Digestion

• digestion occurs when enzymes break down complex molecules into simpler ones so they can be absorbed into the bloodstream
• food passes through the digestive system by peristalsis which is the contraction of muscles that push food along
• the digestive system is made up of the mouth, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (caecum, colon, rectum) and anus.
• What is the digestive system primarily composed of?

  A tube that goes through the body with associated organs
• What are the three main processes that food undergoes in the digestive system?

  • Digestion: breakdown of food
  • Absorption: transfer of breakdown products into the blood
  • Egestion: removal of undigested food
• What is peristalsis?

  Waves of muscle contractions that move food through the gut
• What is the main purpose of digestion in the digestive system?

  To produce simple molecules that are soluble
• What do carbohydrates break down into during digestion?

  Simple sugars
• What do proteins break down into during digestion?

  Amino acids
• What do lipids break down into during digestion?

  Fatty acids and glycerol
• Where are the products of digestion absorbed into the bloodstream?

  Through the walls of the small intestine
• What are the functions of the different parts of the digestive system?

  • Mouth: begins digestion of starch with amylase
  • Stomach: begins digestion of protein with protease
  • Pancreas: produces enzymes for digestion
  • Small intestine: completes digestion and absorbs nutrients
  • Large intestine: absorbs water and forms faeces
  • Rectum: stores faeces before egestion
  • Anus: egests faeces
• What enzyme begins the digestion of starch in the mouth?

  Amylase
• What enzyme begins the digestion of protein in the stomach?

  Protease
• What does the pancreas produce for digestion?

  Carbohydrate, protein, and lipid enzymes
• What is the role of bile produced by the liver?

  It helps in the digestion of fat
• What is stored in the gall bladder?

  Bile produced in the liver
• What happens in the large intestine?

  Water is absorbed and faeces are formed
• Where are faeces stored before egestion?

  Rectum
• What is the final step in the digestive process?

  Egestion of faeces from the anus
• What are the types of digestive enzymes and their functions?

  • Carbohydrases: break down complex carbohydrates into simple sugars
  • Proteases: break down proteins into amino acids
  • Lipases: convert fats into fatty acids and glycerol
• What is the role of hydrochloric acid in the stomach?

  It helps digest proteins and kill bacteria
• What is the pH level of the stomach environment?

  pH 2
• How do the functions of the small intestine differ from those of the large intestine?

  The small intestine completes digestion and absorbs nutrients, while the large intestine absorbs water and forms faeces
• What would happen if the pancreas did not produce digestive enzymes?

  Digestion of carbohydrates, proteins, and fats would be incomplete
• What are the changes taking place in each part of the digestive system?

  • Mouth: chewing and mixing food, starch to maltose
  • Stomach: protein digestion, hydrochloric acid release
  • Pancreas: enzyme secretion to small intestine
  • Small intestine: completion of digestion and absorption
  • Large intestine: water reabsorption
  • Rectum and anus: egestion of waste