Practice sessionHEALTHCARE & MEDICAL EXAMSMEDICAL LICENSING

USMLE (United States Medical Licensing Examination) Practice Exam 10

Practice exam for USMLE (United States Medical Licensing Examination).

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Question 1 of 500%

Time remaining180:00

Attempts allowedUnlimited

Difficulty mixE • M • H

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Question 1

MEDIUM

180:00

A 56-year-old man with long-standing hypertension is found to have concentric left ventricular hypertrophy on echocardiography. A myocardial biopsy shows enlarged cardiomyocytes with increased sarcomere content. Which intracellular signaling pathway most directly mediates this pressure-overload hypertrophic response?

Pressure overload (eg, hypertension, aortic stenosis) triggers pathologic cardiac hypertrophy via calcium-dependent signaling, notably calcineurin activation, which dephosphorylates NFAT allowing nuclear translocation and transcription of hypertrophic genes. Caspase-3 mediates apoptosis, not hypertrophy. cGMP signaling is more associated with vasodilation and can counter hypertrophy in some contexts.

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Activation of calcineurin leading to nuclear factor of activated T-cells (NFAT) transcription

Activation of caspase-3 leading to DNA fragmentation

Activation of guanylyl cyclase leading to increased cGMP

Activation of protein kinase A leading to increased L-type calcium channel opening

Inhibition of HMG-CoA reductase leading to decreased prenylation of small GTPases

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USMLE (United States Medical Licensing Examination) Practice Exam 10

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