Final Embryo - Heart Development Flashcards
This is when splanchnic mesoderm cells cluster together to form a solid horseshoe-shaped cord of endothelial cells
vasculogenesis
Where does the horseshoe shaped endothelial cord form
within cardiac mesoderm
True or False
The cardiac system is the last system that becomes functioning in an embryo
False; it is the first functioning system
When does the horseshoe shaped endothelial cord hollow out
in the 4th week
How does the horseshoe shaped endothelial cord form a single heart tube
via the folding of the lateral sides of the endothelial tube in ventrally and medially approaching each other at the midline to fuse
Upon lateral folding to form the heart tube, what else fuses
paired dorsal aortae
This repositions the developing heart and pericardial cavity
head folding
prior to head folding, the heart is located where
rostral to oropharyngeal membrane
ventral to pericardial cavity
post head folding, the heart is located where
caudal to oropharyngeal membrane
dorsal to pericardial cavity
ventral to foregut
rostral to spetum transversum (diaphragm)
This acts like a “hinge” in head folding to reposition the heart
oropharyngeal membrane
As the dorsal mesocardium degenerates (day 22), what forms
transverse pericardial sinus
space behind the aorta and pulmonary trunk
What are the layers of the primitive heart tube from deep to superficial
endothelium cardiac jelly myocardium epicardium pericardial cavity parietal pericardium
All of the layers of the primitive heart tube are derived from what
splanchnic mesoderm
At what day does the heart begin to beat
Day 22 or 23
What are the dilations of the primordial heart tube
sinus venosus primordial atrium primordial ventricle conus cordis truncus arteriosus
The sinus venous forms what structures in adults
coronary sinus
sinus venarum
The primordial atrium forms what structures in adults
right and left auricles
portions of the atria
The primordial ventricle forms what structure in adults
left ventricle
The conus cordis forms what structures in adults
outflow tract of the ventricles
caudal (proximal) portion of forms right ventricle
The truncus arterioles forms what structures in adults
pulmonary trunk
aorta
What to primitive structures form the bulbs cordis
truncus arteriosus
conus cordis
This is between the primordial atrium and primordial ventricle
atrioventricular sulcus
atrioventricular canal
This is between the primordial ventricle and conus cordis
bulboventricular sulcus
primary interventricular foramen
Where does the blood flow after the bulbs cordis
aortic sac then pharyngeal arch arteries
When does the formation of the cardiac loop/heart folding takes place when
Days 22-28
As the heart fold, which direction does it move
its cranial end will shift ventrally, caudally and to the right
its caudal end will shift dorsally and superiorly
What is the blood circulation through the primordial heart
sinus venosus primordial atrium atrioventricular canal left (primordial) ventricle interventricular foramen right ventricle conus cordis truncus arteriosus aortic sac pharyngeal aa. dorsal aortae
Partioning of he primordial heart takes place when
Days 27-37
In partitioning the atrioventricular canal endothelial cells near the AV junction do what
revert to mesenchymal state, invade the underlying cardiac jelly, and proliferate
What does the endothelial cells near the AV junction cause
it cause the endocardium to bulge out into the AV canal from its dorsal and ventral walls
The dorsal and ventral endocardial walls develop and fuse together forming what
atrioventricular septum that divide the atrioventricular canal into right and left AV canals
Is the portioned AV canal completely sealed off?
No
Partioning of the primordial atrium involved what
forming two septa that will fuse together to from the interatrial septum
What are the two septa of the intertribal septum
septum primum (first) septum secundum (second)
This develops from the roof of the primordial atrium as the thin, moon-shaped membrane
septum primum
This grows inferiorly to fuse with the endocardial cushions
spetum primun
The opening between the inferior edge of the septum primun and the endocardial cushions is what
foramen primun
As the septum primum fuses with the endocardial cushions and the foramen primum closes, what forms
holes in the center of the septum primun via apoptosis
forming foramen secundum
As the foramen secundum is formed, what beings to develop to the right
septum secundum
The septam secundum grows inferiorly and develops an opening called what
foramen ovale (oval foramen)
Where does blood flow via the foramen ovale and foramen secundum
blood now passed from right to left atrium
After birth, what happens to the foramen ovale
it closes off and there is no blood flow between atria
What forms the valve of the foramen ovale
the septum primum; the cranial portion degenerates
After birth, what happens to the valve of the foramen ovale
The blood pressure of the left atrium exceeds the right atrium which pushed the valve closed and they fuse which closes of the foramen
What does the closing of the foramen oval create
fossa ovalis; a depression in the wall of the right atrium
The muscular portion of the IV septum grows where
cranially toward the AV septum, but does not fuse with it
The opening between the right and left ventricles is what
the interventricular foramen
The membranous portion of the IV septum is derived from what
the mesenchyme of the endocardial cushion tissue
This develops at different orientations through the length of the conus cordis and truncus arteriosus
endocardial cushions
The endocardial cushions of the bulbus cordis fuse with each other forming what
a twisting aorticopulmonary septum that divides the outflow tract into pulmonary trunk and aorta
What is the most common congenital heart defect
ventricular septal defect
What is a ventricular septal defect
failure of IV septum to completely form
What is the anatomical basis for a ventricular septal defect
in most cases (80%) the membranous portion of the septum fails to form, but can also be the muscular portion
What are some of the main transpositions of great vessels
the aorticopulmonary septum grows straight instead of spiraling
aorta arises from right ventricle
pulmonary trunk arises from left ventricle
What is the tetralogy of fallot
interventricular septal defect
hypertrophy of right ventricle
overring aorta
pulmonary stenosis
Aorticopulmonary septum divides what
outflow tract unequally, resulting in stenosis of pulmonary trunk and an overriding aorta
What 3 pairs veins drain into the sinus venosus
vitelline (from yolk sac)
umbilical (deoxygenated blood)
common cardinal (body of embryo)
Originally, the sinus venous opens where
directly into the central dorsal wall of the primordial atrium
Blood flow from the heart gradually shifts to the right side due to what
remodeling of the vitelline, umbilical, and anterior cardinal veins
What is the result of the blood flow remodeling to the right
the right horn of the sinus venosus becomes larger than the left
The right horn of the sinus venosus becomes what
smooth walled portion of the right atrium (sinus venarum)
The left horn of the sinus venosus becomes what
the coronary sinus that drains into the right atrium
As the heart grows, the primordial pulmonary veins and portions of its branches are incorporated where
into the dorsal aspect of the heart, forming the smooth-walled portion of the left atrium
The aortic sac becomes what in adults
ascending aorta
