CVS Embryology 2 Flashcards
What are the first arteries to appear in the heart?
right and left primitive aortae. each primitive aortae has a ventral aorta and a dorsal aorta.
How is the aortic sac formed?
becomes an extension of the truncus arteriosus anteriorly. its the fusion of the 2 ventral aorta
When are aortic arches formed and how many?
4th and 5th weeks. 6 arches from left and right ventral aortic sac. arch to the left and right dorsal aorta
what happens to the 1st and 2nd arches?
dissapear in early development
What happens to the 3rd arches?
becomes carotid artery on left and right side
What happens to the 4th arches?
on right, forms right subclavian artery.
on left, forms aortic arch
What happens to the 5th arches?
dissapears
What happens to the 6th arches?
6th right forms right pulmonary artery.
6th left forms left pulmonary artery and ductus arteriosus
What is the function of the ductus arteriosus?
bypasses blood from pulmonary arteries directly into aorta, as lung isn’t functioning yet.
What defects can occur with development of the arteries? (4)
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
What is PDA?
patent ductus arteriosus. doesnt become ligamentous due to IRDS. needs correcting or may lead to heart failure with age
What are the 6 inflow tracts coming into the sinus venosus?
sinus venosus is split in 2 - right and left.
outer are common cardinal veins
midde are umbilical veins
inner are vitelline veins
What is the purpose and fate of umbilical vessels?
supply placenta. when broken down, become internal iliac arteries and veins in adult
What happens to the sinus venosus outflow tracts?
left veins break down and form left horn. right horn loses umbilical vein, and remains with common cardinal vein and vicelline vein.
What is the fate of the remaining sinus venosus outflow tracts?
left horn becomes coronary sinus
common cardinal vein becomes superior vena cava
vicelline vein becomes inferior vena cava
How is the lymphatic system developed and when?
6 primary lymph sacs form at the end of the embryonic period. lymph vessels join in later life
How is the thoracic duct formed?
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
Where do umbilical arteries arise from?
1 from each internal iliac artery - left and right
What do umbilical arteries do?
carry blood through the umbilical cord to the placenta, where it picks up O2 and nutrients, and releases Co2 and waste.
How is highly oxygenated blood brought back into the baby’s circulation?
through the umbilicus, through an umbilical vein which goes through the umbilical cord.
What happens to blood brought through umbilical vein?
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.
What are the 3 foetal circulation shunts?
ductus venosus
ductus arteriosus
foramen ovale
What is the fate of foetal circulation shunts after birth?
ductus venosus - ligamentum venosum
ductus arteriosus - ligamentum arteriosum
foramen ovale - fossa ovalis
What is the fate of umbilical arteries?
become ligamentous. lay on anterior abdominal wall as medial umbilical ligaments.
