Your organs and tissues of your body rely on oxygen to work properly. Oxygen is delivered throughout the body via the circulatory system, which is composed of the arteries, veins and capillaries that carry blood and oxygen where they need to go.
When we take a breath, oxygen is taken into the lungs and exchanged for carbon dioxide in the blood. Newly oxygenated blood leaves the lungs and travels through pulmonary veins to the heart, where it is then pumped out through arteries to the tissues and organs. Once the oxygen has been depleted and replaced with carbon dioxide, deoxygenated blood returns to the heart via the veins and is pumped back to the lungs for the carbon dioxide-oxygen exchange.
In addition to its oxygen transport role, the blood also plays an important role in delivering nutrients and hormones, removing waste, transporting immune cells and regulating body temperature.
The main components of the blood are red blood cells (RBCs), white blood cells (WBCs) and platelets.