USMLE Step 1 Exam With Complete
Solution
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 comprehension
-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
Solution
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 comprehension
-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
