(i) Mouth: Food is ingested (the taking in of food or liquid into the body), chewed and swallowed. It is softened by chemicals in saliva (spit). When you swallow, food travels down the oesophagus into the stomach. The food that leaves the mouth is called bolus.

(ii) Stomach: The stomach is a bag with a muscular wall. It mashes food into a pulp, helped by chemicals called gastric juices. When empty it is about 0.5L in size, but when it is full after a meal it can stretch to 4L in size. Food that leaves the stomach is called chyme. It passes into the small intestines after about 4 hours of eating.

(iii) Small intestine: It is a 6 meter long tube where chyme is further broken down. Carbohydrates and fat are broken down and absorbed through the intestine walls into the blood.

(iv) Large intestine: Food that can’t be digested passes into the large intestines. It is then pushed towards the anus where it is excreted as feces.