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  1. 1. The Digestive System Presented By: Mrs. Nelson
  2. 2. Nutrition  Nutrition is the study of how food affects the function of living organisms.  Food contains nutrients.  Nutrients provide the energy and materials organisms need.  If organism’s cells are not provided with nutrients, the cells will not function properly.  Poor diet = poor cells
  3. 3. Six Categories of Nutrients Energy Suppliers  Carbohydrates  Lipids  Proteins Non-Energy Suppliers  Water  Vitamins  Minerals
  4. 4. Carbohydrates  Glucose is main source of carbohydrates for animals.  Glucose is easily converted to ATP.  Glucose is found in fruits, vegetables, grains, and dairy foods.  Many foods contain cellulose also known as “fiber.” Important for helping push food through the digestive tract.  Energy from food is measured in “calories.”
  5. 5. Lipids  Provide twice as much energy as carbohydrates.  Important for… 1) Making cell membranes 2) Hormone production 3) Myelin production 4) Protect organs and insulate body  Take long time to digest.  Too much fat in diet= excess energy = fat deposits.  Saturated fats (solid, contain single bonds) contain LDL cholesterol and build up on arteries.
  6. 6. Proteins  Proteins made of amino acids.  20 different amino acids.  Body can make 12/20 amino acids.  The other eight must come from food are called “essential amino acids.”  Proteins are materials needed for… 1) growth and repair. 2) skin and muscles. 3) regulatory (enzymes- insulin) and transport functions (hemoglobin– RBC).
  7. 7. Water  Most important nutrient.  Lubricates areas of body (blood, lymph, plasma, etc.)  Coolant for body.  Solvent for digestion.  Provides fluid environment for cells.  Body needs intake 1L of water a day.
  8. 8. Minerals  Inorganic (not made by living things).  Plants absorb minerals.  Animals eat plants to get minerals.  Minerals are only needed in trace amounts by the body.  Iron (hemoglobin RBC)  Calcium (bones and teeth)  Sodium/Potassium (nerve and muscle function)  Magnesium/Zinc/Iodine
  9. 9. Vitamins  Organic (made by living things).  Help regulate body processes.  Most obtained from food.  Vitamin K- made by bacteria in digestive tract.  Vitamin D- synthesized by skin cells when exposed to sunlight.  2 types vitamins… 1) Fat soluble- can be stored in fatty tissues for future use (A, D, E, K) 2) Water soluble- dissolve in water and can not be stored by body (C, B)
  10. 10. Importance of Various Vitamins  A, C, D, E, K, Folic Acid, B12 Helps RBC mature
  11. 11. The Digestive System  System is responsible for breaking down food so that nutrients can be absorbed by the bloodstream.  The “alimentary canal” is the pathway which food travels while it is digested.
  12. 12. The Alimentary Canal  Mouth  Esophagus  Stomach  Small intestine  Large intestine  Rectum * The liver, pancreas, and gallbladder are parts of the digestive system but are not parts of the alimentary canal.
  13. 13. The Mouth  Chemical digestion –saliva contains enzyme amylase that digests carbohydrates (starches)  Mechanical digestion- chewing
  14. 14. Esophagus  Tube from back throat to stomach.  Trachea (lungs) and esophagus are next to each other.  Epiglottis prevents food from going down the wrong tube.  Peristalsis- muscular contractions pushes food down esophagus.
  15. 15. Stomach  Chemical/mechanical digestion.  Hydrochloric acid and pepsin (enzyme) break down proteins to amino acids.  Stomach lining contains mucus.  Mucus protects stomach from acid (ulcers).  Sphincter muscles (cardiac and pyloric) control what enters and leaves the stomach (heartburn).
  16. 16. Small Intestine  20 ft.  Remaining carbohydrates and proteins are broken down.  All lipids are digested here.  Connected to liver and pancreas.
  17. 17. Liver and Pancreas LIVER JOBS  Makes and secretes bile (needed digest lipids).  Bile is stored in the gall bladder.  Detoxifies drugs and alcohol. PANCREAS JOBS  Regulates blood sugar.  Secretes digestive enzymes into small intestine.  Neutralizes stomach acid as it enters the small intestine (bicarbonate).
  18. 18. Small Intestine (cont.)  After all nutrients are digested, they are absorbed. This is the major job of this organ.  S.I. contains lots of capillaries.  Mesentary.
  19. 19. Large Intestine  All proteins, carbohydrates, and lipids have been removed from food by the time it gets here.  Water is absorbed (diarrhea).  Vitamins are absorbed.  Feces is undigested food passes out rectum and anus.