CVS Embryology 2

Question 1

What are the first arteries to appear in the heart?

Answer 1

right and left primitive aortae. each primitive aortae has a ventral aorta and a dorsal aorta.

Question 2

How is the aortic sac formed?

Answer 2

becomes an extension of the truncus arteriosus anteriorly. its the fusion of the 2 ventral aorta

Question 3

When are aortic arches formed and how many?

Answer 3

4th and 5th weeks. 6 arches from left and right ventral aortic sac. arch to the left and right dorsal aorta

Question 4

what happens to the 1st and 2nd arches?

Answer 4

dissapear in early development

Question 5

What happens to the 3rd arches?

Answer 5

becomes carotid artery on left and right side

Question 6

What happens to the 4th arches?

Answer 6

on right, forms right subclavian artery.
on left, forms aortic arch

Question 7

What happens to the 5th arches?

Answer 7

dissapears

Question 8

What happens to the 6th arches?

Answer 8

6th right forms right pulmonary artery.
6th left forms left pulmonary artery and ductus arteriosus

Question 9

What is the function of the ductus arteriosus?

Answer 9

bypasses blood from pulmonary arteries directly into aorta, as lung isn’t functioning yet.

Question 10

What defects can occur with development of the arteries? (4)

Answer 10

right subclavian could come off left arch - constrict oesophagus or trachea

double aortic arch from 4th arch. can wrap around oesophagus and trachea - difficulty breathing and swallowing. worse than above

PDA

coarctation of aorta

Question 11

What is PDA?

Answer 11

patent ductus arteriosus. doesnt become ligamentous due to IRDS. needs correcting or may lead to heart failure with age

Question 12

What are the 6 inflow tracts coming into the sinus venosus?

Answer 12

sinus venosus is split in 2 - right and left.
outer are common cardinal veins
midde are umbilical veins
inner are vitelline veins

Question 13

What is the purpose and fate of umbilical vessels?

Answer 13

supply placenta. when broken down, become internal iliac arteries and veins in adult

Question 14

What happens to the sinus venosus outflow tracts?

Answer 14

left veins break down and form left horn. right horn loses umbilical vein, and remains with common cardinal vein and vicelline vein.

Question 15

What is the fate of the remaining sinus venosus outflow tracts?

Answer 15

left horn becomes coronary sinus
common cardinal vein becomes superior vena cava
vicelline vein becomes inferior vena cava

Question 16

How is the lymphatic system developed and when?

Answer 16

6 primary lymph sacs form at the end of the embryonic period. lymph vessels join in later life

Question 17

How is the thoracic duct formed?

Answer 17

2 vessels laying anteriorly to aorta, which become left and right embryonic thoracic duct.

left one becomes upper 1/3rd of adult thoracic duct
right one becomes lower 2/3rds of adult thoracic duct

Question 18

Where do umbilical arteries arise from?

Answer 18

1 from each internal iliac artery - left and right

Question 19

What do umbilical arteries do?

Answer 19

carry blood through the umbilical cord to the placenta, where it picks up O2 and nutrients, and releases Co2 and waste.

Question 20

How is highly oxygenated blood brought back into the baby’s circulation?

Answer 20

through the umbilicus, through an umbilical vein which goes through the umbilical cord.

Question 21

What happens to blood brought through umbilical vein?

Answer 21

splits into:
hepatic portal vein, taking highly oxygenated blood to liver(requirement increases with gestation), and ductus venosus, back to heart

ductus venosus - shunt for blood to enter inferor vena cava back to heart. IVC has deoxygenated blood from foetus’s lower limbs. forms mix of O2 and deO2 blood.

Question 22

What are the 3 foetal circulation shunts?

Answer 22

ductus venosus
ductus arteriosus
foramen ovale

Question 23

What is the fate of foetal circulation shunts after birth?

Answer 23

ductus venosus - ligamentum venosum
ductus arteriosus - ligamentum arteriosum
foramen ovale - fossa ovalis

Question 24

What is the fate of umbilical arteries?

Answer 24

become ligamentous. lay on anterior abdominal wall as medial umbilical ligaments.