USMLE Step 1 Exam 2022/2023 with complete solutions

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Heterophile ab NEGATIVE Mono-like syndromes - ANSWER *CMV HHV-6 HIV Toxoplasmosis Wernicke's Aphasia - ANSWER -word salad: well-articulated, nonsensical speech paired with lack of lang comprehen... sion -aud association cortex: post part of sup temporal gyrus - supplied by MCA Congenital Deficiency of Propionyl CoA Carboxylase - ANSWER -prevents conversion of propionyl CoA to methylmalonyl CoA -propionyl CoA derived from= val, ile, met, thr, odd # FA, cholesterol side chains -Propionic Acidemia: poor feeding, vomiting, hypotonia, lethargy, dehydration, anion gap acidosis Down Synd Comorbidities - ANSWER Neuro: MR, early onset Alzheimer's Cardio: complete AV septal defect, VSD, ASD GI: duodenal atresia, hirschprung disease Endo: hypothyroid, DM1, obesity Heme: ALL (> 5 yo) and AML (<5 yo) Rheumatology: atlantoaxial stability MCC of Hypoglycemia in EtOH-ics - ANSWER Thiamine def= suppression of GNG (pyruvate DH) and TCA cyle (alpha-KG DH) MCC of Hypoglycemia in advanced renal insuff - ANSWER impaired clearance of insulin Avoid Nitrates in Hypertrophic Cardiomyopathy bc... - ANSWER Nitrates decrease preload, which will increase the LV outflow tract... BUT since the ventricle is abnormally shaped, there is an outflow obstruction Mets through BM - ANSWER Clonal proliferation of cells can invade/ metastasize* 1. malignant cells to lose their cell-to-cell adhesion molecules (cadherins) 2. cell receptors to attach to laminin (a glycoprotein) in the basement membrane and to release metalloproteinases (e.g., collagenases, stromelysins, gelatinases) to degrade the basement membrane and other enzymes to degrade the interstitial connective tissue- tissue inhibitors of metalloproteinases neutralize these tumor-produced enzymes and limit the degree of invasion 3. cell receptors to attach to bronectin and other proteins in the extracellular matrix (ECM) and to break it down 4. malignant cells to produce cytokines that stimulate locomotion, so that they can move through basement membranes and the intracellular and extracellular matrices Bicuspid Aortic Valve - ANSWER Commonly presents in young, asymptomatic patient with soft systolic ejection at right 2nd ICS -can cause aortic regurg MCC of Vaginal Candidiasis - ANSWER 1. Abx use= reduces lactobacilli pop 2. High estrogen levels- preg 3. System corticosteroid therapy 4. Uncontrolled DM 5. Immunosuppression, including HIV Drug causes of SIADH - ANSWER -Carbamazepine -Cyclophosphamide -SSRI MC Ankle Sprain due to inversion of plantar-flexed foot - ANSWER -Ant Talofibular Lig dmg -ecchymosis at the ant-lat aspect of the ankle Upper Brachial Plexus Injury - ANSWER - Musculocutaneous and Suprascapular N. - dystocia mc in neonates; severe trauma mc in adults - should adduction, elbow extension, and forearm pronation Patent foramen ovale - ANSWER -failure of septum primum and septum secundum to fuse after birth -can lead to paradoxical emboli Ventricular Septal Defect - ANSWER -MC occurs in membranous septum -Acyanotic at birth bc of L to R shunt Coronary Blood Flow Peak - ANSWER -at Early Diastole -coronary perfusion driven by diastolic pressure -tachycardia will decrease coronary perfusion Right Dom Heart - ANSWER majority of people -PDA comes off RCA -SA and AV nodes supplied by RCA Left Dom Heart - ANSWER -PDA comes off of LCX - SA and AV node supplied by LCX Increased Pulse Pressure - ANSWER hyperthyroidism, aortic regurgitation, aortic stiffening (isolated systolic hypertension in elderly), obstructive sleep apnea ( sympathetic tone), exercise (transient) Decreased Pulse Pressure - ANSWER aortic stenosis, cardiogenic shock, cardiac tamponade, advanced heart failure (HF) Causes of Spontaneous Depol causing Tachyarrhythmias - ANSWER Hypokalemia, Hypermagnesemia, or prolonged QT interval = all cause spontaneous depol of ventricles in phase 3 or 4 and it will cause an extra AP in heart Direct alpha 1 agonist mediated effects - ANSWER - vasc smooth muscle contraction= increased afterload and venous return= increased DBP + SBP causes reflexive increase in vagal tone= dec HR and slowed AV conduction - mydriasis - increased internal urethral sphincter tone and prostate contraction Direct alpha 2 agonist mediated effects - ANSWER - CNS med decrease in BP - decreased intraocular pressure - decreased lipolysis - decreased presyn NE release - increased platelet aggregation S. epidermidis - ANSWER - coag neg -novobiocin sens - infective endocarditis and infective arthritis in prosthetic pts Asymptomatic heart defect in turner's synd - ANSWER -nonstenotic bicuspid aortic valve -early systolic , high frequency click over right second IC space Cardiac Changes w/ Normal Aging - ANSWER - decreased left ventricular chamber size - shortened base- to- apex dimension - ventricular septum becomes sigmoid and shape, with basilar portion bulging into LV outflow tract - atrophy of myocardium causes increased interstitial connective tissue, often with concomitant extracellular amyloid deposition - lipofucin pigment accumulation within cardiomyocytes ARDS - ANSWER Characterized by the development of hypoxemia and bilateral pulmonary infiltrates in the absence of heart failure -begins with initial injury of pul alveoli (smoke inhal) or pul endothelium (sepsis) which leads to the recruitment of neutrophils- this worsens the situation and leads to intraalveolar accumulation and hyaline membrane formation -decreased lung compliance, increased work of breathing, worsened V/Q mismatch, and normal PCWP Renal Artery Stenosis (histo) - ANSWER medial fibroplasia, absent internal elastic lamina in areas of aneurysmal dilation Paget's Disease associate Bone Tm - ANSWER OSTEOSARCOMA! arising from tibia, femur, humerus, and other bones -pain doesnt resolve with OTC analgesics DNA Laddering (Gel Electrophoresis) - ANSWER - DNA fragments in multiples of 180 bp each - sensitive indicator of APOPTOSIS - laddering done by specific endonucleases during haryorrhexis, cleaving DNA at interucleosomal linker regions - this is not seen in cancer cells, since they evade apoptosis Warburg Effect - ANSWER malignant cells undergo high rates of glycolysis to produce macromolecules necessary to sustain rapid cellular growth Risk Factors of Endometritis - ANSWER -C-section delivery -chorioamnionitis -group B strep colonization -intrauterine instrumentation -preterm delivery -prolonged labor -prolonged ruptured membranes -retained products of conception SIGNS AND SX OF POSTPARTUM ENDOMETRITIS -fever -leukocytosis -uterine tenderness -foul smelling vaginal discharge Metabolic derangements assoc with DKA - ANSWER metabolic acidosis, ketonemia, hyperglycemia, hyperkalemia, hyponatremia -hyperammonemia can be observed due to muscle degradation Pulmonary Embolism - ANSWER V/Q Mismatch, causes hypoxemia that increases ventilation and HR via a chemoreceptor reflex -hypocapnia b/c hypervent, but unable to compensate for hypoxemia -resp alkylosis= increased ph and decreased PaCO2 Acanthosis Nigracans - ANSWER -Obesity/ insulin resistance -Malignancy of GI or Lungs Congenital Pyloric Stenosis - ANSWER -thickening of stomach wall, hypertrophy of smooth muscle pyloric stenosis -palpable olive mass- epigastric region -nonbilious projectile vomiting at 2-6 weeks of age -assoc w/ Macrolides -hypokalemia, hypochloremic, metab alkalosis Vomiting - ANSWER powerfully stimulates metabolic alkalosis through direct loss of Hþ, loss of Cl , and volume depletion Chronic diarrhea - ANSWER may cause a metabolic alkalosis because of volume contraction Respiratory compensation for metabolic alkalosis - ANSWER hypoventilatory capacity limited owing to resulting hypoxemia Mineralocorticoid excess - ANSWER think volume expansion, hypertension, hypokalemia, hypernatremia, metabolic alkalosis Essential tremor - ANSWER -worsens when maintaining particular postures -improve/ subside with etoh -tx: propranolol -AD inheritance= Familial tremor Serotonin Synd - ANSWER confusion, agitation,tremor, tachycardia, htn, clonus, hyperreflexia, hyperthermia, diaphoresis TX: Cyproheptadine= 1st gen histamine antag, nonspec 5-HT1 and 5-HT2 rec antag Tensilon Test - ANSWER -Cholinergic Crisis: muscles stop responding to the bombardment of ACh, leading to flaccid paralysis, respiratory failure, and other signs and symptoms reminiscent of organophosphate poisoning. Other symptoms include increased sweating, salivation, bronchial secretions along with miosis.-- Flaccid paralysis resulting from cholinergic crisis can be distinguished from myasthenia gravis by the use of the drug edrophonium (Tensilon), which worsens the paralysis caused by cholinergic crisis, but strengthens the muscle in the case of myasthenia gravis. (Edrophonium is an cholinesterase inhibitor hence increases the concentration of acetylcholine present). under-tx'd MG pt presents with exaggerated MG sx, and when infused with edrophonium the sx subside it indicates that the MG treatment (AChE inhib) need to increase in dose Opioid action on mu rec - ANSWER -g-protein coupled activation of K+ efflux= hyperpol and pain transmission termination -inhib adenylyl cyclase -inhib Ca2+ conductance -inhib transmitter release