Heart Embryology Flashcards
What layer do the blood islands form in
Splanchnic Mesoderm
How does the primitive heart tube form?
When the blood islands fuse in the midline
Name the 6 sections of the Primitive heart tube from inlet to outlet
Sinus Venosus, Atrium, Ventricle, Bulbus Cordis, Truncus arteriosus, Aortic roots
Where does the RA form from (which sections)
Majority from the primitive atria, some from the sinus venosus
Where does the LA form from?
Some from the primitive atria, mostly from the proximal part of the pulmonary veins
Is the left atria smooth walled or rough walled? Explain why
Smooth. Forms from the proximal part of the pulmonary veins which are smooth walled
State the main differences between the fetal circulation and mature circulation
Fetal- Oxygenation and removal od CO2 in the placenta
Shunts are required to maintain fetal life
What path does the blood take in the fetus, starting at the placenta
Placenta–>Umbilical veins–> Bypasses liver in the ductus venosus–>leads into IVC–>Right atria–>Left atria through the foramen ovale–>Left ventricle–>Aorta
Note from the head and upper limbs blood goes into the SVC–>Right ventricle–>Pulmonary trunk–> Trunus Arteriosus–> aorta
Blood taken back to the placenta for oxygenation by the umbilical artery
Why does the right ventricle need to be used
For development, prevent atrophy
Name the three main shunts and say what they do
Ductus Venosus- By passes the liver
Foramen Ovale- Takes blood from the right atria to the left atria
Ductus Arteriosus- From the pulmonary trunk to the aorta
How many arches are there in the early arterial system
6
What do the fourth and Sixth arches become?
Fourth- To the right, the proximal part of the right subclavian artery
To the left, the arch of the aorta
Sixth- To the right the right pulmonary artery
To the left, thee left pulmonary artery and ductus arteriosus
What is PDA
Persistent communication between the aorta and the pulmonary artery
Ie the ductus arteriosus doesn’t shut
How does the foramen ovale form
1, Endocardial cushion forms (Separates the left and right orifices)
- Primum Septum forms from the roof of atria
- Gap at bottom
- hole opens up called the ostium primum
- Secundum Septum forms
- Ostium Secundum forms lower than the ostium primum
- Gap between the two walls allows blood to pass through
- When child born, pressure in the left atria increases, so higher than in the right
- Pushes walls together, walls fus so holes shut.
- Blood can no longer pass through. Leaves can indentation called the fossa ovali
Causes of Atrial Septum Defect
Septum Primum too short or resorbed, Septum Secundum too small
What is hypoplastic left heart syndrome. Possible causes?
Underdevelopment of the left side of the heart. Reduced blood flow to the left side, so atrophy
How do the left and right ventricles get separated?
Superior and inferior cushions form in the atrioventricular canal.
A muscular portion of the wall grows upwards to the endocardial cushion
Last bit filled in by a membranous bit from the endocardial cushion
How do the great arteries form?
Endocardial cushions appear in the truncus arteriosus. Grow upwards. Form a spiral septum. Separate the truncus arteriosus into the aorta and the pulmonary trunk
What is the transpositon of the great arteries. Consequences?
When the aorta comes off the right ventricle, and the pulmonary trunk comes off the left ventricle
Means deoxygenated blood travels in the aorta–> Cyanosis
What are the four things wrong with the heart in the tetralogy of Fallot
Overriding aorta- The aorta straddles the two ventricles
Large Ventricular septal defect- Hole between the left and right ventricles
Pulmonary stenosis (Narrowing of pulmonary trunk)
Leads to Right ventricular hypertrophy and needs to pump harder to output the same vol of blood
