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USMLE > Qbank 3 > Flashcards

Qbank 3 Flashcards

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USMLE® Step 1 flashcards
1
Q

Which proteins recognize the stop codon in translation?

A

-releasing factors

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2
Q

Interferons a and b. Function? What cells produce them?

A

-produced by virus-infected cells (wide variety of eukaryotic cells) and prime neighboring cells that are uninfected (stimulates them to produce anti viral proteins) by helping to degrade viral nucleic acid and protein.

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3
Q

Why is pO2 in left atrium and ventricle lower than in pulmonary capillaries?

A
  • because oxygenated blood is mixed with deoxygenated blood from bronchial arteries that supply the lungs and thespian veins (from heart) that empties into the pulmonary vein
  • pO2 is ~104 in capillaries and drops to 100 by the left atrium
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4
Q

Where does methicillin resistant S. aureus commonly colonize in humans asymptomatically?

A

nasopharynx, esp Anterior nares

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5
Q

Doses of drugs such as digoxin should be reduced in elderly patients because of age-related reductions in?

A
  • renal clearance

- there is no rise in Cr because there is also a reduction in muscle mass with age

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6
Q

Pre-eclampsia triad.

A

-hypertension, proteinuria, edema

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7
Q

Embryonic layers that pituitary is derived from?

A
  • anterior pituitary: surface ectoderm

- posterior pituitary: neural tube/neuroectoderm

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8
Q

Which opioids can be used for diarrhea?

A

-loperamide and diphenoxylate

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9
Q

Mechanism of N-acetyl cysteine in CF patients?

A

-mucolytic agent, cleaves disulfide bonds in mucus glycoproteins to loosen thick sputum

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10
Q

maculopapular rash that starts at face and spreads to trunks and extremities: how to tell between rubella vs rubeola?

A

-finding of post auricular lymphadenopathy indicates rubella

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11
Q

Superficial dermal edema and lymphatic channel dilation. What skin condition?

A

-urticaria, aka hives.

form after mast cell degranulation.

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12
Q

IgG4 antibodies to Phopholipase A2 receptor causing proteinuria.

A

Idiopathic membranous nephropathy

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13
Q

Deficiency in lipoprotein lipase. Disease? Common presentation?

A
  • Type I hyper chylomicronemia. High chylomicrons, TG, cholesterol. Creamy supernatant.
  • commonly presents with recurring acute pancreatitis
  • eruptive/pruritic xanthomas.
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14
Q

In a deceleration injury to the aorta, where is the injury commonly located?

A

aortic isthmus, where ligament arteriosum attaches

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15
Q

Role of vitamin C in collagen synthesis?

A

-Cofactor of enzyme that carries out post translational hydroxylation of proline and lysine residues. Takes place at RER.

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16
Q

Mechanism of niacin for lipid lowering effect?

A
  • inhibits lipolysis in adipose tissue

- reduces hepatic VLDL synthesis

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17
Q

Strep pneumo and viridians. Which group is bile soluble?

A

Strep pneumo.

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18
Q

Eosinophilic apoptotic hepatocytes in acute hepatitis infection. What are the eosinophilic globules called?

A

Councilman bodies

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19
Q

What gene mutation commonly seen in melanoma?

A
  • BRAF (ser/thr kinase is gene product)

- oncogene that is activated

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20
Q

Where do majority of anal fissures occur?

A

posterior midline distal to dentate line

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21
Q

How is copper excreted in normal healthy person?

A
  • secreted into bile and excreted in bile

- some cleared by kidneys

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22
Q

Treatment for enterobiasis (pinworm)?

A

albendazole

-pyrantel palmoate for pregnant patients

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23
Q

Which amino acid is an immediate source of nitrogen in the urea cycle?

A

Urea’s nitrogen is derived from NH3 and Aspartate

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24
Q

Parasympathetic innervation to parotid gland for secretion by which nerve?

A

CN 9

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25
Q

The presence of what factor corresponds to virulence in mycobacterium?

A

Cord factor (a mycoside). Grow in serpentine cord on media. Inhibits neutrophils, causes mitochondrial destruction, induces release of TNF.

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26
Q

Pituitary apoplexy. Describe.

