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B3: Exercise and Our Body
The human body needs to react to the increased demand for
energy during exercise.
The energy that is released during respiration is used to enable
muscles to contract.
During exercise a number of changes take place:
The heart rate increases
Rate and depth of breathing increases
The arteries supplying the muscles dilate (widen)
These changes increase the blood flow to the muscles and so
increase the supply of sugar and oxygen and increase the rate of
removal of carbon dioxide.
Glycogen stores in the muscle are converted to glucose and used
during exercise for respiration.
If muscles are subjected to long periods of vigorous activity they
become fatigued, i.e. they stop contracting efficiently.
If insufficient oxygen is reaching the muscles they use anaerobic
respiration to obtain energy.
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Anaerobic respiration is the incomplete breakdown of glucose and
produces lactic acid.
As the breakdown of glucose is incomplete, much less energy is
released than during aerobic respiration.
Anaerobic respiration results in an oxygen debt that has to be
repaid in order to oxidise lactic acid to carbon dioxide and water.…read more