|Mouth and Teeth|
|Czech Title||Ústa a zuby|
|Original (French) Title||La Bouche et Les Dents|
|The Skin||The Digestion|
The episode begins with Peter and his sister coming back from a bicycle ride. After leaving their bicycles aside the garage door, they immediately sit for a meal. However, the Mum stops them, seeing that their hands are dirty and prompts the two to go and wash them before eating.
Zooming in on Peter's hands, a few Bacteria are looking forward to entering boy's organism to have a proper meal of nutrients instead of feeding on bicycle grease. However, their plans are foiled when they are washed away by the water from sink. After washing their hands, Peter and his sister go back to eat.
The meal consists of sandwiches and milk glasses. Peter takes his and the narrator introduces the function of oral cavity in digestion:
"The mouth; first stage in the process of digestion. The teeth are specialized tools. The incisors cut, the canines shred, and the molars grind. While the tongue helps to mash the food, the salivary glands provide digestive juices, which also disinfect the mouth and help to keep it free of bacteria. The mouth produces 2 liters of saliva per day."Peter's Sister exclaims that the food feels good on her tongue and slides it out. The narrator introduces the sense of taste:
"The tongue is sensitive to four basic elements of taste: bitter, acidic, sweet, and salty."The scene zooms in on one of the gustatory papillae where the salt taste chiefs observe the process of a Salt Molecule preparing for the taste test. Two Enzymes take a sample of Sodium Chloride contained in the molecule's shaker and put it through a few reactions in a lab. They give the solute to the main Chief who tastes the solution and declares that the food is short on salt and sends the signal.
In the outside world, Peter takes the salt shaker. When the Chief tries the solution this time, he declares that it's too salty and gives the information to the Neurotransmitter. On its way to the brain, he meets with the Neurotransmitters from other taste regions, and all of them argue about who is to be in the lead. Then they realize that the brain receives the concept of taste when messages from four main regions are combined, slow down and walk in sync. In the meantime, Peter takes the pepper shaker and Maestro feels pepper, sneezing out of his nap. The Neurotransmitters reach the nucleus and pass their messages.
Mum arrives and gives the dessert and gives a short lesson about the properties of human teeth, introducing Peter and his sister to the enamel that gives the teeth the incredible strength. As they laugh, the scene zooms in on Peter's Sister's molars, revealing a potential danger.
A group of Streptococcus mutans tries to feed on nutrients in despair at the foot of the tooth, resting on the gums. They feel that only sugar will give them strength and desperately beg for it. In the outside world, Peter's Sister takes a slice of cake, receiving a lot of sugar at the moment. A Bacterium from the group finds the sugar molecule and eats some of its content, quickly building up to his musculature. Soon, the rest of the group and far more Streptococci feed on sugar, becoming stronger than before and make their way up to the crown of the tooth.
Once on the top, the Bacteria try to break the enamel with their pickaxes to no avail. The Chief has an idea to let one of them use the drill, but its effects are proven futile to the very strong material. In the meantime, Peter's Mum asks his son and daughter to brush their teeth now, considering that the teeth might become decayed if they are left unattended after a meal. They go to the bathroom and begin brushing their teeth.
While still trying to drill, the Bacteria hear a loud noise and notice the toothbrush, trying to hide in the bulges of the enamel. Soon enough, the toothpaste splashes in and causes a flood for poor Bacteria, who are washed off back to the foot of the tooth. Streptococci are desperate yet again. One of them, unable to light a match, throws the box right into the puddle of water next to the, now-less-muscular-again Chief, splashing him. He, mad, tries to convince them not to lose hope as Peter's Sister will eventually eat sugary food again.
While playing with Roly Poly, Peter and his sister eat two bonbons, which gives another supply of sugar. The Bacteria quickly organize again and make their way to the top. They are still unable to dig through the enamel with pickaxes, but then the Chief has an idea.
Chief gathers the Bacteria as they look at the plan being carried out. A Bacterium is trying to drill through, then the Chief gives him sugar to eat while he drills. Suddenly, the plan turns out to be a success since the drill broke through the enamel, beginning a dental caries. Peter's Sister feels slight sour feeling in her mouth.
After a few weeks, Peter's Sister is playing with Roly Poly while Bacteria are practically digging deeper in her infected molar. To make matters worse, she supplies them with sugar by eating a slice of bread with sour cream. After one single bite, this is the point where she begins to feel pain and alarms the Mum.