THE DIGESTIVE SYSTEM NATURE’S FOOD PROCESSOR

Before the food you eat can do its job, it has to be absorbed by all the minute cells in your body. First it has to be broken down so that it will dissolve. This process is called digestion and it takes place as the food travels through your digestive tract. The dissolved food then passes into your blood stream and is carried to all the different parts of your body. The foods you eat, which include solids and liquids, go through a giant food processor called your digestive system. This system contains a group of body parts that break down your food both mechanically and chemically. This breaking down of food changes food into nutrients, or microscopic building blocks that can be used by the cells for growth, repair and energy.

One important nutrient is glucose, which the body manufactures from the digestion of carbohydrates. The energy in glucose is changed to a form that can be used by the body. As food travels through your digestive system, it must be broken into nutrient particles small enough to be absorbed into your bloodstream for delivery to every cell in your body. In an adult, food travels through about 9 metres of tubing, a distance about as long as two cars. The large intestine is about 183cm (6ft) in length.

The digestive system can be looked upon as a factory where food is tasted by the tongue, then crushed by the teeth, moistened with saliva and finally, – after elaborate precautions to avoid shunting mistakes – is pushed through the gullet into the stomach, a chemical plant where the most astonishing changes occur. Here millions of cells, too small to be seen, produce a dozen highly complex chemicals which break up the food we have eaten, whether it be meat, spinach, or rice, or cheese, into simpler substances which can be absorbed by the cells of our body and built up into our flesh and bone.

The chemical changes that take place are truly marvellous – well beyond the capacity of the best equipped of our laboratories. And there are five million of these little chemical units in the stomach, some forty million in the intestines, and more than three and a half billion in the liver. They produce, not only the chemicals needed to digest our food, where and when required, but also effective remedies against diseases like cholera and dysentery. At the same time the liver manufactures substances which help the body to burn some of the food we have eaten to provide the heat and energy every living being needs.

The hydrochloric acid in the digestive system is so strong that it could eat through a car body. The stomach’s digestive acids are strong enough to dissolve zinc. But the cells in the stomach lining are renewed so quickly – 500 000 cells are replaced every minute and the entire lining every three days –

that the acids do not have time to dissolve the lining. The digestive system is not only a chemical factory, but a power house as well.