HEART
- The heart is a muscular organ located in thoracic cavity, behind the sternum
- The heart consists of 4 chambers seperated by septa & valves.
+ more information of the heart from next topics.
Development:
- Begins at the 3ʳᵈ week of embroying development.
- From mesoderm.
- 1 - The heart begins to develop near the head of the embryo in a region of mesoderm called cardiogenic area.
- 2 - The endocardium release VEGF stimulate the lateral plate mesoderm. to form 2 heart tubes, and a little cavites start to develop call pericardial cavities.
- 3 - The 2 heart tubes fuse to form 1 primative tube The 2 pericardial cavities fuse to form 1 cavity.
* The heart tube connected with the cavity by dorsal mesocardium.
- 4. The Primitve tube quickly form 5 regions.
- 1. Truncus Arteriosus - gives rise to Ascending Aorta
- 2. Bulbus Cordis - " " right ventricle.
- 3. Primative atrium - " " anterior portion of both atrium.
- 4. Primative ventricle - " " left ventricle
- 5. Sinus venosus - " " posterior portion of both atria, SA nodes.
↓ looping
- 5. The primative heart tube elongates and it begins to fold within the pericardium, eventually forming an C shape......
- 6. End of the 5ᵗʰ week, the chambers formed valves are formed.