Tanno and Iguda have been shrunk down in their minisub called the Microwidget. They’re using it to travel inside the body of their friend Professor Wendy and find out why she’s feeling ill.

The Microwidget is small enough that they could be swallowed like a pill, with a sip of water.

Food and drink enter the digestive system in the mouth, so it makes sense for Tanno and Iguda to enter Professor Wendy’s body in the same way. Food needs to be broken down into smaller pieces before it is digested, and this done by the teeth.

The mouth also produces a liquid called saliva, which is released by the salivary glands, to soften the food and make it easier to swallow. Saliva also contains enzymes that begin to break down the food into the chemicals that the body needs. The tongue pushes the food around the mouth and to the back of the throat where it is swallowed.

Parts of the mouth: this diagram shows what Tanno and Iguda might have seen as they entered the body.

Image credit: staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine1 (2). DOI:10.15347/wjm/2014.010. ISSN2002-4436 used under CC BY 3.0 licence

The average human tongue is approximately 8 cm long and contains between 2,000 and 4,000 taste buds. These only detect 5 different tastes, sweet, sour, salty, bitter and umami (which is a savoury taste). The reason our meals taste different is that they contain different amounts of these taste chemicals.

The tonsils are small organs in the back of the throat. They play an important role in the health of the body by trapping bacteria and viruses. Sometimes they can become swollen and sore and this is called tonsillitis.

Just like fingerprints, teeth are also unique to each person.

Tooth enamel is the hardest substance in the human body, even stronger than bone!

Can you see the different types of teeth in this X-ray of the mouth?

Incisors, canines, molars, premolars?

Our teeth begin to develop before we are are born, but in most cases they don’t come through until we are between 6 and 12 months old. Most children have a full set of 20 milk or baby teeth by the time they’re 3 years old. When they reach 5 or 6, these teeth start to fall out, and are replaced by adult teeth.

There are 3 different types of teeth, each specialised for a slightly different job:

  • Incisors are sharp teeth at the front of the mouth designed to cut food up.
  • Canines are designed to rip and tear food into smaller pieces.
  • Molars and premolars are the back teeth which grind food down into smaller pieces.

Where could Tanno and Iguda end up in Wendy’s body??

Move the slider to see the skeleton and the organs.

Image Credits: Eli Allison, SOMSO® model from Adam,Rouilly

Activity 1

Investigating action of saliva Do this experiment right after lunch, when you’ll have a lot of enzymes in your saliva.

  • 1  Take half a slice of bread and chew it over and over again. Even if the bread tastes disgusting, you should still keep chewing, but don’t swallow! (This activity also works with gluten free bread).
brown tabby cat with slice of loaf bread on head
Photo by Anna Shvets on
  • 2  Notice how the flavour of the bread changes.
  • 3 Once you think you have the answer, you can swallow the bready mush or spit it out (be careful).
  • 4 The bread contains a food chemical called starch. The enzymes in saliva break this down into sugars. Does the change in flavour of the bread now make sense?

Activity 2

Investigating tooth decay Eggshells and tooth enamel both contain calcium carbonate, which can dissolve in acidic conditions. This investigation looks at the effects of a variety of foodstuffs on the calcium carbonate in the eggshells. How might they affect our teeth?

olive and eggs on table
Photo by Ron Lach on
  1. Place a range of liquids into separate glasses, or empty (and cleaned) jam jars. These could include vinegar, milk, water, cola, diet cola, fruit juice, coffee, tea. You choose!
  2. Into each liquid place an egg, or a large piece of eggshell.
  3. Every day, observe what has happened to the eggshell in each liquid. You could take a photo as a record.
  4. Leave for one week. Record which liquids appeared to have dissolved the calcium carbonate. Did some dissolve more than others?
  5. Were some eggshells stained? Can you design an experiment to investigate whether toothpaste might remove or reduce the staining?