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Questions and Answers
What does the horseshoe-shaped cardiogenic field consist of?
What does the horseshoe-shaped cardiogenic field consist of?
The heart is formed from paired cardiac primordia that merge during lateral folding.
The heart is formed from paired cardiac primordia that merge during lateral folding.
True
What are the three layers of the heart that form during its development?
What are the three layers of the heart that form during its development?
Epicardium, myocardium, endocardium
The _____ region of the heart receives venous drainage.
The _____ region of the heart receives venous drainage.
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Match each term related to heart development with its description:
Match each term related to heart development with its description:
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What happens to the cephalic portion of the heart tube during its formation?
What happens to the cephalic portion of the heart tube during its formation?
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What is the fate of the sinus venosus in heart development?
What is the fate of the sinus venosus in heart development?
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The bulbus cordis only contributes to the left ventricle.
The bulbus cordis only contributes to the left ventricle.
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The condition where the heart lies on the right side of the thorax is called __________.
The condition where the heart lies on the right side of the thorax is called __________.
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Match the following cardiac structures with their roles:
Match the following cardiac structures with their roles:
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Study Notes
Establishment of Cardiogenic Field
- The cardiogenic field is horseshoe-shaped, located in front of the buccopharyngeal membrane and neural plate.
- Composed of cardiac myoblasts and blood islands called angioblastic cords. These develop into blood cells and vessels.
Formation of Single Heart Tube
- The cardiogenic field is situated anterior to the buccopharyngeal membrane and neural plate, within the thoracic region.
- Cephalocaudal folding of the embryo causes the buccopharyngeal membrane to be pulled forward, moving the heart and pericardial cavity to the thorax.
- Lateral folding during embryo development merges the caudal region of the paired cardiac primordia. This results in a continuous tube except for the caudal-most end.
Results of Folding
- The heart ends up located within the thoracic cavity.
- A single, expanded tube forms, lined by an inner endothelial lining and outer myocardial layer.
- The caudal pole receives venous drainage, while the cranial pole pumps blood out.
Formation of Cardiac Loop (Looping)
- The heart tube elongates and bends on day 23.
- The cephalic portion of the tube bends ventrally, caudally, and to the right.
- The caudal (atrial) portion bends dorsally, cranially, and to the left.
- This looping process is complete by day 28.
Formation of Heart Compartments
- As the cardiac loop forms, local expansions become visible:
- Sinus venosus
- Atrium
- Ventricle
- Bulbus cordis (conus cordis)
- Truncus arteriosus
Fate of Sinus Venosus
- The sinus venosus becomes incorporated into the right atrium.
Fate of Bulbus Cordis
- The bulbus cordis elongates and forms three parts:
- Proximal part forms the trabeculated portion of the right ventricle.
- Middle part forms the conus cordis (outflow tract).
- Truncus arteriosus, which develops into the ascending aorta and pulmonary trunk.
Abnormalities of Cardiac Looping
- Dextrocardia: The heart lies in the right side of the thorax.
Formation of Cardiac Septa (Septation)
- Cardiac septa are major structures that form between days 27-37, separating:
- Common atrium
- Atrioventricular canal
- Truncus arteriosus
- Conus cordis
- Ventricle
Formation of Cardiac Septa
- Cells in the heart tube proliferate to form the endocardial cushions.
- Endocardial cushions are located at:
- Atrioventricular junction (between atrium and ventricle)
- Truncoconal junction (between conus cordis and trunk)
Formation of Cardiac Septa
- The endocardial cushion at the atrioventricular junction develops into:
- Interatrial septum
- Atrioventricular canal
- Membranous part of the interventricular septum
- The endocardial cushion at the truncoconal junction develops into:
- Aortic and pulmonary channels
Formation of Interatrial Septum
- Endocardial cushions at the atrioventricular junction proliferate.
- Septum primum (sickle-shaped crest) grows from the roof of the atria.
- The opening between the septum primum and endocardial cushion is called the ostium (foramen) primum.
- The septum primum and endocardial cushion grow to close the ostium (foramen) primum.
- Some cells in the septum primum die, creating a new opening known as the ostium (foramen) secundum.
- These foramina allow free blood flow from right to left due to low left atrial pressure.
- A crescent-shaped fold appears on the right side of the septum primum, called the septum secundum.
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Description
This quiz covers the establishment of the cardiogenic field and the formation of the single heart tube during embryo development. Explore how embryonic folding affects heart positioning and structure. Test your knowledge of cardiovascular embryology processes.
