Redistributing of blood during exercise

As we start to exercise our muscles require more energy, therefore we need more food and increased oxygen to produce this. This extra oxygen must be made available to our blood through increased breathing and depth of breathing to obtain this. Our blood cells also need to react to this extra oxygen as they need to deliver more oxygenated blood to the working muscles. When the ATP gets used up within the muscles, then the muslce starts to produce several metabolic byproducts in the biochemical process of energy transfer, ie. carbon dioxide, adenosine. When these byproducts leave the cells within the muscles this then enables the capillaries which have been previously closed to dilate. Along with the dilated arteries, this increased blood flow transports the oxygenated blood required to the working muscle.

There is also a bit of division going on as the blood flow is redistributed less to all other major organs apart from the brain and the heart where more blood flows to the working muscles. This is down to the sympathetic nervous system which stimulates the nerves to the heart and blood vessels. It is this nervous stimulation which cause the arteries and veins to either contract or constrict, so restricting blood flow to the tissues. So as the rest of the body starts to get the message to constrict the blood vessels and the muscles dilate their blood vessels. The blood flow from the say the stomach, kidneys etc is diverted to the working muscles.