In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart.
Best Answer: Well they always calculate due date based on your period. Even the doctor will. If you know your exact date of conception you either add 2 weeks to that date or just count 38 weeks from that date.40 weeks gestation is based on your last period. So technically speaking a women is never actually pregnant for her first 2 weeks.est Answer: Well they always calculate due date based on your period. Even the doctor will. If you know your exact date of conception you either add 2 weeks to that date or just count 38 weeks from that date.
  There are handy calculators around the web to figure this out, or you can count back 9 months from your due date (February 8) and add two weeks (February 22) to get a â¦ rough idea of conception.