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0 - USMLE Step 1 > Uworld > Flashcards

Uworld Flashcards

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USMLE® Step 1 flashcards
1
Q

List 8 locations where you find type I collagen?

A
  • Dermis
  • Bone
  • Tendons
  • Ligaments
  • Dentin
  • Cornea
  • Blood vessels
  • Scar tissue
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2
Q

What type of collagen is affected in osteogenesis imperfecta?

A

Type I collagen

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3
Q

List 3 locations where you find type II collagen

A
  • Cartilage
  • Vitreous humor
  • Nucleus pulposus
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4
Q

List 7 locations where you find type III collagen?

A
  • Skin
  • Lungs
  • Intestines
  • Blood vessels
  • Bone marrow
  • Lymphatics
  • Granulation tissue
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5
Q

Type IV collagen is found where?

A

Basement membranes

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6
Q

Due to the overlap of normal behavior in preschoolers and sx’s of ADHD, the diagnosis is not given before what ages?

A

4-5 y/o

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7
Q

What is the embryological defect comprising Pierre-Robin sequence and what is seen in these children?

A
  • Severe micrognathia results in posterior displacement of the tongue (glossoptosis)
  • Prevents further fusion of the secondary palate (cleft palate)
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8
Q

Which blot procedure is used for DNA, mRNA, and protein?

A
  • DNA = Southern blot
  • mRNA = Northern blot
  • Protein = Western blot
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9
Q

The best method for determining whether a gene is being expressed is by using what type of blot?

A

Northern blot for mRNA; will show if gene of interest is being transcribed

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10
Q

Which interleukin is produced by macrophages infected by mycobacteria, which in turn stimulates T cells and NK cells to produce IFN-gamma?

A

IL-12

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11
Q

Autosomal recesssive deficiencies of what receptor result in disseminated mycobacterial disease in infancy or early childhood?

A

IFN-gamma receptor

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12
Q

Leukocyte adhesion deficiency is a rare immunodeficiency resulting from a defect in what?

A
  • CD18
  • Present w/ delayed separation of umbilical cord, recurrent cutaneous infections w/o pus formation, and poor wound healing
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13
Q

Injury to a branch of which nerve during appendectomy causes decreased sensation at the suprapubic region?

A

Anterior branch of Iliohypogastric n.

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14
Q

Which nerve arises from L2-L4 roots and innervates the skin of the medial thigh + provides motor function to the adductor ms. of the LE?

A

Obturator n.

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15
Q

Which nerve arising from L1 accompanies the spermatic cord through the superficial inguinal ring providing sensation to the upper and medial thigh and parts of the external genitalia?

A

Ilioinguinal n.

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16
Q

Left ventricular gallops (S3 and/or S4) are best heard how?

A

Using bell over the cardiac apex while pt is left lateral decubitus and listening at end of exhalation

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17
Q

Sudden upward jerking of the arm at the shoulder can cause injury to which nerves?

A

Lower trunk of brachial plexus (C8-T1) contributing to median and ulnar n.

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18
Q

Which fetal anomalies associated with decreased fetal swallowing can lead to polyhydramnios?

A
  • GI obstruction: esophageal, duodenal, or intestinal atresia
  • Anencephaly
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19
Q

Brown Sequard syndrome results from hemisection of the spinal cord and is characterized by what 3 findings?

A
  • Ipsilateral spastic paralysis (due to corticospinal tract injury)
  • Ipsilateral loss of tactile/vibratory/position sensation (dorsal columns)
  • Contralateral loss of pain and temp (spinothalamic tract) 1-2 levels below the lesion
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20
Q

In patients with PKU what AA becomes essential and why?

A

Tyrosine as it cannot be synthesized from phenylalanine in these pt’s

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21
Q

Which immune cells play a prominent role in defense against parasitic infection; predominantly via what substance?

A
  • Eosinophils
  • Release major basic protein from their granules, which acts as a potent toxin
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22
Q

Which fungi is associated with branching hyphae (25°C) and on biopsy is large, round yeasts w/ doubly refractile wall and single broad-based bud?

A

Blastomyces dermatidis

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23
Q

Which fungi is associated with oval yeast cells found within macrophages?

A

Histoplasma capsulatum

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24
Q

Biopsy of which fungal infection will show cells covered in budding blastoconidia?

A

Paracoccidioides brasiliensis

25
Q

Respiratory bronchioles lack which 2 features found in the bronchi?

A

Cartilage and glands

26
Q

Acute intermittent porphyria (AIP) may result from an autosomal dominant defect in which enzyme?

A

Porphobilinogen deaminase (PBGD)

27
Q

What is the 5 P’s mnemonic for the clinical manifestations of Acute Intermittent Porphyria?

A
  • Painful abdomen
  • Port wine - colored urine
  • Polyneuropathy
  • Psychological disturbance
  • Precipitated by drugs (and alcohol and starvation)
28
Q

A patients urine turning black when exposed to air is a characteristic finding of what disease?

A

Alkaptonuria (autosomal recessive); deficiency of homogentisic acid dioxygenase

29
Q

What is the function of T-tubules found in striated muscle?

A
  • During contraction, allow depolarization impulse to rapidly propogate thru interior of muscle fiber
  • Ensures Ca2+ release occur uniformly throughout the fiber, allowing for synchronized contraction of myofibrils in each cells
30
Q

Describe the route of an embolus leading to retinal artery occlusion.

