPR2. proliferation of smooth muscle. poor prognosis
secondary pulm HTNingestion of appetite suppressent Fenphen. COPD, mitral stenosis, recurrent thomboemboli, autoimmune, left right shunt. sleep apnea/high altitude
1g Hb binds # O2?1.34 mL.
cyanosis at what # deoxygenate Hb?> 5g/dL out of 15 (33%)
Alveolar gas equationPAO2 = 150-Paco/0.8
A-a gradientincreases when there is shunting, V/Q mismatch, fibrosis.
where is vent and perf greatest?base of lung
when does V/Q approach 1 for apex?exercise. opens capill
Carbonic anhydrase MoACO2 + H2O <-> H2CO3.
Haldane effectdiss of H+ from Hb shifts towards formation of CO2 and release in lungs
Altitude responseinc ventilation -> inc Hb -> inc BPG -> Inc excretion of bicarb -> RVH
Embolus typesFATBAT. fat, air, thrombus, bacteria, amniotic fluid, tumor
lines of zahnindicate formation before death
Homan's signtender gastronemous with dorsiflexion of foot
COPDchronic bronchitis, emphysema, asthma, bronchiectasis
Chronic bronchitis pathBlue bloaters, hypertrophy of mucus secreting glands in bronchioles. Reid index. fibrosis, metaplasia. Affects small airways
Reid indexgland depth / total thickness of bronchial wall. COPD > 50%
Dx/Sx of chronic bronchitisproduct cough >3mos/yr or > 2 years. Wheezes, crackles, cyanosis (early), dyspnea (late)
Emphysema pathpink puffer. barrel chest. increased compliance. Elastase activity increased.
Dx/Sx of Emphysemapursed lips breathing to inc airway pressure and prevent collapse during resp.
asthma pathreversible constriction. SMuscle hyper, curschmann's spiral. Carcot-leyden crystals. eosinopihls. triggered.
Dx/Sx of asthmatest with methacholine challenge. cough, wheeze, tachyp, dyspn, hypoxemia, pulsus paradoxus, mucus plugging
methacholine challengeDx asthma
bronchiectasischronic necrotizing infection of bronchi. permanent dilated airway, purulent sputem, hemoptysis.
Assx of bronchiectasisbhroncial obstruction, poor ciliary motility (smoking), Kartagener's, inc aspergillosis
restrictive lung disease Dxdec lung volumes. FEV1/FVC ratio > 80%
Types of restrictive lung diseasespoor breathing mechanics vs interstitial lung disease
Poor breathing mechanics problemscan be muscular (polio, MG), or structural (scoliosis, obesity)
Interstitial lung diseaseARDS, Neonatal RDS, pneumoconioses (coal/asbestos), sarcoidosis, IPF, goodpasture's, wegener's, eosinophilic granuloma, drugs
sarcoidosis lung effectsbilateral hilar lymphadenopathy. noncaseating granuloma. inc ACE and Calcium
Coal miner's lungscor pulmonale, caplan's syndrome (RheumoArth), upper lobes
Silicosisfoundaries, sandblasting, mines. imapirs phagolysosomes and macrophages -> inc TB rates. Upper lobe. egg shell calcification of hilar lymph nodes.
Asbestosisship building, roofing, plumbing. ivory white plaques. bronchogenic carcinoma /mesothelioma. Lower lobes. Dumbell shaped bodies.
ARDSmany causes. diffuse alveolar damage. intraalveolar hyaline membrane. dec compliance, inc work, dec O2 diffusion, inc water permeability.
Obstructive vs normal vs Restrictive dxnormal FEV/FVC = 80%. obstructive <80%. restrictive
Tracheal deviationstoward site of lesion for bronchial obstruction and spontaneous pneumo, away from lesion in tension pneumo
lung cancer presentationscough, hemoptysis, obstruction, wheezing, coin lesion or non calcified nodule on CT
Complications of lung cancerSPHERE of complications, superior vena cava syndrome, pancoast tumor, horners, endocrine (paraneoplastic), recurrent laryngeal symptoms, Effusions
small cell carcinoma lungscentral location. agressive. ACTH/ADH production. causes LEMs (Ca chnl), Tx is chemo. not surgery..
Kulchinsky cellssmall dark blue cells found in small cell carcinoma.
adenocarcinomamost common in non smokers. prolif or clara and type 2.
Bronchioloalveolar cancernot linked smoking. hypertrophic osteoarthropathy.
Squamous CC in lungshilar mass. Cavitation Smoking. Parathyroid activity. keratin pearls and intercellular bridges
large cell carcinomaperipheral. poor prognosis. moved surgically. pleomorphic giant cells with leukocyte fragments
carcinoid tumorserotonin secretion. carcinoid syndrome. fibrous deposits on RH valves and RHF.
Carcinoid Syndromeflushing, diarrhea, wheezing, salivation. endogenous secretion of secretion and kallikrein by tumor.
mesotheliomamalignancy of pleura. see psammoma bodies.
Pancoast tumorsuper sulcus tumor @ apex of lung will -> cervical sympathetic plexus -> horner's.
hornersptosis, miosis, anhidrosis
Superior vena cava syndrometumor obstruct SVC -> raise ICP -> risk of aneurysm. caused by bronchogenic carcinoma, non hodgkin lymphoma 2nd