Embryology 2 Flashcards
What is the two ways blood vessels develop
Vasculogenesis
Angiogenesis
What is the definition of Vasculogenesis
defined as the new formation of a primitive vascular network
What is the definition of angiogenesis
defined as the growth of new vessels from pre-existing blood vessels
What is the three main circulations
The cardinal
The vitelline
The umbilical
What is the aortic sac an extension of
the truncus arteriosus of primordial heart tube
Where does the first arteries appear in the embryo
right and left primitive aortae
What does each primitive aorta have
a ventral part (ventral aorta) and a dorsal part (dorsal aorta)
Where does the aortic branches arise from and what is this formed from
the aortic sac formed from the two ventral aorta partially fusing together
What is the two fates of these aortic branches
They either persist or degenerate
What is happening the same time at the aortic branches formation
Development of Pharyngeal arch arteries - future neck
when does the pharyngeal arches develop
4-5th week
What does each arch receive
Each arch receives its own nerve and artery = pharyngeal arteries
What does the pharyngeal arteries allow
communication with aortic branches
The joining of the pharyngeal arteries and the aortic branches from what
6 pairs of aortic arches
Where does the aortic arches all communicate and terminate
the 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.)
What is the fate of arch 3
Start of the internal carotid artery
= carotid arch
What does the 4th right arch form
the right subclavian vein
What does the 4th left arch form
constitutes the distal part of the aortic arch
What is the fate of the 5th arch
Never forms or forms incompletely then regresses
What is the fate of the 6th right arch
The proximal part of the6th right archpersists as the proximal part of the rightpulmonary artery
What is the fate of the 6th left arch
The6th left archgives off the leftpulmonary a.and forms the ductus arteriosus;
What is the fate of the ductus arteriosus within 1-3 months
the ductus is obliterated and becomes the ligamentum arteriosum
What is the two causes of great arteries anomalies
- either due to persistence of aortic arches that normally should regress
- regression of arches that normally shouldn’t
What causes an abnormal subclavian artery
with regression of the right aortic arch 4 and the right dorsal aorta, the rightsubclavian arteryhas an abnormal origin on the left side
What is the outcome of an aberrant subclavian artery
forces the right subclavian artery to cross the midline behind thetrachea and oesophagus, which may constrict these organs
What is the cause of a double aortic arch
occurs with the development of an abnormal right aortic arch in addition to the left aortic arch,
What does the double aortic arch encircle and what does the result in
forms a vascular ring around the trachea and esophagus, making it difficult to swallow or breathe
What is patent ductus afteriosus
a condition wherein theductus arteriosusfails to close afterbirth
What is patent ductus afteriosus commonly associated with
Maternal rubella infection
What can patent ductus afteriosus result in
Poor weight gain
Difficulty in breathing
What can an uncorrected PDA lead to with age
congestiveheart failure
What is coarctation of the aorta
a congenital condition wherein theaortais narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts
What are the two forms of coarctation of the aorta
Pre-ductal coarctation
post-ductal coarctation
What is the possible causes of the aorta constrict after birth
The ductus arteriosus has muscle tissue incorporated into the arch of the aorta, so when it DA contract after birth it constricts aorta
Genetic or environmental factors
What do the vitelline arteries supply in the embryo and the adult
Embryo - The yolk sac
Adult - The gut
What is the function of the viteline veins
drain blood from the yolk sac to the sinus venosus
What do the vitelline veins develop into
Portal vein
Hepatocardiac (liver to heart) part of inferior vena cava
Liver sinusoids
Superior mesenteric vein
What is the umbilical arteries before birth
Paired branches of the dorsal aorta to placenta
What is the fates of the proximal portion of the umbilical arteries after birth
Proximal portion persists as internal iliac and superior vesical branches (to urinary bladder)
What is the fate of the distal portion of the umbilical arteries after birth
degenerates to form obliterated umbilical arteries and forms medial umbilical ligaments
Where does the umbilical veins originate from
chorionic villi of placenta carrying oxygenated blood to the embryo
What is the function of the umbilical veins
carrying oxygenated blood to the embryo
What is the fate of the right umbilical vein
degenerates completely
What is the fate of the left umbilical vein
regresses and forms ligamentum teres (=round ligament) of adult liver
What is the fate of the ductus venosus
obliterates and forms ligamentum venosum
What allows oxygenated blood from the placenta to bypass the liver in the foetus
theductus venosus shunts a portion of the left umbilical vein blood flow directly to the inferior vena cava
What is the function of the cardinal veins
Carry the blood from the head and the lower body of the heart - drainage system of the embryo
What is the fate of the cardinal veins
Form vena caval (SVC and IVC) system by fusing among the veins
What is the ductus arteriosus function
A blood shunt passing the blood from the pulmonary artery to the aorta to bypass the lungs
Name four venous system abnormalities
Double IVC
Double SVC
Absence of IVC
Left SVC (normally connects to right atrium)
Where and when does the lymphatic system develop in the foetus
Develops at the end of sixth week around main veins
What is developed at the end of the embryonic period
6 primary lymph sacs (the lymph vessels join the lymph sac later)
What is three important structures in prenatal circulation
Ductus venosus (shunts left umbilical vein blood flow directly to IVC: allows oxygenated blood from the placenta to bypass the liver).
Oval foramen (allows blood to enter the leftatriumfrom the right atrium: allows blood to bypass the lungs).
Ductus arteriosus (allows blood that still escapes to the right ventricle to bypass thelungs).
What is the 3 changes to circulation postnatal
Ductus venosus becomes the ligamentum venosum of the liver
Oval foramen closes after birth by tissue proliferation and adhesion of septal structures
Ductus arteriosus obliterates to form ligamentum arteriosum
What causes patent ductus arteriosus
Failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs
Where does 90% of coarctation occur
opposite the Ductus Arteriosus (DA).
