Blood is the life giving liquid like substance produced by our body to carry the life giving oxygen to all parts of the body. Four main items carried by Blood to all parts of the body through the arteries, and then capillaries are; Oxygen through RBC Red Blood Cells, which also gives it the bright red colour, WBC White Blood Cells- these are the soldiers or protectors from infection, Plasma, the ingredients derived from the food we eat is carried to the body parts, and finally Platelets, which help in coagulation of the blood. After blood has reached the extremities and its oxygen has been exhausted, it collects the CO2 from the body and brings it back to the heart via the veins, the blue looking vessels on the near surface of the body. This de-oxygenated blood is then pumped to lungs where through the Alveoli, CO2 is exchanged for Oxygen from tha air we breathe and thee oxygenated blood is sent back to the heart from where it is again pumped to various parts of the body through the arteries.