A

Internal carotid –> Ophthalmic a. –> Retinal a.

31
Q

Intellectual disability, gait or posture abnormality, eczma, and a musty body odor are signs of what disease; inherited how?

A

PKU; autosomal recessive

32
Q

Which cell structure can be identified on electron microscopy by their characteristic double membrane and wavy cristae?

A

Mitochondria

33
Q

What is the most common non-nuclear DNA found in eukaryotic cells, which resembles prokaryotic DNA (small circular chromosome)?

A

Mitochondrial DNA (mtDNA)

34
Q

What is the karyotype of a complete vs. partial hydatidiform mole?

A
  • Complete: 46,XX
  • Partial: 69,XXY or 69,XXX
35
Q

What is the embryological defect leading to Tetralogy of Fallot?

A

Abnormal neural crest cell migration –> anterior and cephalad deviation of infundibular septum

36
Q

What is the most common trigger for atrial fibrillation?

A

Aberrant electrical foci in the pulmonary veins near their ostia into the left atrium

37
Q

An irregularly irregular rhythm with variable R-R intervals and absence of P wavs on ECG is consistent with what?

A

Atrial Fibrillation

38
Q

What is Hartnup disease; inheritance pattern; major clinical manifestations?

A
  • Autosomal recessive disorder due to inactivating mutations affecting neutral AA transporter; particularly affecting tryptophan
  • Clinical manifestations due to niacin deficiency: pellagra-like skin eruptions + cerebellar ataxia
  • Excessive amounts of neutral AA’s in the urine
39
Q

What is unique about DNA polymerase I?

A
  • Only prokaryotic polymerase that has 5’ to 3’ exonuclease activity; in addition to 3’ to 5’ polymerase/exonuclease activities
  • Functions to remove RNA primer and repair damaged DNA sequences
40
Q

Describe the murmur and location heard with patent ductus arteriosus (PDA)?

A

Continous murmur heard best in the left infraclavicular region with maximal intensity at S2

41
Q

Optic tract lesions result in what type of visual field defect?

A

Contralateral homonymous hemianopia and relative afferent pupillary defect (Marcus Gunn pupil)

42
Q

Budding yeasts with thick capsules are characteristic of which organism?

A

Cryptococcus neoformans

43
Q

Where is the majority of the water filtered by the glomeruli reabsorbed, regardless of hydration status?

A

Proximal tubules

44
Q

How do you calculate attack rate of a study?

A

of people affected / total # of people at risk

45
Q

Primary oocytes arrest in which phase of cell cycle until ovulation and then secondary oocytes arrest in which phase until fertilization?

A
  • Primary oocytes in prophase of meiosis I until ovulation
  • Secondary oocytes in metaphase of meiosis II until fertilization
46
Q

Which enzyme released by injured hepatocytes and bacteria hydrolyzes bilirubin glucuronides to unconjugated bilirubin leading to pigmented stones?

A

Beta-glucuronidase

47
Q

Why must patients receive Mefloquine chemoprophylaxis for 4 weeks upon return from trip to areas where P. falciparum is endemic?

A
  • To ensure that parasistes released from liver are destroyed when they infect RBC’s (liver schizonts rupture over 8-30 days)
  • Mefloquine actively destroyes replicating parasites within RBC’s, however, is inactivated in liver and has no efficacy against hepatic schizonts
48
Q

Gallstone ileus results from passage of a large gallstone through a cholecystenteric fistula into the small bowel where it ultimately causes obstruction where?

A

Ileum

49
Q

Primary biliary cholangitis presnts with similar histopathological findings in the liver as what other condition?

A

GVHD

50
Q

Isolated systolic HTN is due to what?

A

Age-related stiffness and decreased compliance of the aorta and major peripheral arteries

51
Q

What is the effect of an increase in estrogen activity as seen in pregnancy or post-menopausal estrogen replacement therapy?

A

↑ the level of TBG –> ↑ in total T4 levels as well as total T3

52
Q

What is the gold standard test for detecting a chromosomal microdeletion?

A

FISH

53
Q

Vascular beds in which organ are unique in that as tissue O2 content decreases the arterial/arteriolar resistance increases?

A

Lungs –> diverts blood away from underventilated lung regions toward well-ventilated lung areas to minimize V/Q mismatch = efficent gas exchange

54
Q

Serum levels of what are the most sensitive test for hypothyroidism?

A

TSH

55
Q

A 2-year old girl with ambiguous genitalia, HTN, and hypokalemia is most likely to have a deficiency in what?

A

11ß-hydroxylase = Congenital adrenal hyperplasia

56
Q

What is the most common GI abnormality associated with Down Syndrome?

A

Duodenal Atresia: first few days of life, bilious emesis; “double-bubble” sign

57
Q

What is the hallmark of peroxisomal disorders (i.e., Zellweger syndrome, Adrenoleukodystrophy)?

A

Buildup of VLCFA’s and branched-chain (i.e., phytanic) FA’s due to impaired oxidation

58
Q

What is the most common cause of alarming bloody or serosanguineous (i.e., blood tinged) nipple discharge; what is seen histologically?

A
  • Intraductal papilloma
  • Proliferation of papillary cells in a duct or cyst wall with fibrovascular core

0 - USMLE Step 1 (22 decks)

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