CV Development Flashcards
Where doe the heart develop early on?
Rostal to the developing nervous system. In cariogenic area near head, from splanchnic mesoderm.
How does the early heart get to the thorax?
Folding of the embryo brings the cariogenic structures into the thorax.
What is any abnormal development of the heart usually caused by?
Neural crest cells
Where do neural crest cells go during the rostral-caudal folding of the embryo?
Neural crest cells (ectoderm cells) from the cervical and thoracic region migrate into the developing cardiac structures and supply visceral sensory and motor (autonomic) innervation to cardiac structures.
What do neural crest cells do to cardiac structures?
Supply visceral sensory and motor (autonomic) innervation
What is the significance of neural crest cell migration?
Pain may be referred from hear to the chest wall, neck and all the way to the angle of the mandible
What fibers supply the neck?
Cervical sensory fibers
What is NOT derived from neural crest ectoderm?
Cardiac muscle cells
What are the three developing venous systems?
- Vitelline veins
- Umbilical veins
- Cardinal veins
What do vitelline veins do?
Form the portal system of veins that drain the GI tract
What do umbilical veins do?
Drain the placenta
What do Cardinal veins do?
Veins related to the caval system (give rise to caval system)
(superior and inferior vena cava)
What vessel is derived from embryonic cardinal veins?
Azygous vein
What is the pathway of blood through the developing heart tube?
- The vitelline, umbilical and cardinal veins drain into the sinus venosus.
- Blood from the sinus then enters the developing atrium –> ventricle –> bulbs cordis –> truncus arteriosus
- Then blood flows into the aortic sac from which the aortic arches take origin
What are the five components of the developing heart tube?
- Sinus venosus
- Primitive atrium
- Primitive ventricle
- Bulbus cordis
- Truncus arteriosus
What are the entry and exit sites for the heart of the developing embryo?
Enter: Sinus venosus
Exit: Truncus arteriosus
Blood returning to the developing heart from the developing gastrointestinal tract enters the:
Sinus venosus
What happens very early in development to the two heart tubes?
The two tubes fuse
What does folding of the early heart tube to the right cause?
It brings the superior and inferior vena cava to the right
-Acquires the general external appearance of the adult heart
What are two developmental anomalies related to folding?
- Dextrocardia
2. Detrocardia with situs inversus
What is Dextrocardia?
Condition in which the heart tube bends to the left instead of to the right.
-Heart is displaced to the right and there is a transposition whereby the heart and its vessels are reversed., as a mirror image.
What is Dextrocardia with situs inversus?
Dextrocardia plus a transposition of the viscera (other internal organs)
When are cardiac defects greater (dex vs. dex w/ situs inverus?
When there is dextrocardia (usually these people don’t survive), but much less problems when there is dectrocardia with situs inversus.
When the developing heart tube bends to the left rather than to the right, the developmental anomaly is referred to as:
Dextrocardia
What are the roles of the endocardial cushions in heart development?
- Divide the atrioventricular canal into right and left channels
- Contribute to the formation of the tricuspid and mitral valves
- Contribute to the membranous portion of the interventricular septum
- Participate in the closure of the primary atrial septum
What is the endocardial cushion made up of?
Extracellular matrix than enlarges and produces outgrowths from the anterior (ventral) and posterior (dorsal) walls of the developing heart tube that serve to separate the primitive atrium from the primitive ventricle.
-And provide right and left channel for flow of blood from primitive atrium to primitive ventricle
What are the developmental anomalies associated with abnormal endocardial cushion development?
- Mitral atresia
- Tricuspid atresia
- Persistent atrioventricular canal (no cushions combine to close this)
- Atrial septal defect (ASD) (patent primary foramen)
- Ventricular septal defect (VSD)
The endocardial cushions contribute o the development of all the following heart structures EXCEPT the:
a. Foramen ovale
b. Interatrial septum
c. Interventricular septum
d. mitral valve
e. tricuspid valve
Foramen ovale
What happens during the division on the primitive atrium?
- Primary septum and secondary septum partition the primitive atrium into right and left atria
- Primary septum forms first
How does the primary septum develop?
- Primary septum begins development from the atrial walls and grows toward the developing endocardial cushions. The opening between the primary septum and the endocardial cushions is the primary foramen.
Where does the secondary septum (of primitive atrium) form?
To the right of the primary septum.
-It also grows toward the endocardial cushions
How does the secondary foramen form?
Before the primary septum fuses with the endocardial cushions, and closes the primary foramen, a breakdown of the primary septum begins to occur which forms the secondary foramen.