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USMLE 26

  1. What causes Paroxysmal nocturnal hemoglobinuria?
    Caused by a mutation in the PIGA gene in population of hematopoietic stem cells that causes absence of the glycosylphosphatidylinositol anchor and associated deficiency of CD55 (Decay-accelerating factor) and CD59 (Mac inhibitory protein) complement inhibitor proteins.
  2. This type of anemia is caused by complement-mediated hemolysis.
    Paroxysmal nocturnal hemoglobinuria
  3. This type of anemia acquires its mutation in a hematopoietic stem cell.
    Paroxysmal nocturnal hemoglobinuria.
  4. Describe the clinical presentation of Paroxysmal nocturnal hemoglobinuria.
    • Coombs - hemolytic aneia
    • Leukopenia
    • Aplastic anemia
    • Pancytopenia
    • Ascities
    • Thrombocytopenia 
    • Venous thrombosis
    • Thrombotic complications (Budd chiari)- due to release of free hemoglobin and other prothrombotic factors.
  5. What is the marker and function of Mac inhibitory protein?
    CD59- inhibits complement hemolysis 
  6. What is CD59?
    • Mac inhibitory protein
    • Inhibits complement mediated hemolysis
  7. What is CD55?
    • Decay-accelertating factor
    • Inhibits complement-mediated hemolysis
  8. What is Factor V Leiden?
    • Production of a mutant factor V that is resistant to degradation by activated Protein C. 
    • MCC of inherited HYPERCOAGULABILITY in whites.
  9. What are the branches of the splenic artery and which is most vulnerable to ischemic injury in the event the splenic artery is blocked?
    • The splenic artery gives several branches off to the pancreas and stomach before reaching the spleen.
    • 1. Pancreatic artery
    • 2. Short gastric arteries- most vulnerable to ischemic injury
    • 3. Left gastroepiploic artery- less vulnerable due to strong anastomoses with right gastroepiploic artery
    • Image Upload 2
  10. What are the branches of the celiac trunk?
    • 1. Common hepatic
    • 2. Splenic artery
    • 3. Left gastric artery
  11. Where do the short gastic arteries branch from?
    • Splenic artery
    • They have poor anastomoses if splenic artery is blocked.
  12. Where does the right gastric artery arise from?
    • Proper hepatic artery
    • Image Upload 4
  13. Where does the gastroduodenal artery arise from?
    Common hepatic artery
  14. Where does the right gastroepiploic artery arise from?
    • Gastroduodenal artery
    • It forms an anastomoses with the left gastroepiploic artery.
  15. Where does the left gastroepiploic artery arise from?
    • Splenic artery
    • It forms an anastomoses with the right gastroepiploic artery.
  16. What is responsible for testes development (containing Serotoli and Leydig cells)?
    SRY gene on Y chromosome codes for testis determining factor which is responsible for gonadal differentiation into testes containing Serotoli and Leydig cells.
  17. What is the function of the SRY gene?
    The SRY gene on Y chromosome codes for testis determining factor which promotes development of the testes which houses Leydig and Sertoli cells.
  18. What is the function of Sertoli cells in gonadal development? What happens  to genital characteristics if sertoli cells are suppressed in males?
    • Sertoli cells secrete Mullerian inhibitory factor which suppress development of paramesonephric ducts. Without sertoli cells or MIF, the paramesonephric ducts go on to develop into the FEMALE INTERNAL GENITALIA (e.g. fallopian tubes, uterus)
    • Male has internal male and female genetalia, external male genetalia.
  19. What is the function of leydig cells in gonadal development? What happens to genital characteristics if Leydig cells are suppressed in males?
    • Leydig cells secrete testosterone which stimulate the mesonephric (Wolffian) ducts to develop into male internal genitalia (e.g epididymis, vas deferens). Testosterone is converted to dihydrotestosterone which induce development of male external genetalia.
    • Underdeveloped male internal and external genetalia.
  20. What is function of H1 histone?
    Helps to package the nucleosomes into more compact structures by binding and linking DNA between adjacent nucleosomes.
  21. What is the function of ubiquitin?
    Tags proteins for degradation by proteasome.
  22. What is prevalence?
    • Measure of the total cases at a particular point in time.
    • = # of existing cases/ # of people at risk
  23. Crescent formation on light microscopy is diagnostic for which glomerular disease?
    Rapidly progressive (crescentic) glomerulonephritis
  24. What do crescents consist of in RPGN?
    • Fibrin**
    • Glomerular parietal cells
    • Monocytes
    • Macrophages
    • Plasma proteins (e.g C3b)
  25. Which amino acid codes for phenylalanine?
    UUU & AUU
  26. What is the action of Menotropin?
    Menotropin (human menopausal gonadotropin) acts like FSH, leads to the formation of a dominant ovarian follicle.
  27. What is the use of β-hCG in fertility?
    Stimulates LH surge - causes rupture of dominant follicle, leading to ovulation.
Author
rere_girl4ever
ID
294403
Card Set
USMLE 26
Description
USMLE 26
Updated

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