USMLE 29

  1. Describe X-linked dominant inheritance.
    • Affected father will transmitt all to daughters but no sons.
    • Mothers transmit 50% to daughters and sons
  2. In this mode of inheritance, both parents must at least be carriers (heteroyzgous) for the trait in order to produce the affected offspring.
  3. What is the condition below?
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    Dextrocardia
  4. What is the cause of change depicted by the dashed line?
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    • Anaphylaxis 
    • Causes widespread venous and arteriolar dilation along with increased capillary permeability ⇩venous return

    • Cardiac contractility also increase as the body attempts to maintain blood pressure.
  5. What is the cause of change depicted by the dashed line?
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    • Myocardial infarction
    • Decrease in cardiac output due to loss of contractility
  6. What is the cause of change depicted by the dashed line?
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    • Excessive hydration 
    • ⇧in blood volume
  7. What is the cause of change depicted by the dashed line?
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    Hemorrage
  8. What is the cause of change depicted by the dashed line?
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    • Chronic anemia- increases cardiac output to meet metabolic demands of the tissues.
    • ⇧ venous return occurs due to ⇩blood viscosity.
  9. What corresponds to the opening snap in mitral stenosis?
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    C- opening snap- mitral stenosis
  10. What is the pathology below?
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    Pituitary macroadenoma
  11. How does hemolytic disease of the newborn occur?
    Rh- mothers exposed to fetal Rh+ blood (often during delivery) may make anti-Rh(D) IgG antibodies which can cross the placenta and cause fetal hemolysis in the next fetus that is Rh+
  12. What is the pathology below and what causes it?
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    • Caput medusae 
    • Distended paraumbilical veins 
    • Paraumbilical ↔ small epigastric veins of the anterior abdominal wall
  13. The following measurements were taken from a healthy 33-year old volunteer.
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    Which of the following is the best estimate of the filtration fraction in this patient  assuming a urine flow of 1.0 ml/min?
    • FF= GFR/ RPF
    • FF= [(Crurine X Crserum)/ Urine flow] / [(PAHurine X PAHserum) / Urine flow]
    • FF= [(200 X 0.1) / 2] / [(100 X 1.0) / 0.2] = 100/500 = 0.2 = 20%
  14. What is a typical filtration rate for a normal individual?
    20% or 0.20
  15. What causes calcium efflux prior to myocyte relaxation?
    Ca2+-ATPase and Na+/Ca2+ exchange mechanisms
  16. Label the diagram
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    • 1 = prostate
    • 2 = rectum3 = obturator internus4 = ischium5 = body of pubis6.= pubic symphysis7 = femoral artery8 = femoral vein
  17. Which drugs have negative chronotropic effects → ⇩heart rate?
    • β-blockers (metotrolol, atenolol)
    • Ca2+ channel blockers- verapamil, diltiazem
    • Digoxin
    • Amiodarone and Soltalol (class III antiarrythmics)
    • Cholinergic agonists (Pilocarpine, rivastigmine)
  18. A young couple who recently immigrated from Eastern Europe brings their 3-year old son to your office for evaluation of an eczematous rash. On exam, you observe that the child shows signs of mental retardation and has a mousey odor. What is the likelihood that his couple's next child will be affected with the same disease?
    • Phenylketonuria - autosomal recessive
    • p1= probability that the mother transmits the mutant allele = 1/2
    • p2= probability that the father transmits the mutant allele = 1/2
    • The probability that a child will inherit a mutant allele from each carrier= p1 X p2 = 1/4
  19. Which enzymes are required by branched-chain α-ketoacid dehydrogenase?
    • 1. Thiamine pyrophosphate
    • 2. Lipoate
    • 3. Coenzyme A
    • 4. FAD
    • 5. NAD
  20. How do we treat maple syrup urine disease?
    • Restriction of isoleucine, leucine, valine in diet
    • THIAMINE SUPPLEMENTATION
  21. In which disease is Galactocerebrosidase deficient?
    Krabbe disease
  22. What is pleiotropy? Give an example.
    • One gene contributes to multiple phenotypic effects.
    • E.g Phenylketonuria
  23. Patient receives a transplant. About a week after his surgery the patient develops skin rash and bloody diarrhea. What is the cause of this condition? Explain the pathology.
