CVS embryology 1 and 2 Flashcards
the CVS is the first major system that functions in the embryo, when does it begin to work?
week 4
what is the importance of the early functioning of the CVS in embryology?
the embryo is rapidly growing and nutrition by diffusion alone is not sufficient to satisfy the growing embryo
describe what happens in CVS development in the 3rd week?
blood vessels ‘islands’ begin to appear in the yolk sac, allantois, connecting stalk, and chorion (these are called the cardiogenic field)
two heart tubes are formed from blood vessels in lateral plate splanchnic mesoderm
heart tubes fuse and join blood vessels in other areas to form primordial CVS
what does the parietal and fibrous pericardium from from?
somatic mesoderm
what does the visceral layer form from?
splanchnic mesoderm
what is the function of the foramen ovale?
to allow blood in the foetal heart to pass from right to left atrium so it does not pass the lung as it is non-functioning at this stage.
what is the fossa ovalis
a depression in the interatrial septum in the ADULT heart and is the remnant of the foramen ovale
where do the cusps, chordae tendineae and papillary muscles of the ATRIOVENTRICULAR valves develop from?
ventricular wall
why does the bulboventricular loop form?
growing tube becomes too large for the pericardium, this is caused by bulbous cordis and primitive ventricle becoming larger than the rest of primitive heart tube
in formation of the bulboventricular loop, which direction do the atria and ventricles move?
atria, posteriorly and superiorly
ventricles, left and inferiorly
what is the most common positional abnormality of the heart?
dextrocardia
Heart tube loops to left side (instead of right side), so ventricles come to lie facing the right (= dextro)
what does the aorticopulmonary septum split and cause the formation of?
divides bulbous cordis and truncus arteriosus into aorta and pulmonary trunk
what causes the partitioning of the primitive ventricle?
membranous ventricular septum which closes the interventricular foramen
formed when aorticopulmonary septum comes down and forms with ventricular septum and endocardial cusions
what are the first arteries to appear in the embryo?
right and left primitive aortae
what are the two methods by which blood vessels develop?
vasculogenesis - defined as the new formation of a primitive vascular network
angiogenesis - defined as the growth of new vessels from pre-existing blood vessels
how do most aortic arch abnormalities occur?
Most defects of the great arteries arise as a result of persistence of aortic arches that either normally should regress or regression of arches that normally shouldn’t.
eg. right subclavian artery
sometimes has abnormal origin on
the left may constrict trachea and oesophagus
what is double aortic arch abnormality?
occurs with the non-regression of the right aortic arch forming a vascular ring around the trachea and oesophagus, which usually causes difficulty in breathing and swallowing.
what is patent ductus arteriosus?
Common anomaly associated with maternal rubella infection in early pregnancy
caused by failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs
what is a consequence of patent ductus arteriosus?
An uncorrected PDA may lead to congestiveheart failurewith increasing age
what do the 3 embryonic vessels supply and what do they become in adulthood?
Vitelline vessels supply yolk sac, become adult gut vessels
Umbilical vessels supply placenta, become internal iliac
Cardinal vessels supply rest of body, become SVC & IVC
what are the 3 types of foetal shunt?
Ductus venosus - shunts blood in left umbilical vein into IVC: allows oxygenated blood from the placenta to bypass the liver.
Foramen ovale - shunts blood from rightatriumto left atrium: allows blood to bypass the lungs.
Ductus arteriosus - shunts blood from right ventricle and pulmonary arteries to aorta: allows blood to bypass the lungs.
what happens to the foetal shunts and umbilical arteries after birth?
Ductus venosus - ligamentum venosum of the liver
Foramen ovale closes after birth - fossa ovalis of the heart
Ductus arteriosus - ligamentum arteriosum between left pulmonary artery and aorta
Umbilical arteries - medial umbilical ligaments of the anterior abdominal wall
