Melissa Hand, of Milton Primary School, asks :-

Why do we get butterflies in our stomach when we are about to go on stage?

Chris Lynch, a Neurology Research Fellow at the Otago School of Medicine, responded

Prior to going on stage the automatic nerves that control the heart beat, breathing, sweating, and gut (stomach, intestines and bowel) become very active, and the level of stress hormones in the blood rise. These disturbances may also occur with frightening experiences, pain or anxiety.

As a result of the nerve activity and stress hormones, the heart beat, breathing, sweating and tummy function may be very active. This may be experienced in a number of ways: eg our heart may beat faster, our breathing rate may increase or we feel short of breath, and occasionally our tummy becomes overactive (diarrhoea, vomiting, cramps). The rapid muscle activity that produces many of these symptoms is usually coordinated but occasionally uncoordinated. The muscles responsible for most of this activity are situated about the upper tummy area (eg stomach diaphragm heart).

It is not clear which of the overactive muscles or the rise in stress hormones, or whether there is another explanation for the fluttering felt in the tummy, but the nature of the sensation suggests it is most likely to be overactivity of the heart.