A
  • pituitary hemorrhage most often in preexisting adenoma.

- cardiovascular collapse can occur due to adrenocortical insufficiency

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27
Q

Carcinoid tumors are derived from?

A

Enterochromaffin cells (endocrine) of intestinal mucosa

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28
Q

Celecoxib is a selective _____ inhibitor?

A

selective COX 2 inhibitor

-COX 2 expressed on vascular endothelium and smooth muscle cells.

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29
Q

myotonia, muscle wasting, cataracts, testicular atrophy, frontal balding, arrhythmia. Difficulty with loosing grip after handshake. Disease? Mechanism of disease?

A

Myotonic Dystrophy or type 1.

-CTG trinucleotide repeat. AD.

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30
Q

Formation of cold agglutinins seen in?

A

Mycoplasma pneumonia infection
EBV
CLL

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31
Q

schizoaffective disorder vs. bipolar/depression with psychotic features

A

Schizoaffective
-psychotic symptoms must occur in absence of mood disorder for at least 2 weeks. Mood disorder is present majority of time with psychotic symptoms
BIpolar/depression with psychotic features
-Psychotic features occur exclusively during mood disorder

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32
Q

Best drug for lowering triglycerides?

A

Fibrates: upregulate LPL for increased TG clearance

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33
Q

Describe structure of tRNA

A
  • 75-90 nucleotides, cloverleaf form.
  • acceptor site is the CCA tail at 3’ end
  • T arm: thymine, pseudouracil, cytosine for tRNA ribosome binding
  • D arm: dihydrouracil residues for tRNA recognition by correct ammoniacal tRNA synthethase
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34
Q

Which DNA polymerase has 5’ to 3’ exonuclease activity to remove RNA primers?

A

DNA polymerase I

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35
Q

Transient vs permanent central DI, where is the damage?

A

transient: isolate posterior pituitary damage. surviving neurons can undergo axonal regeneration and release ADH into circulation
permanent: hypothalamus damage.

36
Q

Mechanism of infertility of kartegener’s syndrome vs CF

A
  • CF: bilateral absence of vas deferens. Azoospermia.

- Kartegeners: immotile spermatozoa.

37
Q

serious complication of methimazole and propylthiouracil?

A

agranulocytosis.

-suspect with onset of fever and sore throat.

38
Q

Serum marker for ovarian epithelial tumor.

A

CA-125.

39
Q

Migratory thembrophlebitis, jaundice with palpable nontender gallbladder. Suspect what cause? Risk factors?

A

Pancreatic cancer

  • Trousseau syndrome and courvoisier sign
  • risks: tobacco use, chronic pancreatitis, diabetes, age greater than 50, genetic predisposition
40
Q

What parts of the brain is atrophy most pronounced in Alzheimer’s disease?

A
  • Hippocampus

- also temporoparietal lobes

41
Q

greatest risk factor predisposing to aortic dissection?

A

-Hypertension, causing hyaline arteriolosclerosis of vasa vasorum, leads to atrophy of media. Aortic enlargement and increased wall stiffness. exacerbate aortic wall stress and increases risk of intimal wall tear.

42
Q

List the naked viruses

A

DNA: PAPP- polyomavirus, papillomavirus, adenovirus, parvovirus
RNA: calicivirus, picornavirus, reovirus, hepevirus

43
Q

Cause of narcolepsy.

A

Decreased hypocretin (orexin) production in lateral hypothalamus

44
Q

Infusion of what substance will make thiamine encephalopathy worse?

A
  • glucose
  • thiamine is a cofactor for PDH, a-ketoglutarate dehydrogenase, trnasketolase, and branched chain ketoacid dehydrogenase
  • giving glucose without thiamine will make ATP depletion worse
45
Q

Meningococcal meningitis prophalyxis for close contacts of infected patient?

A

Rifampin. Penetrates well into respiratory tract and will eliminate nasopharyngeal colonization.

46
Q

Which drug is an emergency antihypertensive that activates D1 receptors and also increases renal blood flow and causes natriuresis?

A

Fenoldopam.

