Circulatiory SystemsOpen Circulatory SystemIn an open circulatory system, there aren't distinct blood vessels. Instead, blood and interstitial fluid (together called hemolymph of haemolymph) are pumped into a cavity called the hemocoel.[1] The hemolymph surrounds the organs, alloing the e!change of substances. The hemolymph is dran bac" toard the heart hen it rela!es. This type of circulatory system is often found in insects, molluscs and other invertebrates.[2] Closed circulatory systemsIn a closed circulatory system, the blood is enclosed inside blood vessels. These vessels can vary in si#e and thic"ness considerably.[2] In such a system the blood is pumped through the vessels by the heart. The blood vessels usually end up as capillaries, letting the blood reach all cells and alloing the e!change of substances. There are to types of closed circulatory system, single systems and double systems.This type of circulatory system is found in vertebrates and some select invertebrates, such as s$uids. ComparisonsOn one hand, open circulatory systems do not re$uire as much energy as closed systems in order to distribute blood. On the other hand, as the blood is pumped under lo pressure, it moves at a slo rate. In a closed system, the blood is under a lot morepressure and so reaches its destination $uic"er. % closed system also reduces the ris" of a loss of pressure or contamination.Single Circulatory SystemIn a single circulatory system, there is one circuit for the blood to travel through. The blood is pumped out of the heart, to the gills of the animal, and then is distributed to the rest of the body. The blood ould then return to the heart in order to be pumped around the body again. &ish are the main e!ample of this type of circulatory system. 'ouble Circulatory SystemIn a double circulatory system, there are to circuits for the blood to travel through.[4] The blood is pumped from the heart, to the lungs, and then bac" to the other side of theheart. The no o!ygenated blood is then pumped to the rest of the body beforeagain returning to the heart. In amphibians and reptiles, the heart may not be completely separated in to to pumps. This results in only three heart chambers. In birds and mammals, the heart is completely separated, resulting in a four chambered heart.[4]ComparisonsIn a single circulatory system, the blood does not return to the heart after visiting the gills. This means that blood pressure ends up being loer, sloing the blood flo. In a double system, as the blood returns to the heart after visiting the lungs, the blood is pumped a second time and a higher blood pressure can be achieved. This means that double circulatory systems end up being more efficient at transporting substances.()* http+,,biology.about.com,od,organsystems,a,circulatorysystem.htm(-* http+,,-.gsu.edu,.bioas!,closeopen.html (/* https+,,.boundless.com,biology,circulatory0system,facilitating0e!change0ith0cells0throughout0the0body,single0vs0double0circulatory0systems, (1* http+,,.ideacenter.org,contentmgr,shodetails.php,id,)))/