neonatal intravascular hemorrhage - ANSWER -mc in fragile germinal matrix -inc freq with decreased age and birth wt -mc complication would be long term neurodev impairment (alt consciousness, hypotonia, dec spont mvmnt) -s/sx of bleed: bulging ant frontanelle, hypotension, decerebrate posturing, tonic-clonic seizures, irreg respirations, coma Acute Rheumatic fever - ANSWER -endemic in dev countries -molecular mimicry: anti group a strep ab attack host antigens on cardiac and neuronal tissue approx 2-4 weeks post acute pharyngitis (aka cross reactivity of ab against bacterial and host antigens) -acute/subacute: migratory arthritis, pancarditis, Sydenham chorea -Chr: mitral regurg/ stenosis -tx: PCN Spironolactone + HF - ANSWER improve survival of CHF pts with low LV ejection fraction -block aldosterone's effect on heart and decrease fibrosis and ventricular remodeling -used with ace-inhib and beta-blockers Common S/E of Thiazide Diuretics - ANSWER acute kidney injury, decreased Na+ and K+, hyperuricemia/ acute gout, elevated glu and cholesterol levels Common S/E of ACE-Inhib - ANSWER cough, angioedema, inc K+ CCB (diphenhydropine) S/E - ANSWER periph edema, dizziness/ lightheadedness Beta Blocker S/E - ANSWER bronchospasm, bradycardia, fatigue, sexual dysfunction HTN and at risk for Osteoporosis - ANSWER THIAZIDES! increased bone mineral density b/c increase in Ca2+ abs in DCT Methylmalonyl-CoA mutase Def - ANSWER -AR -increased urine: methylmalonic acid and propionic acid -hyperammonemia, ketotic hypoglycemia, and metab acidosis -newborns present with lethargy, vomiting, and tachypnea TCA Effect on Cardiac Na+ Channel - ANSWER BLOCKS cardiac fast Na+ channels= QT and QRS prolongation and arrhythmias -treated with Sodium Bicarb MC Complication post Subarachnoid Hemorrhage - ANSWER SAH sx: thunderclap ha, confusion, fever, nuchal rigidity MC Compl: VASOSPASM! -vessels surrounding ruptured aneurysm -cerebral ischemia and new onset confusion and/or focal neuro deficits (paresthesia, weakness, etc) 4-12 days post SAH -mech of vasospasm is related to impaired brain autoreg -not seen on CT, need transcranial color doppler -Nimodipine prescribed to prevent vasospasm post-SAH Most Serious Compl of SAH - ANSWER REBLEED! -sudden dev of severe confusion, HA, N/V, decreased consciousness, focal neuro deficits -seen on CT t(8;14) - ANSWER Burkitt lymphoma (c-myc activation) -cmyc is an oncogene -very aggressive, rapid proliferation of cell growth t(9;22) aka Philadelphia chromosome - ANSWER CML (BCR-ABL hybrid), rarely ALL -constitutive expression of tyrosine kinase -poor prognosis when expressed in ALL t(11;14) - ANSWER Mantle cell lymphoma (cyclin D1 activation) -cyclin D1 is a cell cycle regulator -this translocation continuously allows cells to go on in cell cycle without stopping/ apoptosis t(14;18) - ANSWER Follicular lymphoma (BCL-2 activation) [Diffuse Large B-Cell Lymphoma] -bcl-2 inhibits apoptosis normally -in this CA, there is constant anti-apoptotic activity t(15;17) - ANSWER APL (M3 type of AML) -translocation of retinoic acid rec (chr 15) onto chr 17, blocks maturation and abnormal pro-myelocytes/ blasts increase which can lead to an increase in DIC t(12;21) - ANSWER Acute lymphoblastic leukemia/lymphoma *better prog Inc RBC, WBC and Platelets - ANSWER polycythemia= increase hematocrit Decreased EPO - ANSWER -Polycythemia Vera (neg feedback) -Anemia of Chr Disease -Chr Kidney Disease Corticosteroids cause ... - ANSWER -Neutrophilia, despite causing eosinopenia and lymphopenia -Corticosteroids activation of neutrophil adhesion molecules, impairing migration out of the vasculature to sites of in ammation - BUT, sequester eosinophils in lymph nodes and cause apoptosis of lymphocytes Neutropenia - ANSWER Sepsis/postinfection, drugs (including chemotherapy), aplastic anemia, SLE, radiation Lymphopenia - ANSWER HIV, DiGeorge syndrome, SCID, SLE, corticosteroids, radiation, sepsis, postoperative Eosinopenia - ANSWER Cushing syndrome, corticosteroids MM - ANSWER - Inc susceptibility to infection - Primary amyloidosis (AL) - Punched-out lytic bone lesions on x-ray = activated RANK-L increased osteoclast activity - M spike on serum protein electrophoresis - Ig light chains in urine (Bence Jones protein) - Activated IgG prod by plasma cells by IL-6, may lead to proteasome inhib - Rouleaux formation (RBCs stacked like poker chips in blood smear) CO Poisoning - ANSWER Normal PO2 (dissolved O2) Decreased %sat of Hb Decreased total O2 content = makes Fe2+ into Fe3+(ferric), leading to the formation of met [Show More]

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