Summary: Digestion

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• 1 The breakdown of food

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• which two major processes in the breakdown of food happen?

  the physical breakdown and the chemical breakdown

• 1.1 The physical breakdown of food

• Which four kind of teeth do you have and what do they do?

  • incisors= chisel-shaped, front of the mouth, are for biting into soft foods like fruit
  • canines= are pointed, used to eat tougher food but human don't eat a lot so use their canines as extra incisors
  • premolars and molars= first premolars, than molars, have raised parts called cusps with grooves between them, form a crushing and grinding surface at the back of the mouth, breaks food into small pieces

• You have two set of teeth how many teeth do they have and and at what age do you get them?

  1th set= 20 teeth called milk teeth, first teeth emerge through the gum at about 6 months the set is complete at the age of 3
  
  2th =, 32 permanent teeth which begins at the age of 6 and is completed at the age of 17

• 2 along the alimentary canal

• 2.1 When your mouth waters

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• How much water do you make up and which things produce the saliva?

  1.5 liters per 24 hours, Saliva is made by three pairs of salivary glands.

• What does mucin and amylase do?

  mucin= coats the food and makes it easier to swallow
  amylase= egins the breakdown of starch molecules in the food into sugar molecules

• 2.2 When you swallow

• What happens with the food when you chewed it?

  When you have chewed your food  it is made into a pellet called the bolus. This is pushed to the back of your mouth by your tongue.

• What is a gullet or oesophagus ?

  This is the tube connection the mouth to the stomach

• How does a oesophagus or gullet look like?

  Look like:
  Outer layer muscle cells are arranged so that they point along the length of the gullet --> form the longitudinal muscle layer
  
  Inner layer the cells are arranged so that they point around the wall of the gullet --> form circular muscle layer

• How does the oesphagus get the bolus down?

  circular muscles squeeze on the food--> don't contract all at the same time --> first region at the top squeezes then the region a little bit lower --> circular cells can't lengthen themselves -->  longitudinal cells need to contract to stretch the circular muscles once again

• What is the wave of the muscular contraction called?

  peristalsis