embryology Flashcards
what are the main stages of cardiovascular embryology (4)
development of primitive heart tube
looping of the heart tube
atrial/ventricle separation
outflow tract development
what forms the circulatory system
the lateral plate splanich mesoderm
when dose the primordial heart start to function
at 4 weeks
where do blood vessels first aperar
yolk sac, allantois, connecting stalk and chiron
what forms heart tubes
angioblastic cords
what are angioblastic cords
paired endothelial strands
what do heart tubes form into
the primordial cardivascualr system
what dose the somatic mesoderm form
the parieral layer of the serious pericardium
the fibrous pericardium
what forms the visceral layer of the serous pericardium
the splenic mesoderm
what happens between day 18 and 22 of gestation
fusion of the heart tubes
what are the 5 parts of the fused primitive heart tube - from top to bottom
truncus arteriosus - the wings of the chicken
bulbs cordis
ventricle
atrium
sinus venosus (right and left horns) - the chicken legs of the heart
what is the form and function of the truncus arteriosus
the most superior part of the fused heart tubes
once the primitive heart tube folds this then divides to form the aorta and the pulmonary trunk
what forms at of the top of the truncus arteriosus
the aortic sac with its left and right horns
what forms out of the aoric sack
6 arches out of each horn
what do the right 6 arches out of the igh horn of the artic sac terminate
the right dorsal aorta
what do the left 6 arches out of the left horn of the artic sac terminate
the left dorsal aorta
what form the bulboventricle loop - how
the blulbus cordis and ventricle
they grow faster than the rest of the fused primitive heart tube
what dose the bulbbus cordis form
the bulboventricle loop
it becomes mainly part of the right ventricle
what dose the sinus venosus become
the ends of all the major veins heading to the heart
what is the structure of the sinus venosus what comes to it
it has two horns (left and right)
and each horn has 3 veins - vitelline, umbilical , common cardinal
what vein supplies the body of the embryo
the common cardinal
what vein supplies the youlk sack
viteline
—-where all the vitamins go
what vein supplies the placenta
umbilical
what wa does the hear normally loop
to the right
when dose partitioning of the primordiaal heart (atria/ventrical seperation) being
around the 27th - 37th days
what 2 things form during th partioting of the primitve heart
endocardial cushin formation
septum formation
what dose the septum formation lead to
the separation of the right side of the heart from the left side of the heart
what does the endocardial cushion formation lead to
the rough separation of the atrium and ventricles
what happens in the first step in the separation of the primitive atrium
septum primum is formed - with the space below being called the foramen primum
what happens after the first part of the septum foramen is formed
the 2nd part of the septum primum forms with the gap above and below
what forms above the septum primum
the foramen secundum
what does the lower septum primum fuse with
the dorsal endocardial cushion
what forms next
the septum secundum beside both septum primum
what dose the septum primum become
the door
with the septum secundum becoming the walls
what is the final foramen left before birth
the foramen ovale
where is the open foramen ovale located
between the anterior side of the septum primum and septum secundum
what is the fossa ovalis a remittent of
the foetal ovale foramen
what happens if the oval foramen dosent close
it leads to ASD atrial septal defect
what are the 2 most common forms of clinically significant atrial septal defect (ASD)
foramen secundum defect
endocardial cushion defect with septum primum defect
how does the primitive partitioning of the ventricles occur
muscular ventricular forms (opening above is called the intraventricular foramen)
the aorticopulmonary septum forms - the bottom fuses with the muscular ventricle septum
what is the function of the membranous ventricular septum
to fuses the muscular ventricular septum ant the aortopulmonary septum
and close the interventricular foramen
what is the function of the aorticopulmonary septum
to divide the bulbus cordis and truncus arteriosus (top of bulbus cordis) into the aorta and pulmonary trunk
what contributes to the membranous interventricular septum
the endocardial cushion
how dose the aorticopulmonary septum divide the bulbus cordis and truncus arteriosus
why twisting up the centre
what type of defect occurs when the partitioning of the primitive ventricles goes wrong
VSD - ventricular septal defect
what happens to small VSDs (ventricular septal defects)
they close on their own
what is the most common type of VSD
membranous types - effecting the intraventricular septum
when does the SA node develop
week 5
where is the location of the adult SA node
high in the right atrium
near entrance to SVC
how does cot death occur (sudden infant death syndrome - SIDS)
