Embryology of the Heart
Terms
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- umbilical veins
- PAIRED vessels that deliver nutrient/O2-rich blood from the placenta to the embryo
- vitelline veins
- Drain the yolk sack
- anterior & posterior cardinal veins
- Return venous blood from the anterior and posterior parts of the embryo, respectively.
- sinus venosus
- Posterior chamber of the heart that receives venous blood
- dorsal aorti
- PAIRED vessels that receive blood from the aortic arches and distribute it to the cranial and caudal ends of the embryo
- segmental arteries
- Supply posterior segments of the embryo
- umbilical arteries
- PAIRED vessels that distribute blood back to the placenta for reoxygenation.
- Why is cardiovascular system the first system to develop?
- The embryo is growing so fast that simple diffusion from placenta to embryo is not sufficient to supply O2 and nutrients to its tissues. Circulation develops to meet these requirements.
- What day does the heart appear? What day does it begin to beat?
-
Appears at day 18.
Begins to beat at day 21. - Shape of embryo at day 18?
- Flat disk
- 3 germ layers?
-
1. ectoderm
2. mesoderm
3. endoderm - Which germ layer does heart arise from? What part of that germ layer?
- Splanchnic mesoderm
- Describe the body cavities at day 18.
- They are paired and lie adjacent to the splanchnic mesoderm
- angioblastic cords
- PAIRED longitudinal cords formed by cells within the splanchnic mesoderm; earliest appearance of the heart
- endocardial heart tubes
- Angioblastic cords begin to hollow out to form these structures.