USMLE UWORLD STEP 1| LATEST QUIZBANK WITH
QUESTIONS AND ANSWERS | LATEST 2024
Nitroglycerin (nitrates) - symptomatic relief in chronic stable angina - MOA? Adverse
effects? - Predominantly a *venodilator*, also some arterial vasodilation - decreases
both preload & afterload (stroke volume maintained) -- NO ^cGMP, decreasing
intracellular Ca, dephosphorylating myosin light-chain, relaxing vascular smooth muscle
-- headaches, flushing, lightheadedness, hypotension, reflex tachycardia ---
nitroprusside can cause cyanide toxicity
First line treatment for essential tremor - Propranolol
RAS signaling protein is active when bound to - GTP (ex: constitutively activated KRAS
implicated in colon cancer)
Mullerian Aplasia - No upper (therefore short) vagina, variable uterine development.
46,XX females with normal ovaries and 2ndary sexual characteristics
Physician's priority in domestic violence case - safety (emergency plan? safe place to
go?) - don't confront denial or pressure patient to disclose abuse or leave
Stroke in what brain area would cause complete contralateral SENSORY loss -
Thalamus
Cause of lacunar infarcts - small vessel occlusion due to lipohyalinosis and
microatheroma formation -> lenticulostriate arteries <- uncontrolled HTN & DM
Cocaine MOA - inhibits presynaptic reuptake of NE,D,S (increased sympathetic
activity); vasoconstrictor (cause MI, sudden death)
Mutations associated with thyroid cancer: medullary vs follicular vs anaplastic -
Medullary (RET), Follicular (RAS), Anaplastic (p53)
Dynein vs Kinesin - molecular motor proteins
(nerve axonal transport direction) - Dynein (periphery->center, + to -, retrograde)
Kinesin (center->periphery, - to +, anterograde)
Negative end Near Nucleus
Positive end Points to Periphery
,Treatment of choice for behavioral symptoms of delirium - low dose antipsychotic
(haloperidol)
Adenosine & Dypyridamole - selective vasodilators of all coronary vessels, can cause
coronary steal syndrome (hypoperfusion & worsening of existing myocardial ischemia)
Treatment of choice for status epilepticus? (single seizure lasting >5 minutes or multiple
discrete seizures with incomplete recovery between episodes) - IV benzodiazepine (like
lorazepam) ...to stop the seizure, then concurrently begin phenytoin to prevent
recurrence
Pellagra - *Vitamin B3 (Niacin) deficiency - diarrhea, dermatitis, dementia* - precursor
for NAD & NADP (cofactors for many dehydrogenase and reductase enzymes) - seen in
those with poor nutrition (alcoholics) or corn-heavy diets - Niacin can be synthesized
endogenously from *tryptophan*
Stimulation of what nerve will move bulky tongue out of the way in obstructive sleep
apnea? - Hypoglossal
Femoral nerve block (location) - Inguinal crease at lateral border of femoral artery -
numbs anterior thigh, quads, femur, knee
Pudendal nerve block (anatomic landmark / location) for delivery? Presentation of
stretch injury? - Ischial spine tip - for vaginal deliveries
Decreased sensation in perineum and genital area; can cause fecal/urinary
incontinence (pudendal normally controls external sphincters) - although, most common
cause of anal incontinence after childbirth is sphincter damage
Gigantism - hypersecretion of growth hormone from AP; changes mediated by release
of: - insulin-like growth factor 1 (IGF-1) from liver
Toxic component of LPS - Lipid A ... gram-negative sepsis
ACE-inhibitor induced angioedema & dry cough is due to? -- ACEi also decrease GFR
and increase potassium - bradykinin accumulation (vasodilator, increases vascular
permeability; also increases prostaglandin production, irritating bronchi) - normally
broken down by ACE
Lateral ankle sprain due to inversion of plantar-flexed foot most commonly involves: -
anterior talofibular ligament
Anticholinergic toxicity - Atropine & scopolamine (in jimsonweed) competitively inhibit
muscarinic Ach receptors. Blind as a bat, mad as a hatter, red as a beet, hot as a hare,
dry as a bone, full as a flash, fast as a fiddle. REVERSED by cholinesterase inhibitors
(physostigmine).
