Digestive System Teacher


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Digestive System Teacher

  1. 1. The Digestive System Bleecker-Style 
  2. 2. Table of Contents <ul><li>Cells, Tissues, Organs, Organ Systems </li></ul><ul><li>Introduction to the Digestive System </li></ul><ul><li>What is Digestion? </li></ul><ul><li>2 Phases of Digestion </li></ul><ul><li>4 Components of Digestion </li></ul><ul><li>The Organs of Digestion </li></ul>
  3. 3. How the Body is Organized 1. Cellular Level - Individual cells are the basic building blocks of life 2. Tissue level - Tissue is formed when groups of cells act together 3. Organ Level - An organ is a system of tissues working together 4. System Level - Many organs acting together form a system, such as the DIGESTIVE SYSTEM
  4. 4. Introduction to the Digestive System <ul><li>The digestive system is an organ system that ingests food, breaks it down into smaller chemical units, and absorbs the nutrient molecules. </li></ul>
  5. 5. What is Digestion? <ul><li>Digestion is the mechanical and chemical breakdown of food into molecules small enough for the body to absorb. </li></ul>
  6. 6. 2 Phases of Digestion <ul><li>Mechanical Digestion – begins in the mouth where the food is chewed. </li></ul><ul><li>- Saliva = watery fluid making it easier to swallow. Also some enzymatic digestion of starch </li></ul><ul><li>Chemical Digestion – occurs in the mouth and the stomach. HCl produced by the stomach cells. </li></ul>
  7. 7. 4 Components of Digestion <ul><li>Ingestion – the intake of nutrients </li></ul><ul><li>Digestion – the breakdown of organic molecules </li></ul><ul><li>Absorption – the transport of digested nutrients to body tissues </li></ul><ul><li>Egestion – the removal of materials from food that the body cannot digest </li></ul>
  8. 8. The Organs of Digestion
  9. 9. Mouth <ul><li>Physical digestion begins </li></ul><ul><li>Food is chewed into a bolus and mixed with saliva </li></ul><ul><li>Initial carbohydrate digestion </li></ul>
  10. 10. Parts of the Mouth 20 Baby Teeth 32 Adult Teeth Wisdom Teeth …
  11. 12. Salivary Glands in the Mouth
  12. 13. Swallowing and the Epiglottis Air enters via pharynx The epiglottis is a flap of tissue that has a very important job It covers the trachea when swallowing to prevent food to lungs It covers the esophagus when we breath, so air goes to lungs
  13. 15. Esophagus <ul><li>Peristaltic contractions move the food from the mouth to the stomach through the esophagus. </li></ul>
  14. 16. Stomach <ul><li>Food storage </li></ul><ul><li>Initial protein digestion </li></ul><ul><li>Mechanical digestion grinding by muscles </li></ul><ul><li>Chemical breakdown of food by HCl </li></ul>
  15. 17. Stomach Protection from Acid <ul><li>What protects stomach from digesting itself? </li></ul><ul><li>HCl is nasty! </li></ul><ul><li>Answer: cells also secrete mucus that acts as a barrier! </li></ul>
  16. 18. Stomach Ulcers OUCH!
  17. 19. Small Intestine <ul><li>Site of the majority of digestion and absorption </li></ul><ul><li>Digestion of proteins, carbohydrates, and lipids </li></ul><ul><li>Folds of small intestine increase the SA for absorbing nutrients </li></ul>
  18. 20. Small Intestine in Cross Section SA is increased by fingerlike projections called VILLI These do the actual absorbing of fats, proteins and carbohydrates
  19. 21. Villi Close up
  20. 23. Small Intestine – 3 Sections Stomach to 1. Duodenum to 2. Jejenum to 3. Ileum
  21. 24. Focus on the Duodemum
  22. 25. Enzyme Action in Duodemum <ul><li>Bile from Liver is received from the Gallbladder (green) </li></ul><ul><ul><li>The bile is used as an emulsifier to help the body absorb fats </li></ul></ul><ul><li>Lipase from the Pancreas breaks down fats into fatty acids </li></ul><ul><li>Trypsin is activated by acid from the stomach, and digests the protein further into amino acids </li></ul><ul><li>Pancreatic Amylase – digests carbohydrates </li></ul>
  23. 26. Regulating Digestive Secretions <ul><li>Gastrin </li></ul><ul><ul><li>Produced by stomach when churns </li></ul></ul><ul><ul><li>Inhibited by duodenal response </li></ul></ul><ul><li>Duodenum secretes GIP (gastro-inhibatory peptides) to turn off gastrin production in stomach (neg loop) </li></ul><ul><li>Duodenum also produces CCK (cholecystokinin) in response to partly digested fat and protein as well as secretin that increase the output of bile from liver and pancreatic juice. </li></ul>
  24. 27. Classic Feeback Loop - CCK stimulates liver and pancreas
  25. 28. Note that in Stomach, HCl Activates an Enzyme <ul><li>Acid activates Pepsin so that protein is digested. </li></ul><ul><li>Hormone GASTRIN is secreted and sent through blood to brain to suppress appetite! </li></ul>
  26. 29. Pancreas <ul><li>Releases enzymes such as </li></ul><ul><li>Amylase </li></ul><ul><li>Lipase </li></ul><ul><li>into the small intestine to aid in digestion </li></ul>
  27. 30. Liver <ul><li>Produces bile salts which emulsify fats </li></ul><ul><li>Storehouse for glycogen(starch) and vitamins </li></ul><ul><li>Detoxifies many substances in the body (alcohol, poisons, etc) </li></ul>
  28. 31. Gall Bladder <ul><li>Stores bile salts </li></ul>
  29. 32. Large Intestine <ul><li>Stores food wastes long enough to reabsorb water </li></ul><ul><li>Forms the stool, aka POOP </li></ul><ul><li>Houses bacteria which use waste materials to synthesize vitamins </li></ul>
  30. 33. 3 Regions of Large Intestine you must Know
  31. 34. AssiGnments <ul><li>Ensure that The Breakdown Video Wkst. is done and handed in before you leave. </li></ul><ul><li>Complete Chp Review on pg. 148 #C1,C2,C4,C6,C7. </li></ul><ul><li>Readings: (relax, they’re like the notes we just did) </li></ul><ul><li>Chapter notes for 7.3 & 7.4 (pg’s 140-148) </li></ul><ul><li>Color the rest of the digestive system handout! Know it, because you will be quizzed on it  </li></ul>