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.
If you are unsure of how to calculate the weeks of pregnancy, just ask for your next appointment how far along you are in weeks and days. An example might be 19 weeks and 2 days. Simply count back two days to figure out what day of the week 19 day 0 was and count up from there weekly. Weeks of Pregnancy. Week 1.