How does the digestive system work?
The digestive system starts in your mouth. Your teeth and tongue help to break down the food so you can swallow it. Saliva (spit) has enzymes which also help to break down the food. That is why it is important to chew your food properly, so the enzymes can start to work.
After you have swallowed your food, it travels down the oesophagus (food pipe). Food doesn’t just fall down your oesophagus. It has muscles which contract in waves to push food down to your stomach.
It takes about seven seconds for food to travel down your oesophagus to your stomach. The job of the stomach is to break the food down. It does this by pummelling the food with muscles in the stomach wall. It also produces acid which helps break the food down further.
Food stays in your stomach for about four hours. By this time, is it mostly liquid. It then passes into the small intestine. It is the job of the small intestine to absorb the nutrients from your food and pass it to your blood-stream.
The small intestine is helped by three other organs: the liver, the gallbladder and the pancreas. The gallbladder stores bile from the liver which helps to digest fat. The pancreas produces enzymes that help digest proteins, carbohydrates and fats. Food does not pass through these organs but they help to get the nutrients from the food out of the small intestine and into the blood-stream.
Your liver is one of the largest organs in your body and has over five hundred different functions. One of the most important is its job as a filter. Once the small intestine has absorbed nutrients into the blood stream, the liver filters the blood to make sure that toxins and any other harmful substances cannot pass through it. The liver also produces bile to break down fats.
Once the food has passed through the small intestine, it travels to the large intestine. The large intestine removes most of the water from the food to turn the food back into a solid. Here, any food that has not been digested by the small intestine is absorbed with the help of yeast and bacteria.
Any solid waste in the large intestine is passed through the anus as faeces (poo). When we go to the toilet, we get rid of all the parts of our food that our body didn’t need. The rest of it has been absorbed into our blood-stream so it can be taken to the parts of the body that need it.