The circulatory system consists of such organs as the heart and blood vessels, as well as the fluid moving through them – blood. The heart is a muscular, hollow organ that pushes blood into the blood vessels. So the heart provides blood with speed, and therefore its movement through the vessels. This movement can occur only through the vessels and not flow into the body cavity. In this case, we are talking about a closed circulatory system. If blood flows out into the body cavity as it moves through the blood vessels, this is not a closed circulatory system.
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