Nutrition in Mammals
Lesson Objectives: <ul><li>Holozoic nutrition </li></ul><ul><li>Introduction to the human digestive system </li></ul><ul><...
Holozoic nutrition  (feeding on ready made complex organic matter) <ul><li>Digestion : process where large food molecules ...
Study tips: <ul><li>Always try to relate the structure of an organ with its function </li></ul><ul><li>This serves as an e...
Overview of the human digestive system Mouth  ↓ Oesophagus ↓ Stomach ↓ Small Intestines ↓ Large Intestines ↓ Rectum ↓ Anus...
Types of digestion <ul><li>Mechanical digestion </li></ul><ul><li>Break down particles into smaller pieces so as to increa...
Buccal Cavity (Mouth)  <ul><li>Mechanical digestion </li></ul><ul><li>large  small </li></ul><ul><li>Chemical digestion </...
 
Oesophagus <ul><li>Narrow muscular tube </li></ul><ul><li>Wall consists of 4 layers </li></ul><ul><li>-  outermost layer  ...
serous coat - moist and slippery - layer of blood vessels & connective tissues - antagonistic smooth muscle sub-mucous  co...
Peristalsis <ul><li>Definition:  Rhythmic wave-like contractions of the walls of the gut </li></ul><ul><li>Caused by antag...
*Peristalsis Muscles are  antagonistic ( i.e. when one relaxes the other contracts and vice versa)
Stomach <ul><li>distensible, muscular bag (thick, well developed muscular walls) </li></ul>
Stomach structure muscle contracts   -> entrance to small intestine closes   muscle relaxes   -> entrance to small intesti...
Gastric glands - produces mucus which coats the surface epithelium  - produces pepsinogen   - produces HCl
Gastric juice <ul><li>contains HCl + 2 enzymes </li></ul><ul><ul><li>rennin </li></ul></ul><ul><ul><li>pepsin  </li></ul><...
Question to ponder: <ul><li>Do you think the enzymes in the stomach are produced in an active or inactive state? </li></ul>
Inactive enzymes <ul><li>Suggest reasons why the enzymes need to be produced in the inactive form. </li></ul><ul><li>Ans: ...
Small Intestine duodenum jejunum ileum
Pancreas, gall bladder & small intestine Cardiac sphincter Pyloric sphincter
Gall bladder  <ul><li>yellowish green bag </li></ul><ul><li>stores bile produced by the liver </li></ul><ul><li>releases  ...
Emulsification <ul><li>It is the process whereby large globules of fat are broken down into smaller globules  </li></ul><u...
Pancreas <ul><li>Connected to duodenum by  pancreatic duct </li></ul><ul><li>Secretes  </li></ul><ul><ul><li>pancreatic ju...
Pancreatic juice <ul><li>Contains  </li></ul><ul><ul><li>pancreatic amylase </li></ul></ul><ul><ul><li>pancreatic lipase <...
Intestinal juice <ul><li>secreted by glands lining small intestine </li></ul><ul><li>contains </li></ul><ul><ul><li>sucras...
Summary: <ul><li>Pg.100 Biology Textbook </li></ul><ul><li>Chapter 6:Nutrition in Humans </li></ul><ul><li>*Summary of dig...
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Chapter 6 Nutrition in Humans Lesson 1 - The Need for Digestion

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Chapter 6 Nutrition in Humans Lesson 1 - The Need for Digestion

