UWorld_1.17 Flashcards Preview

USMLE Step 1 > UWorld_1.17 > Flashcards

Flashcards in UWorld_1.17 Deck (24)
Loading flashcards...
1

Presentation of Fragile X

  • more common/severe in males
  • mild-moderate cognitive impairment, speech/language delay, ADHD, mild autism 
  • macroorchidism
  • prominent jaw, long face, large ears, cleft palate
  • mitral valve prolapse
  • short height, joint laxity, scoliosis, pes cavus, double-jointed thumbs, single palmar crease

2

Cause of Fragile X

  • highest inherited cause of cognitive impairment
  • increase in trinucleotide repeat in FMR1 gene on X chromosome

3

Presentation of CNIII palsy

  • unilateral headache
  • eye pain
  • dilated, unreactive pupil
  • diplopia
  • ptosis
  • ipsilateral eye = "down and out"

4

Cause of CNIII palsy

  • CN III runs between posterior cerebral and superior cerebellar artery
  • aneurysm @ either vessel ==> CNIII palsy 

5

Calculation of number needed to harm

  • NNH = number of people that must be treated in order to harm 1 person
  • NNH = 1/attributable risk
  • attributable risk = adv.event ratetreatment - adv.event rateplacebo

6

Isoproteronol MOA

  • agonist at B1 and B2 receptors w/no alpha receptor activity ==>
    • increase in cardiac contractility (B1)
    • vascular smooth muscle relaxation (B2)

7

Major process used to maintain blood glucose levels @ 18-24 hrs

  • gluconeogenesis = glucose formed from lactate, glycerol, and amino acids

8

Important steps in gluconeogenesis

  1. pyruvate ==> oxaloacetate (pyruvate carboxylase) [@ mitochondria]
  2. OAA ==> malate (malate dehydrogenase) [@ mitochondria]
  3. malate ==> OAA ==> phosphoenolpyruvate (PEP carboxykinase = "PEPCK") [@ cytosol]
  4. PEP ==> glucose (fructose-1,6-bisphosphatase & glucose-6-phosphatase)

9

unsteady gait + blanching nests of distended capillaries + pulmonary infections ==> dx? + mechanism

  • Ataxia telangectasia
  • [autosomal recessive] mutation @ ATM ("Ataxia telangectasia mutated") gene = DNA break repair ==>
    • sensitive to xray radiation
    • cerebellar ataxia
    • telangectasias = blanching nests of distended cappilaries
    • predisposed to hematologic malignancies
  • IgA deficiency ==> predisposition to respiratory infections

10

Nerve coursing near piriform recess + fxn

  • internal laryngeal nerve (branch of CN X) courses superficially through mucosa @ piriform recess
    • fxn = afferent cough reflex
    • can be damage by food objects caught in piriform recess or in efforts to retrieve them

11

Factors ==> increased risk of renal calculi

  • increased concentrations of:
    • calcuim
    • uric acid
    • oxalate
    • phosphate
  • decreased water

12

Factors ==> decreased risk of renal caculi

  • increased water intake
  • increased citrate ==> binds free Ca and prevents precipitation and facilitates excretion

13

Rates of metabolism of various non-glucose sugars

  • Fructose = fastest
    • phosphorylated @ liver ==> fructose-1-P ==> bypasses PFK-1 = rate-limiting step
  • other sugars metabolized slower than fructose:
    • Galactose ==> glucose-6-P ==> glycolysis
    • Mannose ==> fructose-6-P ==> glycolysis

14

Cresent formation @ kidney on light microscopy ==> dx?

rapidly progressive glomerulonephritis

15

Mechanism of rapidly progressive glomerulonephritis

  • RPG ==> formation of crescent formation + focal necrosis
  • crescents = glomerular parietal cells, monocytes, macrophages, fibrin ==> sclerotic ==> irreversible renal injury

16

Muscle contraction @ skeletal msucle vs. cardiac muscle

  • skeletal muscle
    • AP ==> L-type-Ryr ==> Ca in T-tubule system (most of Ca from sarcoplasmic reticulum) ==> contraction
    • NO DEPENDENCE ON EXTRACELL Ca
  • cardiac muscle
    • AP ==> opening L-type Ca channels ==> entry of Ca ==> contraction
    • DEPENDENT ON EXTRACELL Ca

17

Vascular rxn to intimal/endothelial injury

  • hyperplasia and fibrosis
  • mostly mediated by medial smooth muscle cells
    • injured endothelial cells release platelet-derived growth factor ==> migration and proliferation of mSMCs
    • vascular cell-adhesion molecules (VCAMs) allow attachment of WBCs ==> release of cytokines ==> also attract mSMCs

18

Embryonic origin of melanocytes = ?

neural crest cells

19

intensly pruritic rash on flexor surfaces, worse at night, usually @ kids or those who work w/kids ==> dx? + mechanism

  • Scabies = infestation of sarcoptes scabiei mite
  • Type IV hypersensitivity rxn to mites and eggs
  • erythematous papules + excoriations; rapidly spreading

20

Characteristics of HepA infection

  • commonly asymptomatic or subclinical (anicteric) in children; self-lmiting 
  • can also: N/V, jaundice, RUQ pain, malaise/fatigue, aversion to smoking
  • usually uncommon but more severe @ adults

21

Extent/fxn of mucous and cilia @ lungs

  • cilia = trachea ==> respiratory bronchials
  • mucous (goblet cells) = interspersed from trachea ==> larger bronchials (not present @ terminal bronchials)
  • mucous + cilia ==> mucociliary clearance of foreign particles and organisms

22

Common organisms + treatment of urethritis in young male

  • organisms = N. gonorrheae or C. trachomatis
  • N. gonorrhea tx = ceftriaxone
  • C. trachomatis = doxycycline or azithromycin

23

Tx of acute mania

  • mood stabilizers = lithium, valproate, carbamazepime 
  • + atypical antipsychotic = olanzapine

24

Decks in USMLE Step 1 Class (97):