Biology 0.0 / 5 ? BiologyHealth, illness and diseaseASEdexcel Created by: hannahmurrayCreated on: 20-04-14 18:35 Circulation Move substances around the body 1 of 5 Diffusion Move molecules from high to low concentration by random movement 2 of 5 Open Circulatory System Insects; heart pumps blood into cavities surrounding organs. Heart relaxes> blood drawn back from cavity into heart through valve opening 3 of 5 Closed Circulatory System Vertebrates; blood enclosed in tubes. Creates high blood pressure, blood forced through channels. Travels faster so more efficient 4 of 5 Blood Travel Leaves heart under pressure> along ar 5 of 5
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