Mod 4 Embryology

  1. What are the 5 important parts of the tube that will eventually form the heart?
    • 1) outflow tracts (aorta and pulm artery)
    • 2) bulbus cordis (rt ventricle)
    • 3) ventricle (Lt. ventricle)
    • 4) atrium (L and R atrium)
    • 5) sinus venosus (inflow to atria, left side mostly disappears (becomes coronary sinus), right side remains and becomes vena cavae)
  2. Describe the embryological basis for atrial septal defects
    • failure of septum secondum to completely cover ostium secondum
    • incomplete partitioning of the atria
  3. describe the embryological basis of atrioventricular septal defects
    • failure of endocardial cushions to fuse: septum primum cant develop, I/V septum cant close, improper formation of valves
    • results in a left to right shunt and congestive heart failure
  4. What are the possible embryological origins of ventricular septal defects?
    • Incomplete growth of I/V septum
    • small perforations in I/V septum
    • abnormal development of truncus arteriosus swellings
    • atrioventricular septal defects
  5. What is the embryological cause of persistent truncus arteriosus
    • failed septation of TA
    • right and left circulation enter a common outflow tract
    • cyanotic disease
  6. What is the embryological origin of transposition of the great vessels
    • no spiral growth in trunctus arteriosus
    • creates two closed loops
    • fatal: ductus arteriosus will keep infant alive for a little while
  7. What are the 4 concurrent malformations of the tetralogy of fallot?
    • pulmonary valve stenosis
    • overriding aorta
    • ventricular septal defect
    • right ventricle hypertrophy
  8. Name and describe the 3 fetal vascular shunts
    • ductus venosus: shunts most blood past liver and to IVC
    • foramen ovale: shunts most blood from RA to LA
    • ductus arteriosus: shunts blood from the pulmonary trunk to the aorta
  9. What circulatory changes happen at birth
    • vasodilation of lung vessels/constriction of ductus arteriosus (more flow to lungs)
    • constriction of umbilical arteries (decrease of flow from these arteries)
    • increase of flow to lungs closes foramen ovale
    • closure of ductus venosus increases systemic circ resistance
  10. What CV changes happen to a mother in pregnancy?
    • The rules of 40%:
    •   -40% increase in blood volume
    •   -40% increase in CO
    •   -a further 40% increase in CO in labour
    • Blood can more easily clot
    • Blood pressure WILL not increase (increase in CO is compensated by a decrease in systemic vascular resistance)
  11. Where does hematopoiesis happen in the fetus?
    • before 5 weeks: yolk sac
    • after week 5: mostly in liver
    • ultimately bone marrow will take over
Card Set
Mod 4 Embryology
Mod 4 embryology