Lecture 19: Heart embryology Flashcards Preview

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Flashcards in Lecture 19: Heart embryology Deck (46):

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

1. 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


septum secundum

the second septum grows more anterior to the septum down from the ceiling of the atrium towards the endocardial tissue, stops short of the endocardial cushion, over-laps slightly from septum primum extending up from endocardial cushion


Oval foramen

hole that is between the septum primum and septum secundum, which could overlap but are not connected to each other. Between left and right atria.


what makes up the valve of the oval foramen

the septum primum and septum secundum. the opening is in secundum, flap that covers it up is primum (what moves in rxn to blood pressure). these eventually fuse after birth to create inter-atrial septum. some people will still have holes in their heart


Foramen Ovale

blood bypasses the lung, acts as a shunt between the right and left atria


What causes the foramen ovale to close

the left atrial pressure increases, pulmonary vascular resistance decreases (loss of pulmonary fluid after birth)


left vs. right ventricular outflow tracts

left ventricular outflow --> aorta
right ventricular outflow --> pulmonary artery


Where do conotruncal ridges form

two ridges in the truncus arteriosis and the bulbus cordis, one from each opposite sides of the vessel wall, grow towards each other to meet in the middle while also spiralling around each other 180 degrees


What do the conotruncal ridges fuse to form

the aorticopulmonary septum between primordial aorta and pulmonary artery. The aorticopulmonary septum joins with the interventricular septum


how do the pulmonary and aorta position with respect to each other

they twist 180 degrees as they grow towards each other. This causes the mature anatomy of the pulmonary artery from being anterior at the root, then posterior to the arch, and the anterior to the descending aorta.


semilunar valves

found in aorta and pulmonary artery


formation of semilunar valves

created from 3 subendocardial swellings, which were remodeled to form three thin walled cusps


the atrioventricular (AV) valves

The mitral and tricuspid valves


formation of AV valves

develop from proliferation of tissue around endocardial cushion/AV canals


what does the dorsal aorta rise from

a pair of tubes formed from angioblastic cords, a pair of dorsal aorta are formed, there would be two visible in the cross section


What does the dorsal aorta do

Connects to the aortic arches, which arise from the aortic sac


Where do the aortic arches come from?

They come from the arteries associated with the pharyngeal arches. Six aortic arches develop, each one paired to it's own pharyngeal arch. Each arch has left and right side that arises from central aortic sac and ends in either the left or right dorsal aorta.


what does the 3. aortic arches develop into mature structures

r. and l. 3 --> r. and l. common carotid artery


what does 6 aortic arch develop into

the l. 6 aortic arch gives rise to the left pulmonary artery and ductus arteriosus, and the right pulmonary artery comes from the r. 6 aortic arch


what does the 4 aortic arch develop into

l. 4th --> significant part of the aortic arch,
r. 4th --> prox r. subclavian artery


what are the cardiac veins

vitelline veins from yolk sac (low O2) umbilical veins (high O2) common cardinal veins from embryo body (low O2)


where do the cardiac veins dump into

the sinus venosus


Does everyone have the same veinous set-up

no, highly variable vessel connection pattern between individuals


how many umbilical veins are there initially

two, but only the left one persists, right one disappears


how does blood flow from the placenta

oxygenated blood flows from the placenta through the umbilical vein, then through the ductus venosus in the liver to bypass passing through the liver before the oxygenated blood goes to the heart


Tetralogy of fallot four factors

pulmonary stenosis, ventricular septal defect, overriding aorta, right ventricular hypertrophy, caused by unequal partitioning of the truncus arteriosis by the conotruncal ridges


tetralogy of fallot, why pulmonary stenosis?

because of unequal partitioning of the truncus arteriosis


tetralogy of fallot, why ventricular septal defect

the aortic wall did not join up with the interventricular septum


tetralogy of fallot, why right ventricular hypertrophy

the right ventrical needs to pump against a lot of resistance (the stenosis of R. pulmonary artery)