Selasa, 31 Juli 2012

Excercise Can Create Oxygen Debt

All the cells in your body need oxygen for respiration and all of this oxygen is supplied by the lungs. The oxygen is carried by the blood to every part of the body.
Sometimes, cells may need a lot of oxygen very quickly. Imagine you are running in a race. The muscle in your legs are using up a lot of energy. To produce this energy, the mitochondria in the muscle will be combining oxygen with glucose as fast as they can, the energy for the muscle.
A lot of oxygen is needed to work as hard as this. You breathe deeper and faster to get more oxygen into your blood. Your heart beats faster to get the oxygen to the leg muscle as quickly as possible. Eventually a limit is reached. The heart and lungs cannot supply oxygen to the muscle any faster. But more energy is still needed for the race. How can that extra energy be found?
Glucose à lactic acid + energy
When you stop running, you will have quite a lot of lactic acid in your muscle and your blood. This lactic acid must be broken down by combining it with oxygen. So, even though you do not need the energy any more, you go on breathing hard. You are taking in extra oxygen to break down the lactic acid.
Were you were running, you built up an oxygen debt. You ‘borrowed’ some extra energy, without ‘paying’ for it with oxygen. Now, as the lactic acid is combined with oxygen, you are paying off the debt. Not until all the lactic acid has been used up, does your breathing rate and rate of heart been return to normal.
Courtesy of:
Jones, Marry and Geoff Jones. 2002. Biology International Edition for IGCSE and 0 Level.     : Cambridge University Press

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