 Breathing  Oxygen  Nutrients  Imports  Beating  Blood

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

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

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

 2 atrium  2 ventricle  aorta  veins

 