Embryology 2 Flashcards
What are the two different blood vessel development methods?
Vasculogenesis
and Angiogenesis
Define Vasculogenesis
defined as the new formation of a primitive vascular network
Define Angiogenesis
defined as the growth of new vessels from pre-existing blood vessels
Where do the first arteries appear?
First arteries to appear in the embryo – right and left primitive aortae
What does each primitive aorta have?
Each primitive aorta has a ventral part (ventral aorta) and a dorsal part (dorsal aorta)
How do aortic arches form?
Pharyngeal arteries communicate with aortic branches; these now called aortic arches
How many aortic arches are formed when in communication with the dorsal aortae?
6 aortic arches
Where do the 6 pairs of aortic arches develop from?
Aortic branches and pharyngeal arch arteries
Where do the 6 pairs of aortic arches terminate at?
Dorsal aorta
What is the fate of arches 1 and 2?
The1stand2nd archesdisappear early, remnant of the 1st arch forms part of the maxillary artery (branch of external carotid a.)
*dont worry about maxillary
What is the fate of the 3rd arch?
The3rd aortic archconstitutes the commencement of theinternal carotid a., and is therefore named thecarotid arch
What is the fate of the left and right 4th arch? *important
The4th right archforms theright subclavian,
The 4th left arch constitutes thedistal part of aortic arch
What is the fate of arch 5?
The5th archeither never forms or forms incompletely and then regresses.
What is the fate of right arch 6?
The proximal part of the6th right archpersists as the proximal part of the rightpulmonary artery
What is the fate of left arch 6
The6th left archgives off the leftpulmonary a.and forms the ductus arteriosus; within 1–3 months, the ductus* is obliterated and becomes the ligamentum arteriosum
*important
Why do some great arteries anaomalies arise?
Most defects of the great arteries arise as a result of persistence of aortic arches that normally should regress or regression of arches that normally shouldn’t.
Define aberrant subclavian artery
with regression of the right aortic arch 4 and the right dorsal aorta, the rightsubclavian arterysometimes has an abnormal origin on the left side. To supply blood to the right arm, this forces the right subclavian artery to cross the midline behind thetrachea and oesophagus, which may constrict these organs, although usually with no clinical symptoms.
Describe a double aortic arch
occurs with the non-regression of the right aortic arch – ie., an abnormal right aortic arch in addition to the left aortic arch - forming a vascular ring around the trachea and oesophagus, which usually causes difficulty in breathing and swallowing.
What is a common anaomly associated with maternal rubella infection
patent ductus arteriosus
What is the cause of patent ductus arteriosus?
Cause – Failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs
Define what coarctation of aorta is?
Coarctation of the Aorta; a congenital condition wherein theaortais narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts
Which 3 embryonic circulations are present in the fetus?
Umbilical = placental Cardinal = rest of body Vitelline = yolk sac
What is the fate of umbilical arteries before birth?
Paired branches of the dorsal
aorta to placenta
What is the fate of umbilical arteries after birth?
After birth -
Proximal portion persists as internal iliac and superior vesical branches to urinary bladder
What is the fate of cardinal veins?
Main venous drainage system of the embryo
Form vena caval (SVC and IVC) system by anastomosis among the veins
How can double inferior vena cava arise?
At lumbar level arising from the persistence of the left sarcocardinal vein
How can absent inferior vena cava arise?
The lower half of the body is drained by the azygous vein which enters the superior vena cava. .
How many primary lymph sacs develop at the end of the embryonic peroid?
six
How many bypass shunts does the lung have before birth?
2
How many bypass shunts does the liver have before birth?
1
What are the 3 foetal circulation shunts?
Ductus venosus
Oval foramen
Ductus arteriosus
Describe the blood flow for ductus venosus and what its function
shunts left umbilical vein blood flow directly to IVC: allows oxygenated blood from the placenta to bypass the liver
Describe the blood flow for oval foramen and its function
allows blood to enter the leftatriumfrom the right atrium: allows blood to bypass the lungs
Describe the blood flow for ductus arteriosus and its function
allows blood that still escapes to the right ventricle to bypass thelungs
In terms of neonatal circulation changes after birth, what does the ductus venosus become?
becomes the ligamentum venosum of the liver
In terms of neonatal circulation changes after birth, what does the oval foramen become?
closes after birth by tissue proliferation and adhesion of septal structures -> fossa ovalis
In terms of neonatal circulation changes after birth, what does the ductus arteriosus become?
obliterates to form ligamentum arteriosum
In term of neonatal circulation changes after birth, what does the umbilical arteries become?
ligamentous - medial umbilical ligaments
