Lecture 19: Heart embryology Flashcards
How does the heart tube develop?
from the fusion of the paired heart tubes that arise from the angioblastic cords
path of blood flow through single tube heart, from cranial to caudal
sinus venosus–>sinoatrial valve –> primitive atrium,–>atrioventricular canal –> primitive ventricle, –>bulbus cordis, –>truncus arteriosis, –> aortic sac,
What is cardiogenic mesoderm
Mesoderm that migrated cranial to the pre-chordal plate during formation of the primitive groove
position of angioblastic cords
directly adjacent to the intra-embryonic coelem
fate of angioblastic cords
eventually form paired heart tubes/aorta, which fuse to form single dorsal aorta and single tube heart
initial position of cardiogenic mesoderm
Cranial to pre-chordal plate, near septum transversum and head of horseshoe part of intra-embryonic coelem. During cranial caudal folding migrates towards the chest, along with those associated structures.
fate of blood islands
form network of arteries and veins within the yolk sac connected to rest of circulation through the vitelline arteries and veins
umbilical artery and vein
connect the chrionic sac/maternal circulation to dorsal aorta (umbilical artery) and sinus venosus (umbilical vein)
What does the fetal circulation lack, notably
circulation through the lungs
What causes the heart to fold
- more dominent proliferation on one side 2. aided by cranial caudal folding
function of fusing AV endocardial cushions
Creates a left and right side of the heart/ left and right AV canals, separates atria from ventricles, fused endocardial cushion plays a role in the formation of mitral valve and tricuspid valve
What forms during heart folding
fused endocardial cushion, primordial IV septum, septum primus
How does Interventricular (IV) septum form
myocardium grows from the the bottom wall between the two ventricles towards the indocardial cushion, while a membranous septum grows down from the endocardial cushion and joins the muscular outgrowth.
ventriculoseptal defect
the most common cardiac defect, found in the membranous septum tissue between ventricles. Most of the time will close naturally
functions of papillary muscle
holds AV valves down, stop them from pro-lapsing (folding back into the atrias) when the ventricles contract.
septum primums
grows down from wall of atrium, towards endocardial tissue. Eventually meets endocardial tissue. Has foramen secundum permanently in it. After formation of foramen secundum top part of septum primum degenerates
foramen primum
hole that forms between the septum primum and endocardial cushion to allow blood to flow from right atrium to left atrium, just by virtue of the septum primum not reaching all the way down to the cushion. will eventually close during development/growth of septum
foramen secundum
Formed from little perforations in the septum primum that coalesce to form a hole further up in the septum from the foramen primum. this one remains open. After formation top part of foramen primum degenerates