cased by abnormal conducting tissues
what is the aetiology of congenital heart disease
it is multifactorial
what factors contribute to congenital heart disease - 5
rubella infection In pregnancy (PDA)
maternal alcohol abuse - septal defects
maternal drug treatment and radiation
genetics
chromosomes
what is the name of the disease that has 4 cardiac defects
tetralogy of fallot
what are the 4 cardiac defects for the teratology of fallot
pulmonary stenosis
ventricular septal defect (VSD)
dextroposition of aorta
right ventricular hypertrophy
what two causes lead to the transposition of the great vessels
failure of the aorticopulmonary septum to spiral
defective migration of neural crest cells
what are neural crest cells
cells that are pinched of from the ectoderm during the formation of the neural tube, these then form complex structures often related to the nervous system
what causes the teratology of fallot
Unequal division of the conus arteriosus (cone shaped structure that the pulmonary trunk forms out of) due to anterior displacement of aorticopulmonary septum
what is vasculogenesis
the NEW formation of a primitive vascular network
what is angiogenesis
defined as the growth of new vessels from pre-existing blood vessels
when do the pharyngeal arches develop
during week 4 and 5
what do the pharyngeal arches become
the neck
what forms around the pharyngeal arches
the 6 aortic arches on either side
what is the fate of arches 1 and 2
disappear early
1st arch remnants forms maxillary artery (side of the face)
what is the fate of the 3rd arch
it becomes the start of the internal carotid artery
what is the fate of the 4th RIGHT arch
it forms the right subclavian
what is the fate of the 4th LEFT arch
the distal part of the aortic arch
what is the fate of the 5th arch
forms incompletely then regresses
forms nothing
what is the fate of the 6th RIGHT arch
it become the proximal (closer to centre) part of the right pulmonary artery
what is the fate of the 6th LEFT arch
it becomes the left pulmonary artery
and the ductus arteriosus
what is the ductus arteriosus
a normal blood vessel that connects two major arteries — the aorta and the pulmonary artery
what does the ductus arteriosum become - when
it closes and becomes the ligamentum arteriousum after 1- 3 months
what is the most common form of great artery defects
defects because there regression of arteries where there shouldn’t
or some arteries that should regress but don’t
what occurs to from the aberrant subclavian artery defect
the right subclavian forms on the left side of the aortic arch
it has to cross the midline behind the trachea and oesophagus - leading to constriction of these organs - no clinical symptoms
what occurs in the formation of the double aortic arch
an abnormal right aortic arch is also formed, leads to the formation of a vascular ring around the trachea and oesophagus - difficulty breathing and swallowing
what is PDA ( patent ductus arteriosus)
when the ductus arteriosus fails to close after birth and regress to form ligament atreriosum - uncorrected leads to hear failure when older
coarctation of the aorta
the aorta is narrow - often proximal or distal to the ductus arteriosum ( liganetum arteriousum)
what do the vitelline arteries supply
the yolk sack
what do the vitelline arteries become in adult hood
the arteries in the foregut, midgut and hindgut
what is the fate of umbilical arteries before birth
paired branches of the dorsal aorta to the placenta
after birth what is the fate of the umbilical arteries
the proximal portion becomes the vessels to the bladder and become the internal iliac (terminal branch in the pelvis)
what is the function of the vitelline veins
carrying blood from the yolk sac to the sinus venosum
what is the function of the umbilical veins - from where
originate from the chorionic villi of placenta
carrying OXYGENATED BLOOD to the embryo
what is the function of the cardinal veins of the embryo
draining the body of the embryo
what do the cardinal veins form
the vena cava - IVC and SVC by anastomosis (connection between tubes)
what are some venous abnormalities (4)
double IVC
absence of IVC
left SVC
double SVC
when and where does the lymphatic system begin to form
develops at the end of the 6th week
6 lymph sacs develop around the main veins - and lymphatic vessels join them up later
what are the 3 important pieces of transitional circulation
ductus venosus
oval foramen
ductus arteriosus
what is the function of the ductus venosus
to shunt left umbilical vein blood flow directly to the IVC - allows O2 blood from the placenta to bypass the liver
what is the function of the ductus arteriosus
allows blood that escapes to the right ventricle to bypass the lungs
what is the function of the oval foramen
allows blood to enter the left atrium from the right atrium - bypass the lungs
what does the ductus venosus become after birth
the ligamentum venosum of the liver
how does the oval foramen close
by tissue proliferation and adhesion of the septal structures
