BIOLOGY BASICS

WHY do our bodies do the things they do? This week: burping

BELCHING is how we expel gas from the stomach. ‘The stomach is a J-shaped sack that is usually three-quarters full of liquid and food being digested,’ says Dr Adam Taylor, a senior lecturer in anatomy at Lancaster University.

‘The rest is air, which allows for the contents to be churned around just as clothes are churned in a washing machine.’

As we eat and drink, he says, air is swallowed, too, and builds up in the stomach, making it swell. The body’s reaction is to let this out by burping.

‘The noise of the belch comes from air rushing back up the throat and hitting surfaces, such as the epiglottis,’ says Dr Taylor. ‘The faster you eat, the more likely you are to burp. Chewing gum, sucking boiled sweets and drinking fizzy drinks increase the amount of air you introduce into your stomach — and, therefore, the volume of burps you produce.’