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Above is a diagram of an open circulatory system. An open circulatory system is made up of a heart, vessels, and hemolymph. This diagram shows how the hemolymph, fluid present in most invertebrates that is equivalent to blood, is circulated throughout the body of a grasshopper.
Blood is made up of three parts: red cells, white cells and platelets. Red blood cells are responsible for the oxygen delivery from the lungs to the tissue in the body. White blood cells are a part of the immune system. These components circulate in the fluids in the blood vessels, which is pumped by the heart.