digestion

• What are the specialized regions of the gut responsible for?

  Performing different digestive functions
• Why do different regions of the gut have different glands and secretions?

  To maintain optimal conditions for digestive enzymes
• What begins mechanical digestion in the mouth?

  Chewing food with teeth
• What is the role of saliva in the mouth?

  Moistens food and contains digestive enzymes
• How many pairs of major salivary glands are there?

  Three pairs
• What stimulates the major salivary glands to secrete saliva?


  Sight, smell, taste, or thought of food
• What enzyme is found in saliva?

  Salivary amylase
• What does salivary amylase do?

  Breaks down starch into maltose
• What is the ball of food formed in the mouth called?

  Bolus
• What prevents food from entering the trachea during swallowing?

  The epiglottis
• What is the process called that pushes the bolus down the oesophagus?

  Peristalsis
• What is the structure of the stomach?

  A wide sack-like structure
• What controls the entry of food into the stomach?

  A sphincter muscle
• What is the pH of the stomach contents?

  2.0
• What is the function of hydrochloric acid in gastric juice?

  Provides optimum pH for stomach enzymes
• What type of enzymes are found in gastric juice?

  Peptidase enzymes
• What do peptidase enzymes do?

  Hydrolyse protein to polypeptides
• How long does food remain in the stomach?

  Up to four hours
• What protects the stomach wall from acid and enzymes?

  Mucus lining
• What are the specialized cells in the gastric gland and their functions?

  • Goblet (mucous) cells: Produce mucus
  • Oxyntic cells: Produce hydrochloric acid
  • Chief (peptic) cells: Produce pepsinogen
• What are the two regions of the small intestine?

  Duodenum and ileum
• What allows small amounts of food into the duodenum?

  Relaxation of the sphincter muscle
• How long is the duodenum?

  20 cm
• What is the function of bile?

  Emulsifies lipids and neutralizes acidity
• Where is bile produced and stored?

  Produced in the liver, stored in the gall bladder
• What does pancreatic juice contain?

  Different digestive enzymes
• What enzyme in pancreatic juice hydrolyzes proteins?

  Endopeptidase
• What does maltase do?

  Hydrolyses maltose into glucose molecules
• What are the end products of carbohydrate digestion?

  Monosaccharides
• How are dipeptides digested?

  Intracellularly into simple amino acids
• What adaptations does the ileum have for absorption?

  • Long length increases surface area
  • Folds with villi increase surface area
  • Microvilli on epithelial cells enhance absorption
• What is the function of the lacteal in the villus?

  Transport fatty acids and glycerol
• How do glucose and amino acids enter the bloodstream?

  By diffusion into capillaries
• What is the length of the large intestine?

  1.5 metres
• What is absorbed from the colon?

  Water, mineral salts, and vitamins
• What vitamins are produced by bacteria in the colon?

  Vitamin K and folic acid
• What is the semi-solid condition of indigestible food in the rectum called?

  Feces
• What is the process of egesting waste from the colon?

  Defecation
• What are the uses of the products of digestion?

  • Glucose: Energy release in respiration
  • Amino acids: Protein synthesis
  • Lipids: Cell membranes and hormones
• What happens to excess glucose in the body?

  Stored as fat