embryology of the cvs Flashcards
what are the four stages of heart development?
primitive heart tube
heart looping
atrial and ventricular septation
outflow tract septation
what forms the circulatory system in the 3rd week
lateral plate splanchnic mesoderm
what forms two primitive heart tubes?
Angiogenic cell islands collect in
the lateral plate splanchnic mesoderm, move towards the midline and coalesce
whats the first major system to function in the embryo?
cvs
when does the primordial heart start to function?
4th week
where do blood vessels start to appear?
wall of yolk sac, allantois, connecting stalk and chorion
what are angioblastic cords?
paired endothelial strands
when does the angioblastic cords form?
3rd week
what canalises to form heart tubes?
angioblastic cords
what forms primordial cvs?
Tubular heart joins blood vessels in other areas
what is the pericardium derived from?
intra-embryonic coelom
whats the visceral layer of serous pericardium derived from?
splanchnic mesoderm
what are the terms in a fused primitive heart tube
truncus arteriosus bulbus cordis ventrical atrium sinus venosus
how many horns does sinus venosus have?
2
how does each horn of sinus venosus get venous blood?
Each horn gets venous blood from:
yolk sac (=vitelline v.)
placenta (=umbilical v.)
body of the embryo (=common cardinal v.)
where does aortic arch arise from?
aortic sac
where does the aortic arch terminate?
dorsal aorta
what forms the bulboventricular loop?
Bulbus cordis and ventricle
what way does the heart loop to?
left
what is dextrocardia?
when heart loops to right side of body
whats the function of the Endocardial cushion formation
separates right atrium + ventricle from
left atrium +ventricle to form L&R AV canals
whats the funtion of the Septum formation
separates right atrium from left atrium
+ right ventricle from left ventricle
when does the partitioning of primitive atrium into left and right atria start?
end of weeek 4
what are the two septum and two foramina developings during the partition?
) Septum primum & foramen primum
2) Septum secundum & foramen secundum
what is the septum primum?
the sickle shaped crest that grows from roof of atrium.
this growth generates foramen primum
where is the foramen secundum formed?
upper end of the septum primum
where does the septum secundum fold on to?
) forms on the right of septum primum.
where does the septum scandium grow down to
grows down and overlaps the foramen secundum
where does foramen secundum open in ?
septum primum
where doesforamen ovule open in ?
septum secundum
whats the role of oval foramen before birth?
Allows most of the blood to pass from the right atrium to the left atrium (non functioning lung)
Prevents the passage of blood in the opposite direction
whats the role of oval foramen after birth?
Normally closes (increased pulmonary blood flow and shift of pressure to the left atrium)
Septum primum (= valve of oval foramen) fuses with the septum secundum
Oval fossa (fossa ovalis) of adult heart is a remnant of foetal oval foramen
Non closure results in Atrial Septal Defect (ASD) – “Hole in the heart”
what are the four types of atrial septal defects?
Foramen secundum defect
Endocardial cushion defect with foramen primum defect
Sinus venosus defect
Common atrium
The first two types are more common
which gender is more likely to get ASD
females
what is the opening called in muscular ventricular septum?
interventricular foramen
what fuses to form membranous inter ventricular septum?
Bottom of spiral aorticopulmonary septum fuses with muscular ventricular septum
what divides the bulbis cordis and truncus arteriosus
aorticopulmonary septum
whats the most common congenital heart disease?
Ventricular Septal Defect (VSD)
what gender is Ventricular Septal Defect (VSD) more common?
males
when does the pacemaker develop?
week 5
wheres the adult location of the pacemaker (SA node)
High in the right atrium near the entrance of the SVC
what does the aortic sac develop into?
aortic arches
what does the bulbus cordis develop into?
right ventricle
parts of the outflow tracts
what does the primitive ventricle develop into?
left ventricle
what does the primitive atrium develop into?
parts of right and left atria
what does the sinus venosus develop into?
superior vena cava
right atrium
what are the reasons for congenital heart disease?
