How the Digestive System Works

Digestion is the process that changes the food we eat into nutrients that the body can use. When we’re feeling healthy, we usually don’t even think about how our digestive system works. But when we’re constipated for example, it can be very helpful to understand more about our bodies and have an insight into how our digestive system works, so that we can try and do something about it.

How food moves through the body

Along the digestive system there is a series of muscles. These muscles contract in a co-ordinated, wave-like motion that mixes food with the body’s digestive fluids and pushes the contents forward. This wave-like movement is called peristalsis.

Food is swallowed down through the throat into the stomach. The stomach holds what we eat and drink. Acidic digestive juices are added to help break down what we eat. Having broken down the food, the stomach then gradually empties the contents into the small intestine.

The role of the small intestine is to absorb valuable nutrients from the food into the blood stream. Having come from the stomach, peristalsis pushes the contents along the small intestine with nutrients being absorbed along the way. Eventually, what is left gets pushed into the colon (large intestine), for the last remaining nutrients to be extracted.

The colon’s job is to squeeze the last minerals and excess water from what remains. The colon does not have any digestive juices but uses naturally occurring bacteria to break down the waste. Peristalsis keeps the contents on the move until they reach the rectum and are ready to be expelled by a bowel movement.

A problem occurs when this peristaltic movement doesn’t work properly and the waste is more difficult to eliminate from the body.

What is normal?

This varies greatly from person to person. What is normal for you may not be normal for someone else. Generally bowel movements may be considered normal if:

  • They occur three times a week or more
  • There is no need to strain at the toilet
  • Stools are quite soft