-increases cAMP resulting in vasodilation

47
Q

HCO3-, PAH, Inulin, creatinine, Na, Cl-, urea, glucose, amino acids. Which sometimes increase/decrease as fluid runs along the PCT?

A

INCREASE: PAH, inulin, Cr, urea, Cl-
Decrease: glucose, amino acids, HCO3-

48
Q

How does digoxin lower heart rate and decrease AV nodal conduction?

A

-stimulates vagus nerve to increase parasympathetics to the heart.

49
Q

Recurrent sinopulmonary and GI tract infections. Blood transfusion causes anaphylactic disease. What is the deficiency?

A

IgA deficiency. They form Ig-G antibodies against IgA when transfused with blood that contain a little IgA.

50
Q

What does Hep D need to infect cells?

A

-needs to be coated with HbsAg

51
Q

which immunodeficiencies are predisposed to Giardia infections?

A
  • IgA def., Brutons X linked agammaglobinemia, CVID

- Secretory IgA is a major component of adaptive immunity against Giardia

52
Q

function of organ of Corti?

A
  • transduction of mechanical auditory forces to nerve impulses
  • prolonged exposure to loud noises can cause hearing loss due to damage to stereo ciliated hair cells of organ of Corti
53
Q

What anticoagulant drugs affect thrombin time?

A

Unfractionated heparin and direct thrombin inhibitors

54
Q

Describe 3 phases of acute tubular necrosis and the most significant complication during the last phase?

A
  1. Initiation: ischemic injury to renal tubule precipitate by MI, sepsis, hemorrhage, etc.
  2. Maintenance phase: oliguria, volume overload, increasing Cr/BUN. Hyperkalemia
  3. Recovery:Gradual increase in output resulting in high volume diuresis. Dehydration and Electrolyte abnormalities can ensue
    - Hypokalemia: most serious complication
55
Q

What is the major distinguishing factor between depression and atypical depression? What is good Rx for atypical depression?

A
  • Mood reactivity: improvement in mood in reaction to something positive
  • other features of atypical depression: increased appetite and sleep, rejection sensitivity, leaden fatigue
  • 1st line: CBT and SSRIs
  • 2nd line: Mao Inhibitors are good for atypical depression
56
Q

What features of drugs give preference to hepatic clearance instead of renal clearance?

A
  • lipophilicity and high Vd
  • high lipid solubility allows better entry into hepatocytes, and is easily reabsorbed in renal tubules so not cleared by kidneys
57
Q

What is the single most preventable cause of disease and death in the US?

A

smoking

58
Q

Histology of medullary thyroid cancer

A

uniform spindle shaped or polygonal cells with extracellular amyloid deposits.

59
Q

Where does neonatal intraventricular hemorrhage usually originate from?

A
  • germinal matrix: highly vascularized and cellular layer of sub ventricular zone where neurons and glial cells migrate from during development.
  • intraventricular hemorrhage (bleeding into lateral ventricles, e.g.) is a common complication of prematurity
60
Q

virulence factor that is bound to peptidoglycan cell wall of S. Aureus? what is its function?

A

Protein A
-it binds to Fc portion of IgG at the complement binding site and prevents complement activation. Impaired opsonization and phagocytosis

61
Q

What is nursemaid’s elbow?

A
  • radial head subluxation causing annular ligament to be torn/displaced
  • young children less than 5
  • arm is extended at elbow and forearm pronated
62
Q

What kind of channel is CFTR?

A

ATP gated chloride channel

63
Q

What is the length constant of axon? Also called space constant.

A

How far an electrical impulse can propagate along an axon

-myelin increases length constant and decreases time constant

64
Q

Characteristic histological findings in GERD?

A
  • inflammatory cells, including eosinophils
  • elongated lamina propia papillae
  • basal zone hyperplasia
65
Q

Which are the live attenuated vaccines?

A

-MMR, Sabin polio, nasal influenza, varicella, yellow fever

66
Q

Most common cause of coronary sinus dilation?

