Blood circulation is very important in the body of all organisms. It is through blood circulation that organisms are able to absorb water and mineral salts in the body. It is therefore healthy having blood flowing all over the body in the veins. The flow of blood around the body takes place in a series of processes that vary from one organism to another (Meng et al. 1201). Some animals have double circulation of blood where blood goes to the heart twice for a complete round while other animals only have single circulation where blood goes through the heart once for a complete circulation. A typical example of the above statement is fish where blood only goes to the heart once for a complete circulation and man on the other hand experiences double circulation.Mammals experience double circulation. In mammals, the right side of the heart is always responsible for receiving blood from all other parts of the body (Meng et al. 1201). This kind of blood is usually low in oxygen, also known as deoxygenated blood and it enters right atrium before it goes down to the right ventricle, which immediately pumps it to the lungs for purification. The purified blood then comes back to the heart through the left atrium down to the left ventricle where it is pumped again to the rest of the body parts (Gutierrez et al. 2367). Contrary to circulation of blood in man, in fish, the circulation of blood is just single round and not double. Fish contains only one ventricle and one atrium in their hearts. The blood less in oxygen that is the deoxygenated blood is from the rest of the body parts gets in the heart through the atrium down to the ventricle where it is pumped out to the gills where purification of the blood takes place (Gutierrez et al. 2369). With fish, purification of blood takes place in the gills not lungs. From the gills, the blood then flows through to all body parts and the circulation is complete.Work CitedGutierrez, Mario, et al. “Presence of Rigid Red Blood Cells in Blood Flow Interferes with the Vascular Wall Adhesion of Leukocytes.” Langmuir 34.6 (2018): 2363-2372.Meng, Lingzhong, et al. “Cardiac Output and Cerebral Blood FlowThe Integrated Regulation of Brain Perfusion in Adult Humans.” Anesthesiology: The Journal of the American Society of Anesthesiologists 123.5 (2015): 1198-1208.