6 Questions
What theory does the text discuss regarding embryonic development?
Excess blood in the left atrium causes a bulge
What is one problem identified with the theory discussed in the text?
Speculation in assuming both valves start with three leaflets
What effect does the excess blood in the left atrium have according to the theory in the text?
Forces two leaflets to separate
What role does the ductus arteriosis play in limiting blood return to the atrium?
Aiding in closing off a connection between the pulmonary artery and aorta
How does the high resistance in the lungs impact blood circulation according to the text?
Limits blood flow returning to the atrium via pulmonary veins
Why does the left atrium bulge according to the theory presented in the text?
To accommodate excess blood from the pulmonary veins
Study Notes
Fetal Heart Development
- Blood pressure is higher in the right side of the heart than the left during embryonic development.
- The left atrium receives blood from both the pulmonary veins and the right atrium.
- The excess blood in the left atrium causes it to bulge, making room for the increased blood volume.
Theories on Mitral Valve Development
- One theory proposes that the bulging of the left atrium forces two leaflets of the proliferating cell to join and form one leaflet.
- This theory assumes that both the tricuspid valve and mitral valve start with three leaflets, but this assumption is not supported by facts.
- The theory has limitations, such as the ductus arteriosis and high resistance in the lungs, which reduce the blood returning to the atrium via the pulmonary vein.
Limitations and Unknowns
- The "bulge" argument is weakened by the aforementioned factors.
- The exact mechanism behind the development of the mitral valve is still unknown.
- Fetal development and early fetal circulation are likely to be involved in the answer, but more research is needed.
Test your knowledge on a theory related to embryonic development and the heart, which explains how pressures in the heart chambers affect blood flow. Explore the concept of bulging in the left atrium during development.
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