A

-elevated right heart pressure secondary to pulmonary hypertension

67
Q

Histology of intestines in abetalipoproteinemia

A
  • fat accumulation towards tip of villi
  • lipids absorbed cannot be transported into the blood
  • due to mutation of MTP gene, which functions in folding of ApoB and transfer of lipids to chylomicrons and VLDL for transport of TGs
  • absence of ApoB, chylomicrons, VLDL in blood
68
Q

Role of IgE and eosinophils in immune response against parasite

A
  • IgE and IgG coats parasites
  • binds Fc receptor on eosinophils, activates eosinophilic degranulation
  • antibody mediated cell mediated cytotoxicity.
69
Q

Causes of wound contracture?

A
  • MMP activity encourages myofibroblast proliferation at wound edges and scar tissue remodeling
  • pronounced MMP activity causes contractures
70
Q

At FRC, what is the airway pressure and the intrapleural pressure?

A
  • airway pressure is zero and there is no tendency to air to flow one way or the other
  • intrapleural pressure is -5
71
Q

The superior thyroid artery courses with what nerve?

A

Superior laryngeal nerve

72
Q

Mechanism of flutamide

A

competitive antagonist to the androgen receptor. If used as mono therapy, will cause increase in testosterone level due to negative feedback. Often used with leuprolide.

73
Q

During what lung volume is pulmonary vascular resistance the lowest?

A

Near FRC

74
Q

What findings using diagnostic imaging are specific to acute cholecystitis?

A

-Ultrasound: gallbladder wall thickening, pericholecystic fluid
-If ultrasound is not conclusive–>
cholescintigraphy can be used. Radio tracer is injected via IV and images taken. In acute cholecystitis, will show no uptake by gallbladder

75
Q

How does radiation initiate cell death?

A
  • causes double stranded DNA breaks

- creates ROS

76
Q

What type of vaccine is used for rabies?

A
  • Inactivated vaccine

- in post exposure prophylaxis: use vaccine and rabies immune globulin

77
Q

What deficiencies can lead to homocystinuria?

A
  1. Cystahionine syntheses deficiency: catalyzes first step of following, requires B6:
    - Homocysteine +serine—>cystathionine –>cysteine
  2. Decreased affinity of cystathionin synthase for pyridoxal phosphate
  3. homocysteine methyltransferase deficiency
    - homosysteine–>methionine (requires b12)
78
Q

Warfarin skin necrosis, what deficiency would you suspect in the patient?

A

Protein C deficiency. Already low protein C, adding warfarin causes quick drop in levels, leading to a procoagulant state since protein C and factor 7 are the first factors to be depleted.

79
Q

What is the prognosis for majority of patients infected with Hep C?

A
  • they progress to chronic stable Hep C
  • less than half develop cirrhosis
  • only 0-3 % develop HCC
  • 15-45% clear the infection
80
Q

Why do patients with nephrotic syndrome have an increased risk for thrombosis?

A
  • loss of ATIII in urine
  • creates a hyper coagulable state
  • Renal vein thrombosis is a common complication, leading to left sided varicocele in men
81
Q

Mechanism behind biliary colic as a complication of opioid drugs?

A

-causes contraction of sphincter of oddi, leading to increased pressures in bile duct and gallbladder

82
Q

Signs of irreversible cell injury.

A
  1. nuclear pyknosis, karyorrhexis, karyolysis
  2. plasma membrane damage
  3. lysosomal rupture
  4. mitochondrial permiability/vacuolization
83
Q

Shape of cryptococcus neoformas?

A

budding yeast or round/oval encapsulated cells.

84
Q

mechanism of influenza vaccine (injected)

A
  • vaccine induces neutralizing antibodies against hemagglutinin
  • when exposed to infection, will prevent viral entry into cells
85
Q

Coenzymes required for pyruvate dehydrogenase?

A
  • NAD, FAD, CoA
  • Thiamine
  • Lipoic acid
86
Q

Describe differentiation of T cells.

A
  • T cell precursor produced in bone marrow
  • migrate to Thymus and become CD4+CD8+ cell in cortex
  • Positive selection: TCR is able to recognize self MHC via interaction with thymic cortical epithelial cells
  • Become single positive CD4 or Cd 8 cells
  • Negative selection: via interaction with thyme medullary epithelial cells and dendritic cells. T cells with too strong affinity for self antigen or self MHC are eliminated

USMLE (4 decks)

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