Question: How did the heart form?

Gemma Barron answered on 11 Nov 2015:

Hi @obricknell,

Thank you for your interesting question. This question has quite a complex answer but, I’ll try and put it as simply as I can but, if you have any other questions after I have given my answer, please ask me another question and I will try my best to answer it.

So, when an embryo in the womb is forming, the heart is the first organ that is formed. When a human heart begins to form it looks like a simple tube, however, rapid growth soon causes joining together, bending and twisting of the tube to form what we would call a simple version of the heart between 18 and 30 days of development. The second step is the formation of two chambers whilst the third step is complete separation of the top two chambers (artia) and the bottom chambers (ventricles) just begin to separate. Finally the four-chambered heart structure is formed when the bottom chambers separate completely. If my memory is correct, human foetuses have a regular heartbeat at about 22 days of pregnancy.
I hope that answers your question. Thanks, Gemma