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.
Pregnancy Week by Week: One Week Pregnant. During the first week of your pregnancy, you are not actually pregnant. Conception usually occurs about two weeks after your period begins, which means that your period is counted as the first part of your pregnancy, even though you were not pregnant at the time.In other words, week one of your pregnancy begins on the first day of your period.onception usually occurs about two weeks after your period begins, which means that your period is counted as the first part of your pregnancy, even though you were not pregnant at the time. In other words, week one of your pregnancy begins on the first day of your period.