Lecture 19: Embryonic Cardiovascular System Flashcards
cardiogenic mesoderm of heart primordium
epiblast cells ahead of precordal plate that migrate through primitive groove as mesoderm forms, and will become heart
angioblastic cords
pairs of vessels that will make pair of aorta and then fuse to become single aorta
where does heart begin in fetus?
above chest
what comes down to chest during folding
cardiogenic mesoderm, pericardial sac, septum transversum
why no circulation through lungs in fetus
because lungs haven’t formed and no air/oxygen in the lungs, so don’t need blood circulation
therefore blood pumps out of aortic arches, oxygenated blood is used by fetus’s tissues, and then carried back to heart by vein
cranial to caudal, parts of embryonic single heart tube
aortic sac, truncus arteriosis, bulbus cordis, primitive ventricle, primitive atrium, sinus venosus
where veins entering into heart tube go through
from ylk sac, through sinus venosus, to embryonic heart
why single heart tube folding occurs
genes tell heart to fold, and cells proliferate more rapidly on 1 side causing cranial fold
fetal heart circulation
blood goes into sinus spinosis - ventricle - bulbus cordis - aortic sac - 1st pharyngeal arch artery
endocardial cushions
2 mounds of tissue that separate primordial atria from ventricle and divide heart into R and L atrio-ventricular canals
also play role in AV valve formation (mitral, tricuspid)
papillary muscles
hold tissue strands growing from walls of ventricles to endocardial cushion in places
will become the AV valves
interventricular septum
separates R and L ventricles
muscular, membranous parts
muscular part of interventricular septum
ingrowth of cardiac mesoderm that grows toward cardiac cushions
membranous interventricular septum
tissue that grows from endocardial cushions and meets up with muscular part of septum
ventriculo septal defect
in membranous portion of interventricular septum most likely
when thin tissue there doesn’t grow closed properly and so child needs surgery to close it
leaflets that partition right and left primitive atrium
septum primum, septum secundum
septum primum
starts from posterior wall of primitive atrium, grows toward endocardial cushion; as grows, little fenestrations within so blood can get from R to L atria
includes foramen primum and foramen secundum
foramen primum
little space that remains in septum primum so blood can pass from R to L atria; eventually is fused/obligerated
foramen secundum
growth of fenestrations in septum primum causes this opening
it remains into development of heart, doesn’t get obliterated - becomes the foramen ovale
foramen ovale
remnant of the septum secundum
passage between 2 atrial cavities through which blood flows from right to left atrium
septum secundum
second septum in atria
is anterior to septum primum
leaves opening in development of heart so blood can flow from R to L atria through foramen ovale
structures associated with primitive atria
septum primum, foramen primum, septum secundum, foramen ovale
where a stroke in a young person could go across
foramen ovale
foramen ovale function
right to left shunt
allows blood to bypass fetal lungs
closes after birth when pulmonary vascular resistance decreases and left atrial pressure increases
conotruncal ridges (bulbar, truncal)
form in truncus arteirosis and part of bulbus cordis
aorticopulmonary septum
formed by ridges of right superior truncus and left inferior truncus growing toward the aortic sac, swelling and twisting around each other
meets interventricular septum
divides truncus into aorta and pulmonary artery
aorta v pulmonary artery re: outflow
aorta- L ventricular outflow tract
pulmonary artery- R ventricular outflow tract
order of aorta/pulmonary trunk and why
pulmonary trunk- more ventral, aorta- more dorsal, because of spiraling
2 types of valves
semilunar, atrioventricular
semilunar valves
aortic and pulmonic
aortic: separates aorta from left ventricle
pulmonic: separates arteries from right ventricle
derivation of semilunar valves
swellings in subendocardial region
usually 3 cusps/seminlunar portions, although have a bicuspid aortic valve
types of AV valves
tricuspid: right atria to right ventricle
mitral: left atria to left ventricle
derivation of atrioventricular valves
proliferation of tissue around endocardial cushions/A-V canals
dorsal aorta
initially, pair of tubes; fuses to form single dorsal aorta; connects w/ aortic arches; aortic arches connect to aortic sac in primitive heart tube
paired dorsal aortae
each paired arch is assocaited with a pharyngeal arch; they connect to aortic sac
how many aortic arches develop
6; do not all develop at the same time
what is descending aorta result of
fused dorsal aorta
pharyngeal arches
pair to form aortic arch
left 4th pharyngeal arch
becomes much of aortic arch
left 6th pharyngeal arch
becomes left pulmonary artery and ductus ateriosis
ductus arteriosis
derivative of left 6th pharyngeal arch
shunt in fetal pulmonary artery that shunts blood through to aorta instead of going to lungs
3 pairs of primitive veins
all empty into sinus vinosus; will contribute to vena cava and primitive blood return to heart
vitelline veins- drain yolk sac (low O2)
umbilical veins- form placenta (high O2)
common cardinal veins- from body of embryo (low O2)
what happens to R umbilical vein?
it disappears
what carries blood from mom to fetus?
L umbilical vein
only vein in umbilical cord
has ductus venosus shunt to shunt blood back to heart, doesn’t go through liver like normally does
derivatives of superior vena cava
right anterior cardinal vein, right common cardinal vein
tetrology of fallot components
frequent abnormality
due to unequal partitioning of truncus arteriosis from spinous arteriosis
4 cardiovascular alterations:
- pulmonary stenosis (narrow right ventricular outflow region)
- ventricular septal defect
- overriding aorta
- right ventricular hypertrophy
do embryonic umbilical arteries have high or low O2 content?
they have the highest O2 content of the embryonic veins
