Mouth
Teeth
As a child you have 20 milk teeth, all of which you will lose before turning 13, to make room for the larger teeth which you are to have for the rest of your life. Adults have 28 teeth and, if there is space enough, four more – the wisdom teeth.
Tongue
You may have noticed the small bumps on your tongue. These are your taste buds – pockets of sensory cells – enabling us to experience different tastes - salty, sweet, sour and bitter. There is also a fifth taste called umami which enhances the other flavours, and through evolution has helped us find protein-rich foods. In recent years, researchers have discovered that the taste receptor cells also respond to fatty and creamy foods.
The taste receptor cells make us appreciate food that can be used as building blocks in our bodies, and help us avoid harmful food. Toxins, for example, are often bitter. The taste of sweet is most easily experienced at the tip of the tongue. Far out on both sides of the tongue there are many taste buds that can detect a taste of salty. A taste of sour is best felt on the sides of the tongue, a little farther back, and the taste of bitter is experienced in the far back of the tongue.
The taste buds are not only located on the tongue but also in the throat and the palate.
Saliva
It’s enough to think about good food to make our mouths water. The brain is preparing the body to eat. Our spit – or saliva – is needed to help break down the food and make the texture become soft and smooth. We produce more than 1 litre of saliva each day!
Saliva is generated in the salivary glands – three on each side inside the mouth and under the tongue. The saliva contains various substances that break down the food. One example is the amylase enzyme that divides starch into smaller components so that the body can more easily use it as energy. Did you know that saliva also contains substances that can kill harmful bacteria!
Epiglottis & Uvula
A reflex makes the food you swallow go down the oesophagus while simultaneously closing a lid covering the opening to the trachea. If you look as far back as you can inside your mouth, you will see something called the uvula – a flap that folds backwards and upwards and forms a lid that blocks the pathway to the nasal cavity when you eat and drink. We obviously don’t want food going up into our noses when we eat!
A belch is air that went down into the stomach and that comes back up through the oesophagus and mouth. Hiccups, however, are caused by a cramp in the midriff – the diaphragm – that forms a sound when the epiglottis in the throat closes as you inhale.
Did you know that:
- Enamel, which protects our teeth, is the hardest tissue in the body.
- The salivary glands in the mouth produce 1–1.5 litres of saliva each day. Saliva helps break down food.
- Starch from food is “cut” in the mouth by the enzyme amylase. This enzyme can be found in our saliva.