Pumped straight from the heart into the body cavity, haemocoel.
Comes into direct contact with the tissues and cells.
Returs through an open-ended vessel.
Transport medium usually carries food and nitrogenous waste, gaseous exchange occurs in the tracheal system.
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Single Closed Circulatory System
Blood travells once through the heart.
Passes through two sets of capillaries.
Blood system is low after passing through both so returns slowly, not efficient.
Fish can be active with a single closed due to their countercurrent gaseous exchange mechanisms. Their body weight and temperature regulation is sorted out due to the properties of water reducing metabolic demands.
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Double Closed Circulatory System
Blood is pumped from the heart to the lungs picking up oxygen and unloading carbon dioxide, and then returns to the heart.
Blood flows through the heart and is pumped out to travel all around the body before returning to the heart again.
Only passes through one capillary network each time so a relatively high pressure and fast flow of blood can be maintained.
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