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UKCD ANA534 Heart De
learning objective answers to heart development
Question | Answer |
---|---|
What do blood islands form? | Blood cells (center of mass), endothelium (peripheral cells of mass), serum/plasma (secreted by center cells of mass). |
After hematopoiesis in blood island ceases in the embryo, where does it occur? | In liver, bone marrow, spleen and thymus. |
What region do the vitelline vessels supply? | The yolk sac. |
Where does the endocardial tube come from? | Lateral plate mesoderm. |
What 3 layers form from this precardiac mesoderm – in order from outside in? | Epicardium, myocardium, endocardium. |
Which of the three layers is the endothelium of the heart? | Endocardium. |
As the heart (endocardial) tube invaginates the pericardial sac into the pericardium, there are 5 dilations from the arterial end to the venous end. List them in order from arterial to venous. | Truncus arteriosus, bulbis cordis, primitive ventricle, primitive atrium, sinus venosus. |
What does each of these Truncus arteriosus form? | aorta and pulmonary trunk |
What does the Bulbis cordis form? | smooth part of the right and left ventricles |
What does the Primitive ventricle form? | trabeculated portions of the right and left ventricles |
What does the Primitive atrium form? | auricles and part of the right atrium with pectinate mm |
What does the Sinus venosus form? | smooth part of the right atrium, coronary sinus and oblique vein. |
Why does the heart tube fold? | The lower regions grow faster than the upper regions and both ends are anchored by the pericardiac sac so its growth causes folding within the sac. |
What do the endocardial cushions become? | The cushions fuse to form the septum intermedium which divides the atrio-ventricular canal into right and left halves. |
What does the septum intermedium fuse with? | The septum primum growing down from above. |
What foramen forms in the fused septa? What does it allow? | The septum secundum. Allows oxygenated blood from maternal placenta to bypass the lungs by flowing from the right atrium into the left atrium. |
What structure allows the foramen ovale to close after birth? | The septum secundum closes the foramen ovale with the pressure differential in atria after birth. |
What forms the limbus of the fossa ovalis seen in postnatal hearts? | The lower edge of the septum secundum becomes the limbus of the fossa ovalis. |
How does the muscular portion of the interventricular septum form? | Grows up from the floor of the primitive ventricle toward the fused atrioventricular cushions. |
Where is the interventricular foramen? | As an upward growth of muscle from the primitive ventricular wall. |
What closes the interventricular foramen? | The membranous interventricular septum formed by the right and left bulbar ridges and AV cushions closes the interventriclar foramen. |
List 3 structures that cease to exist after birth that are associated with the heart and the circulatory system. What does each become? | The ductus arteriosus closes - become the ligamentum arteriosum; The foramen ovale closes - becomes the fossa ovalis; The umbilical vein and ductus venosus close becoming the ligamentum teres (hepatis) and the ligamentum venosum respectively. |