Week 10 Heart murmur Flashcards
What type of fetal cells form the heart tube?
Mesodermal cells
How does the fetal heart form?
Mesodermal cells form two heart tubes connected by an arch.
The two tubes merge into one heart tube.
The heart tube folds and the internal structure separates into four chambers.
When do the cardiac precursor cells condense to form 2 endocardial tubes?
Day 19
When does the trilaminar embryo fold laterally, fusing the two endocardial tubes into a single heart tube?
Day 21
When does the heart tube begin to loop?
Days 23-28
When does the septum primum begin to grow and the atrioventricular septum begin to form?
Day 28
When does the aorticopulmonary septum begin to form?
Day 35
When is the atrioventricular septum complete?
Day 42
When is the foramen primum complete?
Day 46
When does the aorticopulmonary septum form?
Day 35-56
Which embryonic germ layer do the cardiac precursor cells form in?
Splanchnic mesoderm
What does the ectoderm give rise to?
CNS and neural tissues
Skin epidermis
Skeletal tissues
Teeth
What does the mesoderm give rise to?
Muscle, bones, cartilage
Blood cells and vessels
Skin dermis
Kidneys, ureters, genital system
Cardiac tissue
What does the endoderm give rise to?
GI tract lining
Liver, pancreas (except islets)
Respiratory tract lining
Bladder
What causes the positioning of the heart to bulge further into the future pericardial cavity?
Cephalocaudal folding
Day 19-21
When does the heart begin to beat?
Day 22
Discuss the aortic sac
Superior arms of the heart tube.
Gives rise to:
Ascending aorta
Brachiocephalic artery
Pharyngeal arch arteries
Discuss the bulbus cordis
Below the aortic sac.
Made up of:
Truncus Arteriosus which becomes the aorta and pulmonary trunk
Bulbus Cordis which becomes the right and left ventricle outflow
Discuss the primitive ventricle.
Middle area of the heart tube.
Becomes the right and left ventricles.
Discuss the primitive atrium.
Below the primitive ventricle.
Becomes:
Left auricle and atrium
Right auricle and atrium - rough part
Discuss the sinus venosus.
Bottom portion, including the arms of the heart tube.
Becomes:
Right atrium - smooth part
Coronary sinus
Part of SVC
When does the heart tube begin to loop and when is it complete?
Day 23-28
Discuss the process of heart looping.
Aortic sac: remains fixed during looping
Bulbus cordis: moves inferior, anterior, and to the right.
Primitive ventricle: moves to the left
Primitive atrium: moves posterior and superior
Sinus Venosus: moves posterior and superior
What are the 5 septa of the fetal heart?
- Atrioventricular septum
- Foramen ovale
- Interventricular septum (muscular portion)
- Aorticopulmonary septum
- Interventricular septum (membranous portion)
Endocardial cushions
Swellings/thickenings of migrated cells that will fuse to form septa and valves.
Located on all four sides of the heart, at the level of where the atrioventricular septum will be.
Invaginate to form the beginnings of atrioventricular septums, dividing the heart into atria and ventricles and right and left.
How is the atrioventricular septum formed?
Day 28-42
Dorsal and ventral endocardial cushions grow towards each other and fuse.
Discuss formation of the foramen ovale.
Day 28-46.
Day 28-35 Septum Primum forms from the dorsal part of the roof of the primitive atrium and grows towards the fusing endocardial cushions. Septum primum has holes to allow blood to pass from R to L
Foramen Secundum
Holes at the top of the septum primum that eventually coalesce to form the foramen secundum.
Septum Secundum & Foramen ovale
After the foramen secundum forms in the septum primum, the septum secundum grows down from the ventral part of the roof of the right atrium.
It does not fuse with the endocardial cushions.
This gap is the foramen ovale.
The pressures at birth force the septum secundum against the septum primum and closes the gap of the foramen ovale.
Which septum is movable allowing blood flow between the R and L atria?
The Septum primum is flexible.
The Septum secundum is sturdy, providing structural support.
Discuss the formation of the muscular interventricular septum.
Day 28-46
Grows upward from the floor of the primitive ventricle towards the atrioventricular septum.
Gap at the top is the interventricular foramen, allowing blood flow from R to L ventricle.
Discuss the formation of the aorta and pulmonary trunks.
Ridges form from the bulbus cordis and truncus arteriosus.
These ridges widen and fuse while creating a spiral separation.
One side is the aorta and the other is the pulmonary trunk.
List 5 unique aspects of the fetal circulatory system at term.
- Umbilical vein
- Ductus venosus
- Foramen ovale
- Ductus arteriosus
- Umbilical artery
Discuss the formation of the interventricular septum, membranous portion.
Day 42-56
The aorticopulmonary septum grows downward to the muscular interventricular septum and merges with the atrioventricular outgrowth.