The Digestive System


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The Digestive System

  1. 1. <ul><li>THE DIGESTIVE SYSTEM </li></ul>
  2. 2. <ul><li>The human body needs fuel to live. The food we eat gives us fuel. However, the food must be broken down into chemicals that the body can use. This process is called DIGESTION . </li></ul>
  3. 3. <ul><li>Some of the organs involved in digestion are: </li></ul><ul><li>1). The mouth </li></ul><ul><li>2). The oesophagus </li></ul><ul><li>3). The stomach </li></ul><ul><li>4). The small and large intestines </li></ul><ul><li>5). The gallbladder, pancreas and liver. </li></ul>
  4. 5. <ul><li>The first place where food starts to break down is in the mouth . </li></ul><ul><li>During the process of chewing, food is broken down to smaller pieces. The front teeth cut the food and the back teeth grind the food. </li></ul><ul><li>The secretion of saliva in the mouth helps to break down the food. It contains an enzyme called amylase which helps to break down the starch in the food. </li></ul>
  5. 6. <ul><li>After the food is chewed, it is swallowed and passes down the oesophagus to the stomach. </li></ul><ul><li>The oesophagus is about ten inches long. The tongue helps to push the food to the back of the mouth, and the muscles in the oesophagus send the food down the tube. </li></ul>
  6. 8. <ul><li>When food enters the stomach , it is mixed with gastric acid which contains hydrochloric acid. This acid together with muscle movement in the stomach helps break down the food. The stomach wall is separated from the acid by a thin lining. </li></ul><ul><li>From the stomach, the food pulp is sent to the small intestine a little bit at a time. </li></ul>
  7. 10. <ul><li>The small intestine is about twenty feet in length and one inch in diameter. It is the final place for digestion. </li></ul><ul><li>Digestive juices are released in the small intestine to finish breaking down the food. </li></ul><ul><li>The food is moved along the small intestine in a squeezing motion known as peristalsis. This motion is similar to squeezing a tube of toothpaste. </li></ul>
  8. 11. <ul><li>The small intestine are lined with millions of little projections called villi. These absorb the chemicals that we need from the food into the body. This is the point where the food is actually in the body. </li></ul><ul><li>Waste products and food which are not absorbed in the small intestine pass into the large intestine. </li></ul>
  9. 13. <ul><li>The large intestine is only five feet long but has a larger diameter than the small intestine and includes the colon. </li></ul><ul><li>Waste material entering it are called faeces. Faeces are formed from water, undigested food and bacteria. </li></ul><ul><li>In the large intestine, water is absorbed back into the body so the waste material becomes more solid as it travels through the colon. This process can take up to twenty hours before food passes completely through the large intestine. </li></ul>
  10. 15. <ul><li>The pancreas is an elongated gland found below the stomach and produces pancreatic juice which contains digestive enzymes. </li></ul><ul><li>The pancreas also secrets insulin into the blood which is needed to allow glucose or sugar from food to get into the bloodstream. </li></ul><ul><li>People who cannot produce insulin are diabetics </li></ul>
  11. 16. <ul><li>The largest organ in the body is the liver . It weighs about three pounds and is eight inches long. The liver stores a form of glucose called glycogen and produces a substance called bile which is needed to breakdown fat. </li></ul><ul><li>This organ is also where alcohol, drugs, bacteria and old blood cells are broken down and removed from the body. </li></ul>
  12. 17. <ul><li>The gallbladder is a small sac on the underside of the liver. It stores bile which is made by the liver. Bile travels from the liver through the hepatic ducts to the gallbladder. </li></ul><ul><li>Bile is needed to break down fat present in the food. </li></ul>
  13. 18. <ul><li>THE END </li></ul>