The respiatory system. Not just blood has to travel through out your body, oxygen has to as well. Buts this creates carbon dioxide, which the respiratory system exports from your body.
I believe the best way of separating the mixture of oil and water is by using a "separating funnel"
http://www.gcsescience.com/e-separating-funnel.htm
for more information see link
Explanation:
"Life on earth is classified into three domains: Bacteria, Archaea and Eukarya. The first two consist completely of single-celled microbes."
Water. Water has a pH of 7, which is RIGHT on what you want!
It receives blood from the whole body. Blood from the lungs enters the heart through the pulmonary vein into the left atrium. ... - Has ventricles that has thicker walls thus more muscular than auricles generating higher pressure to pump blood over long distances.