,How does timolol help treat glaucoma? - non-selective beta-blocker diminish secretion
of aqueous humor by ciliary epithelium (decrease IOP) [glaucoma = progressive
peripheral vision loss]
Ebstein anomaly - Displacement of tricuspid valve leaflets downward into RV,
decreased RV volume, atrialization of RV -- caused by *lithium* teratogenicity, treats
bipolar disorder -- tricuspid regurg & right heart failure
Zellweger syndrome - infantile defective peroxisomal biogenesis (very long chain fatty
acids and branched chain fatty acids cannot undergo oxidation) - buildup causes
craniofacial abnormalities, hepatomegaly, neurologic defects, death -- adult version: x-
linked adrenoleukodystrophy
Pulsus paradoxus - Exaggerated drop in systolic blood pressure (>10 mmHg) during
inspiration -- most commonly seen in pericardial effusion with cardiac tamponade
Beck's triad = Cardiac Tamponade - Hypotension with pulsus paradoxus, elevated
jugular venous pressure, muffled heart sounds
Acute intermittent porphyria - Autosomal dominant, *porphobilinogen (PBG) deaminase
deficiency* - abdominal pain, neuropsychiatric, reddish-brown urine that darkens. Worse
with alcohol/smoking. Treat with IV glucose or heme to downregulate aminolevulinate
(ALA) synthase --- PBG & ALA accumulate, causing symptoms
Two most common adverse effects of long-term *lithium* therapy (can also cause these
same effects in a fetus) - Hypothyroidism & nephrogenic diabetes insipidus (lithium =
bipolar mood stabilizer)
How to get shit out of the lungs: 3 levels, 3 processes - upper airway -
coughing/sneezing
bronchi->terminal bronchioles - mucociliary transport
respiratory bronchioles->alveoli - phagocytosis by alveolar macrophages
2 specific features of Graves disease (TRAb-mediated hyperthyroidism) -
Ophthalmopathy (proptosis) and pretibial myxedema
Gerstmann Syndrome - damage/stroke to angular gyrus of dominant (left-sided) parietal
association cortex (4 signs) - 1. Agraphia (inability to write)
2. Acalculia (inability to math)
3. Finger agnosia (inability to identify individual fingers on hand)
4. Left-right disorientation
---Nondominant (right-sided) lesions to parietal lobe result in hemi-neglect
First line treatment for Wilson Disease - Copper chelator (*penicillamine*) "copper
penny"
[low ceruloplasmin, Kayser-Fleischer rings, atrophy of basal ganglia]
, First line treatment for iron overdose - Iron chelator (Deferoxamine, Deferasirox,
Deferipone)
Lead poisoning - first line treatment? symptoms? --- blue "lead lines" at junction of teeth
& gums, basophilic stippling of RBCs on peripheral blood smear - children in old houses
eating paint chips or adults exposed to ammunition or batteries - Edetate calcium
disodium (CaNa2 *EDTA*) (increases urinary excretion) -- weakness (microcytic
hypochromic anemia), abdominal pain, constipation, neurotoxicity -- inhibition of
ferrochelatase and d-aminolevulinic acid (ALA) dehydratase in heme synthesis
pathway, instead incorporates zinc into protoporphyrin -- could also use dimercaprol,
succimer, penicillamine
Sarcoptes scabiei (mites & eggs) (Scabies) - presentation - Highly contagious, rapidly
spreading, intensely pruritic rash (usually worse at night) - wrist, fingers, finger webs,
palms
Angiogenesis driven by what 2 factors: - VEGF - vascular endothelial growth factor
FGF - fibroblast growth factor
Leydig vs Sertoli cells - LH -> Leydig -> Testosterone
FSH -> Sertoli -> (Inhibin B)
GnRH
t(15;17) and Auer Rods (stain for myeloperoxidase) - Acute Promyelocytic Leukemia
(APML) - fusion gene results in abnormal retinoic acid receptor, so treat with all-trans
retinoic acid - also associated with DIC
Potter Sequence - caused by renal anomaly (decreased urine output ->
oligohydramnios): newborn with pulmonary hypoplasia, along with facial & lower limb
deformities (compression) --- maternal use of ACEi/ARB can cause this, because
Angiotensin II is required for normal renal development
Carotid sinus massage, valsalva, and cold water immersion are _________ maneuvers.
Can be used to terminate paroxysmal supraventricular tachycardia. - Vagal maneuvers
- leads to increase in parasympathetic tone (bradycardia, hypotension, sometimes
syncope) --- Carotid sinus afferent limb is glossopharyngeal nerve (CN IX), efferent limb
is vagus (CN X).
What nerve is vulnerable to injury in fibular neck fractures? What's the deficit? -
Common peroneal (fibular) nerve -> causes weakness of foot dorsiflexion & eversion,
and loss of sensation over dorsum of foot.
Raphe nuclei in the CNS release what neurotransmitter? - Serotonin (target of SSRIs,
SNRIs, TCAs, etc.)
