SSM Heart - Aina Aqilah

BM21110064
SSM Assignment
Development of the heart
The heart begins its development from a group of mesodermal cells called the cardiogenic
area during the third week after fertilization.
During day 19 and 20, the sinus venosus develops into part of the right atrium (posterior
wall), coronary sinus, and sinoatrial (SA) node. Then at day 21, the primitive atrium develops
into part of the right atrium (anterior wall), right auricle, part of the left atrium (anterior wall),
and the left auricle. On day 22, the primitive ventricle gives rise to the left ventricle. Day 23 and
24, the bulbus cordis develops into the right ventricle. Finally on day 28, the truncus arteriosus
gives rise to the ascending aorta and pulmonary trunk.
The primitive heart starts to contract on day 23, as the primitive heart tube elongates.
Because the bulbus cordis and primitive ventricle grow more rapidly than other parts of the tube
and because the atrial and venous ends of the tube are confined by the pericardium, the tube
begins to loop and fold. At first, the primitive heart tube assumes a U-shape; later it becomes
S-shaped. As a result of these movements, which are completed by day 28, the primitive atria
and ventricles of the future heart are reoriented to assume their final adult positions. The
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