Frequently Asked Questions: Digestive System

Q. What is the daily amount of energy (in kilojoules) needed by 15-year old boys and girls?
A. 15-year old boys require 9000 kilojoules of energy daily, but 15-year old girls only need 7000 kJ.

Q. What are faeces? Why are faeces brown?
A. Faeces are the undigested wastes that we eliminate from the anus when going to the toilet. Faeces are brown because they contain a brown chemical called bilirubin. This chemical is formed when red blood cells break down.

Q. Why doesn't stomach acid 'eat' away the stomach lining?
A. The stomach wall is lined with mucus that protects it. However, ulcers (erosion of the stomach lining) can occur if a person has unhealthy dietary habits such as drinking too many fizzy drinks or alcohol without having food as well.

Q. Who made the first false teeth?
A. It was the Etruscans who worked with gold 3000 years ago.

Q. How does an antacid work?
A. Stomach juices have hydrochloric acid. An antacid is the opposite of an acid (called a base or alkali) to neutralise the stomach acid so a person feels less discomfort.

Q. Why are there sometimes corn kernels in our faeces?
A. Humans do not have the enzyme required to digest cellulose which is the component of much of the plant matter in corn kernels, so it passes out of our bodies without being digested.

Q. Why do pigeons bob their heads?
A. Pigeons have a muscular neck that gives them that bobbing movement. Therefore they are the only birds that can suck water. All other birds must sip water, tilt their beaks and let gravity allow them to swallow.

Q. How many stomachs do cows have?
A. Cows have 4 stomachs to help them digest plant material more efficiently.

Q. Why does the stomach 'rumble' when a person is hungry?
A. The stomach walls contract and squash the gas and liquids in the stomach to give a rumbling sound.

Q. What are the Crypts of Lieberkuhn?
A. They are small pits in the small intestine that produce digestive juices.

Q. How do they pasteurise milk?
A. Pasteurisation is the process of killing most bacteria in milk by heating the milk quickly at about 72 °C for a few minutes and then quickly cooling it to about 10 °C before refrigeration.

Q. Where did the 'duodenum', the first part of the small intestine, get its name?
A. In the 4th century BC, an ancient Greek named Herophilus claimed it was 12 fingers long ('duodenum'='twelve fingers').

Q. Why are we told not to drink the water when we go overseas?
A. 80% of all sickness in developing countries is caused by unsafe water for drinking and sanitation. The World Health Organisation estimates that 25 000 deaths per day is the result of lack of chlorination of water. We are fortunate in Australia to have efficient water purification plants. In many overseas countries, it is recommended to drink only bottled water.