At what stage does the heart begin to beat and circulate blood?

The heart begins to beat and circulate blood during embryonic development. This stage occurs roughly between the 5th to 6th week of gestation, when the embryonic heart starts to form from mesodermal cells and eventually develops into a tubular structure. By this time, the heart has developed enough to initiate contractions and pump blood, which is essential for providing oxygen and nutrients to the rapidly developing embryo.

Conception refers to the very beginning of pregnancy, when the sperm fertilizes the egg, but there is no heart at this stage. Implantation occurs shortly after conception when the fertilized egg attaches to the uterine lining, but the circulatory system of the developing organism has not yet begun to function. Fetal development starts later in the pregnancy, typically recognized from about the 9th week, when the structures are further developed, but by this time, the heart has already started beating during the earlier embryonic stage. Thus, it is during embryonic development that the heart first becomes functional and circulates blood.