Lecture 19: The Heart Flashcards
where is cardiogenic mesoderm located
cranially to oropharyngeal membrane
what eventually engulfs the heart
pericardial coelom
what forms the initial artery/vein system
blood islands coalescing
where do vitelline arteries and veins empty
caudal end of heart tube
how is blood initially pumped to the body
through a single tube
what comprises the primitive heart tube
1) aortic sac
2) truncus arteriosis
3) bulbus cordis
4) primitive ventricle
5) primitive atrium
6) sinus venosus
formation of the AV septum
dorsal AV cushion and ventral AV cushion approach each other
what doe the AV septum partition
the AV canal into the R AV canal and L AV canal
formation of the IV septum
muscular IV septum develops in midline on floor of ventricle (from cardiac mesoderm) and grows toward fused AV cushion
Membranous IV semptum from bulbar ridge and AV cushions also grows
difference in initial vs end IV septum
initially, foramen in free edge of muscular IV septum and fused AV cushions. Then it gets closed by the membranous septum
2 things that divide primitive atrium
septum primum and septum secundum
what does septum primum come from
forms in roof of primitive atrium and grows toward AV cushions in AV canal
what does the foramen secundum come from
forms in center of septum primumm, fenestrations that become one big hole
when does the foramen primum start and end
forms between free edges of septum primum and AV cushions, closes when there is fusion with cushions
where does the septum secundum form
the right of septum primum
what is the foramen ovale
opening between the upper and lower limbs of the septum secundum
how does blood get shunted in the embryonic heart
RA to LA via foramen ovale
how is functional closure of foramen ovale achieved
decrease in right atrial pressure (from occlusion of placental circulation) and increase in left atrial pressure (due to pulmonary venous return)
*eventually septum primum and secudum will anatomically fuse
what is the valve of the foramen ovale derived from
septum primum
why is the foramen ovale significant
allows blood to bypass the fetal lungs
path of aorta vs pulmonary artery
aorta: L ventricular outflow
pulmonary artery: R ventricular outflow tract
what are the conotruncal ridges
bulbar and truncal ridges
bulbar and truncal ridges
conotruncal ridges
where do conotruncal ridges form
truncus arteriosis and bulbus cordis
how does the aorticopulmonary septum form
neural crest cells from hindbrain through ph. arches 3,4,6 invade truncal and bulbar ridges - they grow and twist around each other and fuse to form AP septum
what does the AP septum divide
truncus arteriosis and bulbus cordis into the aorta and pulmonary trunk
what does the AP septum meet
the IV septum
which is more ventral between aorta and pulmonary trunk
pulmonary trunk
what are the SL valves called
aortic, pulmonic
how many swellings per valve
3 subendocardial
what area of the heart do the seminlunar valves separate between
aorta and LV and pulmonary artery and RV
what do the AV valves separate
the atrium and ventricles
names and function of AV valves
tricupsid (RA to RV)
mitral (LA to LV)
what do AV valves develop from
proliferation of tissue around endocardial cushions and AV canals
formation of dorsal aorta
initially a pair of tubes that fuse to form a single dorsal aorta which connects with the aortic arch. aortic arch connect to aortic sac in primitive heart tube.
what is each paired aortic arch associated with
a pharyngeal arch
what do the aortic arches connect to
aortic sac
how many aortic arches develop
6, NOT AT THE SAME TIME
where does the arterial pattern develop from 6 pairs of arteries
head and neck
development of arteries in main body
R and L dorsal aortae
what is the ductus arteriosis
a shunt (doesnt shunt everything)
what does the 1st aortic arch become
L and R = maxillary/external carotid artery
what does the 2nd aortic arch become
L and R stapedial artery
what does the 3rd aortic arch become
L and R common carotid/internal artery
what does the 4th aortic arch become
L = part of aortic arch, R = proximal R subclavian artery
what does the 5th aortic arch become
rudimentary aorta
what does the 6th aortic arch become
L= L pulmonary + ductus arteriosus R = R pulmonary aorta
where do the primitive cardiac veins drain
sinus venosus
what are the 3 primitive veins
vitellin (drain yolk sac, low O2)
umbilical (from placenta, high O2)
Common cardinal (from body of embryo, low O2)
what is the fate of the primitive veins
very complex and differs between people
what vein dissapears
R umbilical
what happens to L umbilical vein
umbilical vein within umbilical cord, becomes ductus venosus
what is the superior vena cava a derivative of
R anterior and R common cardinal veins