  1. 1. Nutrition in Mammals
  2. 2. Lesson Objectives: <ul><li>Holozoic nutrition </li></ul><ul><li>Introduction to the human digestive system </li></ul><ul><li>Digestion in the </li></ul><ul><li>- mouth </li></ul><ul><li>- stomach </li></ul><ul><li>- small intestine </li></ul><ul><li>Absorption in the intestines (small and large intestines) </li></ul>
  3. 3. Holozoic nutrition (feeding on ready made complex organic matter) <ul><li>Digestion : process where large food molecules are broken down into soluble and diffusible molecules that can be absorbed into the body cells </li></ul><ul><li>Absorption : process whereby digested food materials are taken into the body cells </li></ul><ul><li>Assimilation : process whereby some of the absorbed food materials are converted into new protoplasm or used to provide energy </li></ul>
  4. 4. Study tips: <ul><li>Always try to relate the structure of an organ with its function </li></ul><ul><li>This serves as an easy way of remembering digestion facts! </li></ul>Picture the organ in your mind Identify the structures present Function of organ derived from structures present
  5. 5. Overview of the human digestive system Mouth ↓ Oesophagus ↓ Stomach ↓ Small Intestines ↓ Large Intestines ↓ Rectum ↓ Anus Mouth Stomach Small Intestine Pancreas Gall bladder Oesophagus
  6. 6. Types of digestion <ul><li>Mechanical digestion </li></ul><ul><li>Break down particles into smaller pieces so as to increase the surface area for the action of enzymes. </li></ul><ul><li>Chemical digestion </li></ul><ul><li>Involves enzymatic reactions which digest the food into simpler chemical forms. </li></ul>
  7. 7. Buccal Cavity (Mouth) <ul><li>Mechanical digestion </li></ul><ul><li>large small </li></ul><ul><li>Chemical digestion </li></ul><ul><li>Starch maltose </li></ul>amylase *mastication
  8. 9. Oesophagus <ul><li>Narrow muscular tube </li></ul><ul><li>Wall consists of 4 layers </li></ul><ul><li>- outermost layer ( serous coat ) </li></ul><ul><li>-> moist & slippery (reduces friction when organs slide over each other) </li></ul><ul><li>- smooth muscle </li></ul><ul><li>- sub-mucous coat (layer of blood vessels & connective tissues) </li></ul><ul><li>- mucous layer </li></ul>longitudinal muscle circular muscle (antagonistic)
  9. 10. serous coat - moist and slippery - layer of blood vessels & connective tissues - antagonistic smooth muscle sub-mucous coat mucous layer
  10. 11. Peristalsis <ul><li>Definition: Rhythmic wave-like contractions of the walls of the gut </li></ul><ul><li>Caused by antagonistic action of muscles in gut wall </li></ul><ul><li>i.e. when circular muscles contract, longitudinal muscles relax </li></ul><ul><li>a. Causes the movement of content along the gut </li></ul><ul><li>b. enables food to be mixed with digestive juices </li></ul>
  11. 12. *Peristalsis Muscles are antagonistic ( i.e. when one relaxes the other contracts and vice versa)
  12. 13. Stomach <ul><li>distensible, muscular bag (thick, well developed muscular walls) </li></ul>
  13. 14. Stomach structure muscle contracts -> entrance to small intestine closes muscle relaxes -> entrance to small intestine opens
  14. 15. Gastric glands - produces mucus which coats the surface epithelium - produces pepsinogen - produces HCl
  15. 16. Gastric juice <ul><li>contains HCl + 2 enzymes </li></ul><ul><ul><li>rennin </li></ul></ul><ul><ul><li>pepsin </li></ul></ul>soluble caseinogen insoluble casein rennin proteins polypeptides pepsin
  16. 17. Question to ponder: <ul><li>Do you think the enzymes in the stomach are produced in an active or inactive state? </li></ul>
  17. 18. Inactive enzymes <ul><li>Suggest reasons why the enzymes need to be produced in the inactive form. </li></ul><ul><li>Ans: protect the stomach lining </li></ul>pepsinogen pepsin prorennin rennin HCl HCl
  18. 19. Small Intestine duodenum jejunum ileum
  19. 20. Pancreas, gall bladder & small intestine Cardiac sphincter Pyloric sphincter
  20. 21. Gall bladder <ul><li>yellowish green bag </li></ul><ul><li>stores bile produced by the liver </li></ul><ul><li>releases bile when it contracts via bile duct </li></ul><ul><li>QUESTION: Can bile digest food? </li></ul><ul><li>ANSWER: </li></ul><ul><li>Bile is not an enzyme , so it cannot digest food but it aids in digestion of fats (by emulsifying fats) </li></ul>
  21. 22. Emulsification <ul><li>It is the process whereby large globules of fat are broken down into smaller globules </li></ul><ul><li>How? </li></ul><ul><li>Bile lowers the surface tension of fats i.e. reduce the attractive forces between the fat molecules </li></ul><ul><li>This causes the fats to break into tiny fat droplets suspended in water , forming an emulsion (physical digestion) </li></ul><ul><li>Purpose of emulsification </li></ul><ul><li>-> increases s.a.:volume ratio </li></ul><ul><li>-> speeds up digestion by lipase to f.a. + glycerol </li></ul>
  22. 23. Pancreas <ul><li>Connected to duodenum by pancreatic duct </li></ul><ul><li>Secretes </li></ul><ul><ul><li>pancreatic juice (digestive function) </li></ul></ul><ul><ul><li>insulin (controls blood glucose conc. & carbohydrate utilization) </li></ul></ul>
  23. 24. Pancreatic juice <ul><li>Contains </li></ul><ul><ul><li>pancreatic amylase </li></ul></ul><ul><ul><li>pancreatic lipase </li></ul></ul><ul><ul><li>pancreatic trypsinogen (protease) </li></ul></ul>ALT
  24. 25. Intestinal juice <ul><li>secreted by glands lining small intestine </li></ul><ul><li>contains </li></ul><ul><ul><li>sucrase </li></ul></ul><ul><ul><li>maltase </li></ul></ul><ul><ul><li>enterokinase </li></ul></ul><ul><ul><li>erepsin </li></ul></ul><ul><ul><li>lipase </li></ul></ul><ul><ul><li>lactase </li></ul></ul>SME 2 LL polypeptides amino acids erepsin trypsinogen trypsin enterokinase proteins polypeptides trypsin
  25. 26. Summary: <ul><li>Pg.100 Biology Textbook </li></ul><ul><li>Chapter 6:Nutrition in Humans </li></ul><ul><li>*Summary of digestion in the human gut </li></ul>

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