all vertebrates ( fish and mammals ) have a closed system
some vertebrates ( insects ) have a open circulatory system - blood isn't enclosed in vessels so flows freely through the body cavity
closed -
heart pumps blood into arteries, branch out into capillaries
oxygen and glucose diffuse from the blood in capillaries into body cells, blood stays in the blood vessels
veins take the blood back to the heart
open -
heart is segmented, contracts in a wave starting from the back pumping blood into a single main artery
artery opens up into body cavity
blood flows around insects organs, making its way back into the heart segments through a series of valves
advantages of closed systems are that they can be more efficient as there is less resistance to flow due to fewer bends and twists in the blood vessel network
disadvantage of closed systems is that it requires a lot of energy to maintain the pressure needed to push the blood round the circulation
the circulatory system supplies insect cells with nutrients, transports things such as hormones around the body.
doesn't supply insect with oxygen this is done by a system of tubes called the tracheal system
