Embryology of the CVS - NOT COMPLETE Flashcards
What does the heart begin as?
Bilateral heart primordia
What is the order of heart development?
- Formation of the primitive heart tube
- Heart looping
- Atrial and ventricular septation
- Outflow tract seperation
Which germ layer does the circulatory system originate?
Mesoderm
What part of the mesoderm does the circulatory system arise from?
Lateral plate splanchinic mesoderm
How does the two primitive heart tubes form?
Angiogenic cell islands move toward the midline and coalesce
Why is the heart one of the first functioning organ of the embryo?
Diffusion becomes diffucult as size increases
What areas of the embryo do blood vessels first appear?
- Yolk sac
- Allantois
- Connecting stalk
- Chorion
What tubes canalize to form the heart tubes?
Angioblastic cords
What does the pericardium develop from?
Intra embryonic coelom
What part of the mesoderm do the parietal and serous pericardium form from?
Somatic mesoderm
What layer of the pericardium forms from the splanchnic mesoderm?
The visceral layer
Describe the different layers of the primitive heart tube from arterial (cranial) end to venous (caudal) end
What way does the primitive heart tube loop?
Anti clockwise
Which two parts of the primitive heart tube grow the fastest to form the cardiac loop?
Bulbus Cordis and Ventricle hence the name bulboventricular loop
How does dextrocardia occur?
The heart tube loops to the left side instead of the right and eventuall then faces the right
What is endocardial cushion formation?
Seperates right atrioventricular opening from left atrioventricular opeing
What two cardiac malformations can occur when endocardial cusion formation and septum formation go wrong?
- Atrial septal defect
- Ventricular septal defect
Study the diagram referring to the left and right AV canals
How does the primordial atrium partition into a left and right atria?
Formation of 2 septa and two foramina to eventually result in the fossa ovale
What is the opening between the septum primum and the endocardial cushion called?
Ostium Primum
What is the role of the foramina ovale before birth?
Allows blood to pass from the right to left atrium without entering the pulmonary system as the lungs are not functioning
What is a clinical sign of atrial septal defect?
Blue baby
How does blood not flow back through the septum?
Acts as a valve
What are the four types of ASD?
- Foramen secudnum defect
- Endocardial cushion defect with foramen primum defect
- Sinus venosus defect
- Common atrium
Describe the partitioning of the primordial ventricle
- Muscular ventricular septum forms (opening known as interventricular foramen
- Aorticpulmonary septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum (this closes the interventricular foramen
- Growth of endocardial cushion seperaties atria and contributes to the membranous portion of the interventricular septum
What are the early heart pacemakers?
Primordial atrium then sinus venosus
What does the AV node and bundle of his develop from?
Cells of AV canal and sinus venosus
What can occur from abnormalities of the conducting syndrome?
Sudden infant death syndrome
What does the aortic sac form?
Aortic arches
What does the bulbus codis form?
Right ventricle and part of the outflow tracts
What does the primitive ventricle form?
Left ventricle
What does the primitive atrium form?
Parts of left and right atrium
What does the sinus venosus form?
SVC
Right atrium
What are the multifactorial aetiologies of congenital heart disease?
- Rubella infection in pregnancy
- Maternal alcohol abuse
- Maternal drug treatment and radiation
- Genetic
- Chromosomal
What is transpositiong of great vessels?
When the pulmonary trunk and the aorta join to the wrong ventrivle and the ductus arteriosis remains open