    • Graft vs host disease
    • Graft T-cell sensitization against host MHC antigens
  24. What is the pathology below?
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    Meningioma
  25. This tumor of the brain arises from arachnoid villi.
    Meningioma
  26. Where do meningiomas arise from?
    Arachnoid villi
  27. This brain tumor is characteristic of concentric laminated calcifications.
    • Meningioma
    • Psammoma bodies
  28. Psammoma bodies are characteristic of this brain tumor.
    • Meningioma
    • Laminated calcifications
  29. Where are meningiomas most commonly located?
    • Most occurs in the CONVEXIVITIES OF HEMISPHERES and PARASAGGITAL REGION
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  30. This brain tumor often occurs in the convexity of the hemispheres.
    Meningioma
  31. This brain tumor often occurs in the parasaggital region of the brain
    Meningioma
  32. What symptoms can arise from a meningioma?
    • SEIZURES or focal neurologic signs
    • Compression of parasaggital cortex causes contralateral SPASTIC PARALYSIS OF THE LEG
  33. Describe this pathology. What causes it?
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    • Ptosis & "Down and out" gaze
    • Caused by a lesion to CN3 
    • Compression- berry aneurysm, uncal herniation
    • Ischemia- Diabetes mellitus
  34. What caution should be placed with taking other diuretics with ACE inhibitors. Why?
    • First dose hypertension is an adverse effect when initiating ACE inhibitors.
    • Risk factors: hyponatremia and hypovolemia 2o to diuretic therapy- Thiazides, Loop diuretics
  35. Which HIV gene produces capsid protein p24?
    gag
  36. What does the HIV gag gene encode?
    Nucleocapsid proteins p24 and p7
  37. This HIV gene encodes p7.
    gag
  38. What does the HIV pol gene encode?
    • Reverse transcriptase
    • Integrase 
    • Protease
  39. What does the HIV env gene encode?
    gp160, a precursor glycoprotein that is cleaved into viron envelope glycoproteins gp120 and gp41
  40. This HIV gene encodes gp120.
    env
  41. This HIV gene encodes gp41
    env
  42. This HIV gene enhances viral replication through downregulation of CD4 and MHC class I expression
    nef
  43. What is the funciton of the nef gene?
    Enhance viral replication through downregulation of CD4 and MHC class I expression
  44. Which HIV genes are required for viral replication?
    tat and rev
  45. What does the HIV tat gene encode?
    • Encodes a protein that transcriptionally activates other viral genes.
    • Expression of this gene is throught to contribute to the virulence of HIV
  46. Where is the lunate bone located?
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  47. Where is the trapezium bone located?
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  48. Where is the trapeziod bone located?
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  49. Describe the findings of organophosphate poisoning.
    • Diarrhea
    • Urination
    • Miosis
    • Bronchospasm
    • Bradycadia
    • Excitation of skeletal muscles and CNS
    • Lacrimation 
    • Sweating
    • Salivation
  50. How do we treat organophosphate poisoning?
    Atropine + Pralidoxine (regenerates AChE)
  51. What is the MOA of Trifoban?
    • Prevents platelet-platelet aggregation
    • Inhibits expression of GpIIb/IIIa
  52. What is the MOA of Eptifibatide?
    • Inhibits expression of GpIIb/IIIa
    • Prevents platelet to platelet aggregation
  53. Describe the pathogenesis of Syringomyelia.
    • Cystic dilation in the cervical spinal cord (a syrinx) slowly enlarges.
    • Causing damage to the VENTRAL WHITE COMISSUE (which the SPINOTHALAMIC TRACT runs through) and the ANTERIOR HORNS (which is the sire of lower motor neuron cell bodies)
    • Loss of temperature and pain sensation (e.g ppt keeps burning arms) and lower extremity weakness
  54. Describe the presentation of syringomyelia
    • Loss of upper extremity pain and temperature- e.g. person keeps burning/ bruising their hands
    • Hyporreflexia, lower extremity weakness
  55. How do we calculate cardiac output?
    • CO = Stroke volume X Heart rate
    •      = rate of O2 consumption/ (arterial O2 content- venous O2 content)
Author
rere_girl4ever
ID
298011
Card Set
USMLE 29
Description
USMLE 29
Updated