Heart Development Flashcards
Where do heart cells differentiate?
Cardiogenic field
Where are blood islands and myoblasts found?
The sphlanic layer of the lateral plate mesoderm
What unites to form a horse-shoe shaped plexus?
Blood islands and myoblasts
During week 3 folding, what moves down and becomes thoracic cavity?
Neural plate
What part of the horse-shoe plexus forms the cardiogenic field?
Ventral part
What part of the horse-shoe plexus forms the dorsal aortae?
Latter portions
What occurs during lateral folding of the heart cells?
The ends of the horse-shoe plexus come together and fuse, creating a more tube-lie structure
What occurs during cranio-caudal folding of the heart cells?
Heart tube moves inferiorly and then into the cervical region and then into the thoracic cavity
At what stage, does everything develop in paired structures?
Day 22
What makes connections with developing vasculature?
Simple heart tube
What makes connections with developing venous system?
2 aorta (that rub either side of the embryo)
What separates the myocardium and endocardium?
Cardiac jelly (a layer of connective tissue)
What develops in the epicardium?
A proliferation of cells on the dorsal mesocardium near the vitelline veins
What are vitelline veins?
Veins that drain blood from the yolk sac
What are the 3 layers of the 3-layered heart tube?
Endocardium (endothelial lining); myocardium (muscular wall); epicardium (visceral pericardium)
The end of the heart tube connects to what?
Venous system
What is an anchoring of the heart tube to the foregut?
Dorsal mesocardium
What does the dorsal mesocardiun break down into?
Tranverse pericardial sinus
What is the heart initially suspended by?
Myocardium
List the 5 dilatations that become apparent in the heart
- sinus venous; 2. atrium; 3. ventricle; 4. bulbus cordis; 5. truncus arteriosus
What is the direction of blood flow through the primitve heart?
Through the right and left horns of the sinus venous -> atrium -> ventricle -> bulbus cordis -> truncus arteriosus
Describe the adult structures of sinus venosus
Smootb part of right atrium; coronary sinus (derived from right horn so is vein of left atrium); oblique vein of left atrium (derived from left hor)
Describe the adult structures of the primitive atrium
Trabeculated parts of right and left atria; forms left oracle
Describe the adult structures of the primitve ventricle
Trabeculated part of left ventricle
Describe the adult structures of the bulbus cordis
Trabeculated part of proximal right ventricle; distal outflow of both ventricles
Describe the adult structures of the truncus arteriosus
Aorta; pulmonary trunk
In what direction must the atrium move in week 4 (day 23)?
Cranially and ventrally
In what direction should the ventricle move in week 4 (day 23)
Displaced left
In what direction must the bulbus cordis move in week 4 (day 23)?
Inferiorly, ventrally to the right
As the atrium move in week 4, what does it pull with it?
Sinous venosus
What does the single atrium communicate with?
Left ventricle; right ventricle; outflow tracts
Why must the atrioventricular canal move?
So that when the primitive atrium divides, the AV canal can still communicate with both left and right atria
What are the swellings within the AV node?
Endocardial cushions (they fuse together and separate atrium into left and right)
What grows from the roof of the common atrium down towards the endocardial cushions?
Septum primum (day 40)
As the septum primum fuses with the endocardial cushions, what occurs?
The foramen primum decreases in size (day 40)
What occurs at the roof of the atrium?
Apoptosis (day 40)
What does this area of apoptosis create?
New opening that still allows communication between left and right known as the foramen secundum (day 40)
What is the second growth on the right atrium?
Septum secundum (day 40)
How is access to foramen secundum granted?
By pushing blood against the septum primum from the septum secundum
What is the foramen that remains called?
Foramen ovale
Where does oxygenated blood come from?
Placenta
Describe the function of foramen ovale before birth
Septum primum acts as a valve and so opens the foramen ovale when there is high pressue in the right atrium
Describe the function of foramen ovale after birth
As baby takes its first breath, there is a filling of venous plexus so there is high pressure in left atrium which closes septum primum. This then fuses to the foramen ovale creating fossa ovalis
Where is the left atrium derived from?
Pulmonary veins
What are the 2 components of the ventriculr septation?
Muscular part and membranous part
What does the membranous part ensure?
That the pulmonary comes from the right and the aorta comes from the left
What is the spike outgrowth from the bulbus cordis?
Muscular ventricular septum within the trabecular layer
What shape is the outflow tract?
Spiral
How do the outflow tracts become separated?
Outgrowths known as conotruncal swellings grow towards each other and fuse
When is the final spetum formed?
After birth to allow by pass of blood to lungs
What kind of blood is receieved from the right?
Combination of systemic deoxygenated and oxygenated blood from umbilical vein
Where does blood recieved from the right enter?
Right atrium from IVC
Where does blood from the SVC deflect into?
Both left and right ventricles
Where does blood from the right ventricle go to?
Small portion goes to the lungs but the rest goes to the left sided septum via the aorta
Where are the umbilical veins located?
End of the aorta
