Development of Arterial System

Question 1

How are the dorsal aortae formed?

Answer 1

bilateral angiogenic cell clusters coalesce and form a pair of longitudinal vessels (the
dorsal aortae)

Question 2

What do the paired dorsal aortae become? How does this compare to the paired aortic
arches?

Answer 2

One aorta caudally. Paired aortic arches stay paired

Question 3

Paired branchial arteries carry _______________.

Answer 3

Oxygenated blood to paired dorsal aortae

Question 4

What gives off an arterial branch to each pharyngeal pouch?

Answer 4

Aortic sac (most distal part of the truncus arteriosus)

Question 5

The aortic sac forms right and left horns as the truncus arteriosus divides into the
outflow tracts of the heart. What do the right and left horn become?

Answer 5

Right horn: brachiocephalic artery, Left horn: Proximal aortic arch

Question 6

How is the development of the aortic arches related to development of somites?

Answer 6

The sequence of development of the aortic arches can help depict age

Question 7

The branches from the aortic sac to the pharyngeal pouches are called _______. What
are they associated with ventrally and dorsally?

Answer 7

Aortic arches. Ventrally associated with aortic sac, Dorsally associated with dorsal
aortae

Question 8

In what sequence are the aortic arches formed?

Answer 8

Craniocaudal sequence, creating a “basket” of arteries around pharynx

Question 9

What do the 1st aortic arches become?

Answer 9

Small portion persists to become the maxillary artery

Question 10

What do the 2nd aortic arches become?

Answer 10

Small portions persist to become the hyoid and stapedial arteries

Question 11

What do the 3rd aortic arches become?

Answer 11

Become the common and proximal internal carotid arteries. Dorsal internal carotid
from dorsal aorta, external carotids branch from internal carotid

Question 12

Arches IV and VI undergo asymmetric remodeling. What do the left part and the right
part of the 4th aortic arch become?

Answer 12

Left: part of the arch of the aorta (btn. Carotid and sublcavian arteries). Right: most
proximal portion of subclavian artery

Question 13

From which artery does the 7th intersegmental artery branch from?

Answer 13

Right subclavian artery

Question 14

If the right dorsal aorta fails to obliterate, what anomaly do we have? What should it
have done?

Answer 14

Double aortic arch (vascular ring). The right dorsal aorta should have disconnected
from fused midline dorsal aorta and the right 6th arch.

Question 15

Abnormal obliteration of the R 4th arch and abnormal origin of the R subclavian artery
results in what?

Answer 15

Abnormal R subclavian crosses posterior to esophagus

Question 16

What is the final right subclavian from?

Answer 16

(1) R 4th aortic arch (2) R dorsal aorta (3) R 7th segmental artery

Question 17

What is the final aortic arch from?

Answer 17

(1) Truncus (2) L 4th aortic arch (3) L dorsal aorta

Question 18

What is the final left subclavian from?

Answer 18

(1) L 7th segmental artery

Question 19

What does the 5th aortic arch form?

Answer 19

The 5th aortic arch never forms or disappears quickly

Question 20

What do the 6th aortic arches form?

Answer 20

R: proximal right pulmonary artery, L: ductus arteriosus

Question 21

Summarize what aortic arches 1-6 form.

Answer 21

1 – maxillary artery, 2 – hyoid and stapedial arteries, 3 – carotids, 4- L: aortic arch, R:
subclavian artery, 5 – never forms!, 6 – L: ductus arteriosus, R: prox R pulmonary artery

Question 22

Why are the recurrent laryngeal nerves different on the right and left sides?

Answer 22

R: distal 6th aortic arch disappears – nerve moves cranially – loops around subclavian.
L: 6th aortic arch persists as ductus arteriosus – nerve loops around ductus arteriosus. This
happens since the nerves have to loop back up to innervate the larynx

Question 23

What are the three groups of arteries coming off the abdominal aorta?

Answer 23

Lateral branches (adrenal, renal, gonadal), body wall (intercostal, lumbar, extremities),
anterior branches (celiac, superior mesenteric, inferior mesenteric)

Question 24

The vitelline arteries fuse and form the arteries in the dorsal mesentery of the gut.
Which artery forms the foregut, which forms the midgut, and which forms the hindgut?

Answer 24

Celialc artery (foregut), superior mesenteric artery (midgut), inferior mesenteric artery
(hindgut)

Question 25

Because _______ , the path out of the RV is through the ductus arteriosus into the
descending aorta.

Answer 25

pulmonary artery resistance is high

Question 26

The umbilical vein is ____% saturated. It heads from the placenta into the fetus through
what progression?

Answer 26

80% saturated. Towards liver – ductus venosus – IVC – RA – foramen ovale – LA – LV
– aorta

Question 27

What % saturation is blood from the aorta in fetal circulation? Where does it flow
then?

Answer 27

58% saturated. Flows into the placenta via the umbilical arteries

Question 28

Where is there mixing of saturated and unsaturated blood?

Answer 28

In the liver, in the IVC, in the RA, in the LA, and at the entrance of the ductus
arteriosus into the aorta

Question 29

What is the initial event in transitional circulation?

Answer 29

Initial event that reverses the shunts is a fall in pulmonary resistance (allows blood to
start circulating through the lung)

Question 30

Increased pulmonary flow _______ . Decreased flow from umbilical vein _______.

Answer 30

Increases pressure in the LA. Decreases pressure in the RA

Question 31

What does the first breath do?

Answer 31

Presses the septum primum against the septum secundum. Increased LA pressure and
decreased RA pressure functionally close the foramen ovale

Question 32

What is contraction of the muscular wall of the ductus arteriosus after birth mediated
by?

Answer 32

Bradykinin

Question 33

If a patient has a ductus dependent lesion, what do we give them right after birth?

Answer 33

Prostaglandin E1 to prevent the contraction of the muscular wall of the ductus
arteriosus

Question 34

How can we access the IVC in an umbilical vein catheter?

Answer 34

Pass catheter via ductus venosus