9. Nutrition In Humans


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9. Nutrition In Humans

  1. 1. 9.1 Composition of Food Today’s Learning Objectives:  Name the five main food groups  Name the main types of carbohydrate found in food.  Name the chemical elements present in carbohydrate, protein and fat.  Name the molecular units from which carbohydrates are made up.  Name the molecular units from which proteins are made up.  Name the molecular units from which fats are made up.  State how the units of carbohydrate, protein and fat are joined together.
  2. 2. • The three main food groups are …? Carbohydrates Proteins Fats
  3. 3. Carbohydrates G G G G G G Starch (insoluble) G G GG G G G Maltose (soluble) Glucose (soluble)
  4. 4. Fats and Oils Fatty Acid Fatty Acid Fatty Acid Glycerol Fat Molecule
  5. 5. Proteins Protein (insoluble) Peptides Amino acids (soluble)
  6. 6. nn Food Groups Growth and repair Energy Energy/ stored energy Use Diagram Amino Acids Fatty acids & glycerol Glucose/Maltose molecules Basic Units Carbon Hydrogen Oxygen Nitrogen Carbon Hydrogen Oxygen Carbon Hydrogen Oxygen Elements Present ProteinsFatsCarbohydrates nn
  7. 7. 9.2 Alimentary Canal Today’s Learning Objectives:  Identify the associated organs of the alimentary canal.  Describe the role of the mouth in the mechanical breakdown of food.  Describe the role of saliva in aiding swallowing.  Describe peristalsis in the oesophagus and state its role.  Describe the action of the muscles of the stomach and explain their function.
  8. 8. Mouth Salivary Gland Liver Stomach Large Intestine Small Intestine Anus Rectum Pancreas Gall Bladder Oesophagus Tongue
  9. 9. Peristalsis  Takes place along the whole length of the gut from mouth to anus, to move food through the gut. Layers of muscle Contraction of muscle Relaxation of muscle Direction of movement
  10. 10. 9.3 Digestion Process Today’s Learning Objectives:  State the connection between molecular size and the solubility of food.  Explain the importance of solubility of food molecules.  Define the term digestion in terms of food molecules.  Describe where starch digestion takes place and what happens to the starch molecules after they are digested.  Describe where protein digestion takes place and what happens to the protein molecules after they are digested.  Describe where fat digestion takes place and what happens to the fat molecules after they are digested.  Name the different types of enzyme involved in digestion of starch, protein and fat.
  11. 11. Digestion  Digestion is the breakdown of large, insoluble molecules into small, soluble molecules by digestive juices.  The digested food molecules can then be absorbed through the wall of the small intestine into the blood stream.
  12. 12. Digestive Enzymes  Most digestive juices contain enzymes.  There are groups of enzymes involved in digestion.  Each group acts on a different type of food, called the substrate.  The substrate gets broken down by enzymes to substances called products.
  13. 13. Digestive Enzymes PeptidesProteinPepsinProteases Fatty acid and glycerol FatsLipaseLipases MaltoseStarch Salivary amylase Amylases ProductsSubstrateEnzyme Enzyme Group
  14. 14. 9.4 Stomach and Digestion Today’s Learning Objectives:  Name three substances secreted by cells in the stomach wall and name the structure these cells form in the stomach wall.  State the function of these three substances.  State why pepsin is not produced in its active form.  State the pH of the stomach contents.  Explain why the pH of the stomach needs to be low.  Name the substrate for the enzyme pepsin.  Describe the effect of pH on the activity of pepsin.
  15. 15. Columnar cells secrete mucus to protect stomach lining from digestive enzymes and stomach acid. Inside the stomach…
  16. 16. Gastric glands in the folds of the stomach wall contain cells which secrete: mucus digestive enzymes acid Enzyme producing cells secrete an inactive enzyme which is activated after its release from the gland. Pepsin (the activated enzyme) breaks down proteins into peptides. The enzyme cannot be active when it is secreted or it would break down the cells!!
  17. 17. Acid secreting cells release hydrochloric acid. - creates the conditions to activate pepsin - provides optimum pH for digestion of protein (pH2). Mucus secreting cells produce a slimy mucus to protect stomach wall from damage. All three of these cell types are in the gastric gland.
  18. 18. 9.5 Temperature and Protein Digestion Today’s Learning Objectives:  Explain why egg white suspension has a cloudy appearance.  Explain why egg white suspension clears when acted on by pepsin.  Describe an experiment to show the effect of temperature on the activity of pepsin.  State how experiments can be made more reliable.  State why investigations should always be evaluated.
  19. 19. 9.6 Absorption Process Today’s Learning Objectives:  Define the term ‘absorption’.  Explain the importance of molecular size in the absorption of food from the alimentary canal.  Describe a visking tubing experiment to demonstrate absorption.  Describe the adaptations of the intestine for absorption.  Label a diagram of a villus.  Describe how villi help to increase the surface area and state which vessel absorbs glucose and amino acids and which absorbs the products of fat digestion.
  20. 20. The Small Intestine
  21. 21. Villi are finger like folds in the surface of the small intestine
  22. 22. The Villi Thin epithelium Blood capillary Tiny lymphatic vessel (lacteal) Enzyme secreting gland - Glucose and amino acids, transported in the blood stream. - Fats transported in the lymphatic system.
  23. 23. 9.7 Where it all Goes Today’s Learning Objectives:  Name the organ in the body which regulates the glucose and amino acids in the bloodstream.  Describe the fates of excess glucose molecules and amino acid molecules.  Describe the fates of glucose molecules and amino acid molecules when they are used in the body.  Name the fluid which transports absorbed food molecules from a lacteal.  Describe three possible fates for the products of digested fat molecules in the body.  State what the main contents of the large intestine are. Describe absorption and elimination in the large intestine.
  24. 24. The Liver Hepatocytes, liver cells, process incoming nutrients and produce bile, a fat emulsifier, as well as store vitamins and detoxify the blood.
  25. 25. The liver… - regulates glucose by allowing all that is required to pass into the general bloodstream. - excess glucose stored in the liver as glycogen and released as the body needs it (large glucose excesses are converted to fat and stored elsewhere in the body.) - allows as much amino acids as required to enter blood stream. Excess molecules may be converted to urea and later removed by kidneys. - transports vitamins and minerals in bloodstream, via liver cells. Excess vitamins or minerals are either stored or excreted.
  26. 26. Large Intestine By this point only indigestible material and water remains. The large intestine absorbs water and remaining material is excreted as faeces.
  27. 27. DigestiveSystem