FIRST AID FOR THE USMLE EXAM SCRIPT
FULL QUESTIONS AND CORRECT ANSWERS
GUARANTEED TO PASS
●● Bulbus cordis gives rise to __________.
Answer: Smooth parts (outflow tract) of left and right ventricles
●● Endocardial cushion gives rise to?
Answer: Atrial septum ,membraneous interventricular septum; AV &
semilunar valves
●● Primitive atrium gives rise to __________.
Answer: Trabeculated (muscular) portions of the left and right atria
●● Primitive ventricle gives rise to __________.
Answer: Trabeculated (muscular) portions of the left and right ventricles
●● Primitive pulmonary vein gives rise to __________.
Answer: Smooth part of the right atrium
●● Left horn of sinus venosus gives rise to __________.
Answer: Coronary sinus
,●● Right horn of sinus venosus gives rise to __________.
Answer: Smooth part of the right atrium (sinus venarum)
●● Right common cardinal vein and right anterior cardinal vein gives
rise to __________.
Answer: Superior vena cava (SVC)
●● When does the heart beat begin to beat spontaneously?
Answer: -4 weeks of development
-First functional organ in vertebrate embryos
●● What is cardiac looping?
Answer: -Primary heart tube loops to establish left-right polarity; begins
in week 4 of gestation.
●● Defect in left-right dynein (involved in L/R asymmetry) can lead
to___________, as seen in Kartagener syndrome (primary ciliary
dyskinesia).
Answer: Dextrocardia
●● What is a foramen/ostium?
Answer: opening
,●● What is a septum?
Answer: wall
●● Septation of atria (7 Steps)
Answer: 1. Septum primum grows toward endocardial cushions,
narrowing foramen primum.
2. Foramen secundum forms in septum primum (foramen primum
disappears).
3. Septum secundum develops as foramen secundum maintains right-to-
left shunt.
4. Septum secundum expands and covers most of the foramen
secundum. The residual foramen is the foramen ovale.
5. Remaining portion of septum primum forms valve of foramen ovale.
6. (Not shown) Septum secundum and septum primum fuse to form the
atrial septum.
7. (Not shown) Foramen ovale usually closes
soon after birth because of increased LA pressure.
●● Patent foramen ovale is caused by a failure of __________ and
___________ to fuse after birth. What can this lead to?
Answer: -Caused by failure of septum primum and septum secundum to
fuse after birth; most are left untreated.
, -Can lead to paradoxical emboli (venous thromboemboli that enter
systemic arterial circulation), similar to those resulting from an ASD.
●● Septation of the ventricles (3 steps)
Answer: 1. Muscular ventricular septum forms. Opening is called
interventricular foramen.
2. Aorticopulmonary septum rotates and fuses with muscular ventricular
septum to form membranous interventricular septum, closing
interventricular foramen.
3. Growth of endocardial cushions separates atria from ventricles and
contributes to both atrial septation and membranous portion of the
interventricular septum.
●● What is the most common congenital cardinal anomaly?
Answer: VSD
●● Most common location of VSD?
Answer: The membranous septum
●● Outflow tract formation
Answer: Truncus arteriosus rotates; neural crest and endocardial cell
migrations cause truncal and bulbar ridges that spiral and fuse to form
aorticopulmonary septum to form ascending aorta and pulmonary trunk.
FULL QUESTIONS AND CORRECT ANSWERS
GUARANTEED TO PASS
●● Bulbus cordis gives rise to __________.
Answer: Smooth parts (outflow tract) of left and right ventricles
●● Endocardial cushion gives rise to?
Answer: Atrial septum ,membraneous interventricular septum; AV &
semilunar valves
●● Primitive atrium gives rise to __________.
Answer: Trabeculated (muscular) portions of the left and right atria
●● Primitive ventricle gives rise to __________.
Answer: Trabeculated (muscular) portions of the left and right ventricles
●● Primitive pulmonary vein gives rise to __________.
Answer: Smooth part of the right atrium
●● Left horn of sinus venosus gives rise to __________.
Answer: Coronary sinus
,●● Right horn of sinus venosus gives rise to __________.
Answer: Smooth part of the right atrium (sinus venarum)
●● Right common cardinal vein and right anterior cardinal vein gives
rise to __________.
Answer: Superior vena cava (SVC)
●● When does the heart beat begin to beat spontaneously?
Answer: -4 weeks of development
-First functional organ in vertebrate embryos
●● What is cardiac looping?
Answer: -Primary heart tube loops to establish left-right polarity; begins
in week 4 of gestation.
●● Defect in left-right dynein (involved in L/R asymmetry) can lead
to___________, as seen in Kartagener syndrome (primary ciliary
dyskinesia).
Answer: Dextrocardia
●● What is a foramen/ostium?
Answer: opening
,●● What is a septum?
Answer: wall
●● Septation of atria (7 Steps)
Answer: 1. Septum primum grows toward endocardial cushions,
narrowing foramen primum.
2. Foramen secundum forms in septum primum (foramen primum
disappears).
3. Septum secundum develops as foramen secundum maintains right-to-
left shunt.
4. Septum secundum expands and covers most of the foramen
secundum. The residual foramen is the foramen ovale.
5. Remaining portion of septum primum forms valve of foramen ovale.
6. (Not shown) Septum secundum and septum primum fuse to form the
atrial septum.
7. (Not shown) Foramen ovale usually closes
soon after birth because of increased LA pressure.
●● Patent foramen ovale is caused by a failure of __________ and
___________ to fuse after birth. What can this lead to?
Answer: -Caused by failure of septum primum and septum secundum to
fuse after birth; most are left untreated.
, -Can lead to paradoxical emboli (venous thromboemboli that enter
systemic arterial circulation), similar to those resulting from an ASD.
●● Septation of the ventricles (3 steps)
Answer: 1. Muscular ventricular septum forms. Opening is called
interventricular foramen.
2. Aorticopulmonary septum rotates and fuses with muscular ventricular
septum to form membranous interventricular septum, closing
interventricular foramen.
3. Growth of endocardial cushions separates atria from ventricles and
contributes to both atrial septation and membranous portion of the
interventricular septum.
●● What is the most common congenital cardinal anomaly?
Answer: VSD
●● Most common location of VSD?
Answer: The membranous septum
●● Outflow tract formation
Answer: Truncus arteriosus rotates; neural crest and endocardial cell
migrations cause truncal and bulbar ridges that spiral and fuse to form
aorticopulmonary septum to form ascending aorta and pulmonary trunk.
