Embryology 2 Flashcards
define vasculogenesis
the new formation of a primitive vascular network
define angiogenesis
growth of new vessels from pre-existing blood vessels
fate of the 1st and 2nd aortic arches
become the maxillary arteries
fate of the third aortic arch
Common carotid and first part of internal carotid arteries
fate of the 4th aortic arch on the left side
arch of the aorta (Distal portion)
fate of the 4th aortic arch on the right side
Right subclavian artery (proximal portion)
fate of the 6th aortic arch on the right side
Becomes right pulmonary artery
fate of the 6th aortic arch on the left side
Becomes left pulmonary artery and ductus arteriosus
what happens to the 5th aortic arch
either never forms or form incompletely and then disappears
when does the lymphatic system develop
at the end of the 6th week develops around main veins
what are the first arteries to appear in the embryo?
left and right primitive aortae - each primitive aortae has a ventral and dorsal part
after the fusion of 2 endothelial tubes… the 2 ventral aortae partially fuse to from what?
aortic sac
how many aortic arch pairs are formed
6
what do most defects of the great arteries arise as a result of? (2)
persistence of aortic arches that normally should regress or regression of arches that normally shouldn’t
what is aberrant (abnormal) subclavian artery
a rare congenital anomaly that usually does not produce symptoms vascular anomaly of the aortic arch right subclavian artery 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 the trachea and oesophagus, which may constrict these organs
double aortic arch - watch out for in OSPE
another congenital aortic arch anomaly occurs with the development of 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 breathing and swallowing.
Patent ductus anteriosus PDA
ductus arteriosus fails to close after birth Early symptoms are uncommon but in the first year of life include increased ‘work of breathing’ and poor weight gain. An uncorrected PDA may lead to congestive heart failure with increasing age. females > males common link with maternal rubella infection can be genetic or incidental
coarctation of the aorta
congenital condition aorta is narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression- connects pulmonary artery with aorta) inserts. The word “coarctation” means narrowing. Coarctations are most common in the aortic arch. Can be proximal to ductus arteriosus (preductal) or distal to it (postductal). (Co = Coarctation site).
what are the 3 major areas of embryo
yolk sac placenta aortic arch area
names of circulations for:- 1. yolk sac 2. placental 3. rest of body
- vitelline 2. umbilical 3. cardinal
what is the fate of the vitelline arteries in embryo vs adult?
In embryo vitelline arteries supply the yolk sac In adult are represented by arteries to the foregut, midgut & hindgut
umbilical arteries before and after birth
Before birth:- Paired branches of the dorsal aorta to placenta After birth:- Proximal portion persists as internal iliac and superior vesical branches to urinary bladder
embryonic venous system
Vitelline veins – Carrying blood from the yolk sac to the sinus venosus Umbilical veins – originate from chorionic villi of placenta carrying oxygenated blood to the embryo Cardinal veins – draining the body of embryo
where do vitelline, umbilical and cardinal veins drain to?
the right atrium
Discuss cardinal veins
Main venous drainage system of the embryo - carry the blood from the head and the lower body into the heart System consists of – anterior, posterior & common cardinal veins draining to sinus venosus Form vena cava (SVC and IVC) system by anastomosis among the veins
Venous system abnormalities (4)
double IVC abscence of IVC left SVC double SVC
Discuss the development of the lymphatic system
develops at the end of week 6 there are 6 primary lymph sacs at the end of embyronic period lymphatic vessels/channel will join the lymph sacs later
why do you no longer need to shunt blood through the heart after a child is born?
because the child can breath so pulmonary circulation kicks in ductus arteriosus is shut off so blood doesn’t move from RA to LA anymore
what is good respiration in neonate dependent on?
a normal circulatory transition at birth (placental circulation to pulmonary circulation)
what does the ductus venosus do pre birth and why is it shut after birth?
pre birth:- it shunts left umbilical vein blood flow directly to IVC which allows oxygenated blood from the placenta to bypass the liver When you are born you use your liver so this duct that bypassed the liver is shut off.
oval foramen pre and post birth
before it allows blood to enter the LA from the RA which allows blood to bypass the lungs don’t need this bypass after birth as lungs should be fully functioning
what is the ductus arteriosus and what does it bypass
a blood vessel connecting the main pulmonary artery to the proximal descending aorta. It allows most of the blood from the right ventricle to bypass the foetus’s fluid-filled non-functioning lungs.
state the pathway of blood from aorta to umbilical vein in foetus
Aorta descending aorta abdominal aorta common iliac artery umbilical arteries placenta umbilical vein
what happens to foramen ovale, ductus venosus and ductus arteriosus at birth?
they are all shut off
what does the ductus venosus become
it constricts and becomes solid the ligamentum venosum of the liver
what does the ductus arteriosus become
it constricts and becomes solid ligamentum arteriosum (small ligament)
Cause of patent ductus arteriosus
Failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs
