Experiments: Digestive System

Simultaneous Swallowing and Breathing

Get a mouth full of saliva. Now try to swallow and breathe in at the same time.

A person cannot swallow and breathe at the same time. This is because a flap called the epiglottis covers over the windpipe (trachea) when we swallow so that food does not enter the lungs.

Hold Your Tongue

Put a small piece of soft food such as bread onto the middle of your tongue. Hold the tip of your tongue with your fingers. Now swallow the food.

Because your tongue is needed to push the food to the back of your mouth, you will be unable to swallow.

Investigation of Food Additives

Collect or copy labels showing ingredients on various foods. Refer to the table below and library books to find the names of the additives, their functions and any side-effects.

Colours These make the food look more attractive to some people. Many colours are natural, but some are artificial. It is mostly the artificial ones that have E numbers. E 100 - E 180
Preservatives These stop bacteria growing in food and turning it bad. Some such as salt and alcohol have been known for a long time. The newer ones have E numbers. E 200 - E 290
Antioxidants Air by itself can spoil food. Antioxidants stop or slow down the reaction with oxygen that causes food spoilage in food such as butter. E 300 - E 321
Emulsifiers These chemicals stop separation of creamy liquids such as mayonnaise made from oil and water. E 322 - E 494
Sweeteners These sweeten food without using sugar. E 420 - E 421
Modified Starches These thicken liquid food such as soup. E1400 - E1442