Embryology

Question 1

What does the truncus arteriosus give rise to?

Answer 1

The ascending aorta and pulmonary trunk

Question 2

Which embryonic structure gives rise to the smooth parts of the left and right ventricles?

Answer 2

Bulbus cordis

Question 3

What does the endocardial cushion give rise to?

Answer 3

Atrial septum
Membranous interventricular septum
AV and semilunar valves

Question 4

What does the left horn of the sinus venosus develop into?

Answer 4

Coronary sinus

Question 5

Which embryonic structure gives rise to the superior vena cava?

Answer 5

Right common cardinal vein and right anterior cardinal vein

Question 6

Which aortic arch develops into the common carotid arteries?

Answer 6

3rd arch

Question 7

Which aortic arch develops into the left and right pulmonary arteries?

Answer 7

6th arch

Question 8

Describe foetal circulation.

Answer 8

1. Oxygenated blood from the placenta enters the foetus through the umbilical vein
2. Within the foetus, the oxygenated blood bypasses the liver and combines with deoxygenated blood in the inferior vena cava
3. Blood empties into right atrium. As pressure is larger in the right atrium than the left, blood is shunted through the foramen ovale
4. Blood then moves into the aorta via the ductos arteriosus
5. Deoxygenated blood returns to the placenta via the umbilical arteries

Question 9

Describe postnatal circulation.

Answer 9

1. With the first breath, increased alveolar oxygen pressure causes vasodilation of pulmonary vessels
2. Umbilical vein constricts to form the ligamentum teres
3. Umbilical arteries constrict to form the medial umbilical ligaments
4. Within 10-15 hours after birth, the ductus arteriosus constricts to become the ligamentum arteriousum
5. Ductus venosus constricts to become the ligamentum venosum
6. Increased left atrial pressure and decreased right atrial pressure causes the foramen ovale to close. It comes the fossa ovalis.