2.  Breathing  Oxygen  Nutrients  Imports  Beating  Blood

3.  organ  in all animals  a myogenic muscular  circulatory system  250 to 300 grams in females  300 to 350 grams in males

4.  it helps to breath  pumps oxygen  over the body  rhythmic contractions

5.  circulation blood  oxygen poor blood  comes into heart right side  oxygen blood  comes into heart left side

6.  2 atrium  2 ventricle  aorta  veins

8.  http://et.wikipedia.org/wiki/S%C3%BCda http://et.wikipedia.org/wiki/S%C3%BCda  http://en.wikipedia.org/wiki/Heart http://en.wikipedia.org/wiki/Heart