Answer:

1.a systemic circulation and a pulmonary circulation.

3.The heart's structure is what enables it to function as such an efficient pump. ... These valves carefully regulate blood flow through the chambers by acting as one-way doors within the heart. The walls of the heart and the valves keep the blood on a "one-way street" through the heart and out to the body and back.

6.Maintain a healthy weight.

Don't smoke.

Exercise a minimum of 30 minutes a day, most days of the week.

Maintain a healthy, low-fat, low-cholesterol diet with more fruits, vegetables, and whole grains.

Avoid trans fats and saturated fats, which are often found in processed foods and fast food.