8.1a The digestive system

• The basic functions of organs in the alimentary canal

  Mouth:food enters here and is chewed up (ingestion occurs)

  Oesophagus: Peristalsis occurs here to move food from the mouth to the stomach

  Stomach: the food is broken down physically and has acids added to it

  Pancreas and liver: not part of the alimentary canal, but make substances to help digestion

  Small intestine: absorbs excess water and moves indigestible food to the rectum

  Rectum: where the faeces is stored

  Anus: faeces are egested here
• Mechanical digestion: involves physically breaking down food substances into smaller particles.

  Chemical digestion: the process where complex molecules like proteins, fats,carbohydrates are broken down into smaller particles.
• What is peristalsis?


  A series of muscle contractions, they occur in your digestive track.
• What does fat, starch and protein break down to?

  Fats: glycerol + fatty acids

  Starch: glucose/sugar

  Protein: amino acids
• Which nutrient can't be digested and why?

  Fibre is not digested by the body, But it helps the food to pass through your digestive system, so it prevents constipation.
• Define what ingestion is.

  Ingestion is the consumption of a substance by an organism.
• Mechanical digestion involves physically breaking down food substances into smaller particles. It occurs in the mouth, oesophagus and the stomach.
• Chemical digestion is the process where complex molecules like proteins, fats and carbs are broken down into smaller pieces. It occurs in the small intestine.