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  1. 1. ND Sports and Exercise Science Unit 12 – Nutrition Outcome 1b – The digestive system
  2. 2. Outcomes <ul><li>To understand the basic functions of the digestive system </li></ul><ul><li>To be able to name the organs involved in the digestive system </li></ul>
  3. 3. What is Digestion? <ul><li>A process by which nutrients and minerals are digested and passed through the body </li></ul><ul><li>Divided in to two groups of organs </li></ul><ul><li>The digestive tract – from the mouth to the anus </li></ul><ul><li>The accessory Organs – necessary for the system to work but not on the tract </li></ul>
  4. 4. The digestive system – basics
  5. 5. Organs involved <ul><li>Buccal cavity – mouth </li></ul><ul><li>Oesophagus </li></ul><ul><li>Stomach </li></ul><ul><li>Duodenum </li></ul><ul><li>Small intestine </li></ul><ul><li>Pancreas </li></ul><ul><li>Liver </li></ul><ul><li>Gall bladder </li></ul><ul><li>Large intestine </li></ul><ul><li>Rectum </li></ul><ul><li>Anal canal </li></ul>
  6. 6. Task <ul><li>In pairs jot the functions of each organ in the digestive system on post it notes </li></ul><ul><li>One post it note to each organ </li></ul>
  7. 7. Mouth and Oesophagus <ul><li>Digestion starts in the mouth (buccal cavity). Teeth and jaws grind food to mix it with saliva, which contains the enzyme amylase that begins the breakdown of starch. </li></ul><ul><li>The food is swallowed, enters the oesophagus, which connects the mouth to the stomach, it is squeezed along the oesophagus by a process called peristalsis. </li></ul>
  8. 8. Peristalsis <ul><li>Muscular movement of food through the digestive tract </li></ul>
  9. 9. Stomach <ul><li>It takes around 3-6 seconds for food to travel from your mouth to your stomach </li></ul><ul><li>Lining your stomach are cells that produce and release gastric juices containing enzymes and hydrochloric acid, which helps to break down the food and kill any bacteria in it. </li></ul><ul><li>Food normally retains in your stomach for 1-4 hour but fluid will pass through more rapidly </li></ul>
  10. 10. Stomach <ul><li>Serves as a storage pouch, digestive organ and churn </li></ul><ul><li>Stomach can stretch to hold 12 pints of liquid and food </li></ul><ul><li>Cells produce gastric juices and acids that breaks food </li></ul><ul><li>The mixed food and gastric juice leaves the stomach as chyme </li></ul><ul><li>On to the small intestine </li></ul>
  11. 11. Duodenum and small intestine <ul><li>Stomach the chyme passes to your duodenum and then to your small intestine, a tube of about six metres length </li></ul><ul><li>The duodenum is the start of the small intestine, and curves around the pancreas </li></ul><ul><li>As the chyme enters your small intestine it is mixed with more digestive juices, from the pancreas. </li></ul><ul><li>Pancreatic juices contains bile made by the liver as well as enzymes to further assist the breakdown of macronutrients. </li></ul>
  12. 12. Small Intestine <ul><li>Longer in length than the large intestine but is smaller in diameter than the large </li></ul><ul><li>Lined with thousands of villi that absorb the digested food, water and minerals </li></ul>
  13. 13. Liver <ul><li>Manufactures bile </li></ul><ul><li>Stores glycogen </li></ul><ul><li>Modifies fats </li></ul><ul><li>Storage of vitamins and iron </li></ul><ul><li>Detoxification of harmful substances – alcohol and drugs! </li></ul>
  14. 14. Bile <ul><li>Main function of the liver is to produce bile </li></ul><ul><li>Bile processes fats </li></ul><ul><li>Bile travels from the liver to the gallbladder and then in to the duodenum </li></ul>
  15. 15. Pancreas <ul><li>Produces enzymes that digests fat, protein and carbohydrates </li></ul><ul><li>Produces insulin and glucagon that regulate sugar metabolism </li></ul><ul><li>Released in to the blood </li></ul>
  16. 16. Gall Bladder <ul><li>Liver produces bile though out the day </li></ul><ul><li>Body only needs it a few times a day </li></ul><ul><li>Gall bladder stores it and provides when needed bile through the duodenum </li></ul>
  17. 17. Gall Bladder <ul><li>Stores and concentrates bile until it is required for digestion </li></ul><ul><li>It is then released in to the digestive tract to emulsify fats and neutralise the acids in partly digested foods </li></ul><ul><li>Peristalsis continues to move the chyme through your digestive system to your large intestine </li></ul>
  18. 18. Large intestine <ul><li>No food is digested here – some water is re-absorbed </li></ul><ul><li>The undigested food is stored as faeces </li></ul><ul><li>Bacteria in your large intestine produces vitamin k </li></ul><ul><li>The residue left behind is passed to the rectum and anal canal and is excreted as faeces </li></ul>
  19. 19. Large Intestine
  20. 20. Function of the digestive system <ul><li>So, what are the main functions of the digestive system? </li></ul><ul><li>Digestion </li></ul><ul><li>Absorption </li></ul><ul><li>Excretion </li></ul>
  21. 21. Digestion <ul><li>The first stage </li></ul><ul><li>Multi stage process </li></ul><ul><li>Mechanical and chemical elements </li></ul><ul><li>Enzymes in the gut breaking down raw matter in to smaller compounds for your bodies to absorb </li></ul>
  22. 22. Absorption <ul><li>Movement of digested food from your stomach and small intestine into your body tissues and blood </li></ul><ul><li>Happens in the villi that line the large intestine </li></ul><ul><li>Each villus has a large network of capaliries to support this absorption </li></ul><ul><li>Amino acids (from proteins) and glucose (from carbs) = blood stream directly </li></ul><ul><li>Fatty acids and glycerol (both from fats) = lymphatic system </li></ul>
  23. 23. Excretion <ul><li>Removal of potentially poisonous end produce through urine and faeces </li></ul><ul><li>Kidneys = urine is eliminated and passed to your bladder </li></ul><ul><li> </li></ul><ul><li>Large intestine = passes solid matter </li></ul>
  24. 24. Task <ul><li>Using the cards and diagrams order the organs involved in the digestion process </li></ul><ul><li>Label the blank diagram </li></ul><ul><li>Produce a table outlining the function of each organ </li></ul>
  25. 25. References and resources <ul><li> </li></ul><ul><li>Memmler’s human body in health and disease, B. Cohen Lippincott, Williams and Wilkins 2005 </li></ul>