Rubella infection in pregnancy (PDA)
Maternal alcohol abuse (septal defects)
Maternal drug treatment and radiation
Genetic - 8%
Chromosomal – 2% (Down’s and Turner’s syndrome)
what is the cause of transposition of great vessels?
) Failure of aorticopulmonary septum to take a spiral course
- 2) Defective migration of neural crest cells
Common cause of cyanotic disease in newborn infants
Associated with ASD and VSD
Permit exchange of systemic and pulmonary circulation
whats the tetralogy of fallot
Pulmonary stenosis (obstruction of right ventricular outflow)
Ventricular septal defect (VSD)
Dextroposition of aorta (“overriding” aorta)
Right ventricular hypertrophy
what is vasculogenesis?
defined as the new formation of a primitive vascular network
whats angiogenesis?
defined as the growth of new vessels from pre-existing blood vessels
true or false: each primitive aorta l part has a ventra
false it has dorsal as well
After the fusion of two endothelial tubes the two ventral aortae partially fuse to form…
aortic sac
what do aortic branches arise from?
aortic sac
when does the pharyngeal arches develop?
4th and 5th week
do each arch receive artery? its own nerve and
yes
when is it called aortic arches?
when Pharyngeal arteries communicate with aortic branches
how many arches are formed on each side?
6 aortic arches
where do aortic arches terminate?
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
what is the fate of arch 3?
The3rd aortic archconstitutes the commencement of theinternal carotid a., and is therefore named thecarotid arch
what is the fate of arch 4
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 arch 6
The proximal part of the6th right archpersists as the proximal part of the rightpulmonary artery
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
when does aberrant subclavian artery occur?
with regression of the right aortic arch 4 and the right dorsal aorta, the rightsubclavian arteryhas 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.
when does double aortic arch occur?
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 dificutly breathing and swallowing.
when does patent ductus arteriosus occur?
); a condition wherein theductus arteriosusfails to close afterbirth.
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 congestiveheart failurewith increasing age.
when does coarctation of the aorta occur?
a congenital condition wherein theaortais narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts. The word “coarctation” means narrowing.Coarctationsare most common in theaorticarch. Can be proximal to ductus arteriosus (preductal) or distal to it (postductal). (Co = Coarctation site).
what supplies the placental circulation?
left umbilical vein
umbilical artery
what supplies the vitelline circulation?
vitelline vein
vitelline artery
what are the three major areas of the embryo?
vitelline = yolk sac umbilical = placental cardinal = rest of body
whats the fate of umbilical arteries before birth?
Paired branches of the dorsal
aorta to placenta
whats the fate of umbilical arteries after birth?
Proximal portion persists as internal iliac and superior vesical branches to urinary bladder
whats the function of vitelline veins?
Carrying blood from the yolk sac to the sinus venosus
whats the function of umbillical veins?
originate from chorionic villi of placenta carrying oxygenated blood to the embryo
whats the function of cardinal veins?
draining the body of embryo
where does vitelline, umbilical and cardinal veins drain to?
right atrium
when does the lymphatic system develop
end of 6th week around the main veins
when do the 6 lymph sacs develop?
end of embryonic period
do lymphatic vessels join lymph sacs?
yes they do, but later
what are the three foetal and neonatal circulations?
Ductus venosus
Oval foramen
Ductus arteriosus
whats the function of the Ductus venosus
shunts left umbilical vein blood flow directly to IVC: allows oxygenated blood from the placenta to bypass the liver
whats the function of the oval foramem
allows blood to enter the leftatriumfrom the right atrium: allows blood to bypass the lungs
whats the function of ductus arteriosus?
allows blood that still escapes to the right ventricle to bypass thelungs
what becomes ligamentum venosum of the liver?
ductus venosus
what closes after birth by tissue proliferation and adhesion of septal structures?
oval foramen
what obliterates to form ligamentum arteriosum
ductus arteriosus
which gender is patent ducts arteriosus more common in?
females
whats the cause of patent ductus arteriosus?
Failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs
whats the cause of coarctation of aorta?
Incorporation of muscle tissue of DA into arch of aorta (during development). When DA contracts after birth, part of the arch also constricts
Genetic / environmental factors
