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The Digestive System

The Digestive System. Introduction. Activator: Can you identify the organs of the digestive system?. The Digestive System. The Digestive System. What is the primary role of the digestive system?. To break down the food we eat into molecules that the body can use in order to produce energy.

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The Digestive System

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  1. The Digestive System Introduction

  2. Activator: Can you identify the organs of the digestive system?

  3. The Digestive System The Digestive System

  4. What is the primary role of the digestive system? • To break down the food we eat into molecules that the body can use in order to produce energy

  5. What are the four stages of food processing? • Ingestion • Digestion • Absorption • Egestion

  6. Ingestion: • The taking in of food – eating!

  7. Digestion • Process by which your body breaks down food into small nutrient molecules

  8. Absorption • When nutrient molecules pass through the wall of your digestive system into the blood

  9. Egestion • Elimination of wastes from the body – poop! • Wastes are any materials not absorbed by the body

  10. What is mechanical digestion? • Foods are physically broken down into smaller pieces • Example: • when you bite into a sandwich and chew it into small pieces

  11. What is chemical digestion? • Enzymes produced by the body break down foods into their smaller chemical building blocks • Examples: • Starch into Individual Sugars • Proteins into Amino Acids

  12. How are enzymes involved in chemical digestion? • Chemical digestion is accomplished by enzymes • An enzyme is a protein that speeds up chemical reactions in the body

  13. Three types of Digestive Enzymes Digestive Enzymes http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related

  14. What does the term “peristalsis” mean? • Involuntary waves of muscle contraction that pushes food in one direction through the digestive tract • What is reverse peristalsis? • VOMITING

  15. Activator: What did you eat for lunch today? Which stage of food processing does this describe? INGESTION!

  16. Where does digestion begin? THE MOUTH! What types of digestion take place in the mouth?

  17. Mechanical Digestion in the Mouth • Your TEETH cut the food into bite-sized pieces • SALIVA in your mouth moistens the food

  18. Chemical Digestion in the Mouth • Chemical Digestion of STARCH (carbohydrates) begins in the mouth • What is the name of the enzyme that is active? • Salivary Amylase

  19. Amylase Amyase

  20. Why can’t you breath and swallow at the same time? • The epiglottis seals off your windpipe when you swallow Where does the food go next?

  21. Esophagus Long muscular tube that connects the stomach to the pharynx (upper portion of the throat). Peristalsis occurs here

  22. Does digestion take place in the esophagus? NO! The Oeophagus

  23. What type of digestion takes place in the stomach? • Mechanical – Churning of the food which moistens and makes it smaller • Chemical – Digestion of proteins by Pepsin (a protease)

  24. What are the two major secretions of the stomach glands? Stomach Glands Pepsin (a protease) Digestion of proteins HCL (Hydrochloric Acid) Acidic pH Kill Bacteria Enzyme specificity

  25. Protease Protease

  26. What is the optimum pH and temperature for pepsin? Optimum pH = 2 Optimum Temp = 40

  27. Which stomach will work? 1 = water 2 = water + pepsin 3 = water + acid 4 = acid + pepsin

  28. Quick Review • What types of digestion occur in the mouth? • Does any digestion occur in the esophagus? • What types of digestion occurs in the stomach? • Will pepsin be functional outside of the stomach? Why? • What is the term used to describe the muscle contractions that moves food through the digestive system?

  29. What are the two major functions of the Small Intestine? • Responsible for the completion of digestion and absorption of nutrients.

  30. What enzymes are active in the small intestine during digestion? • Amylases • Proteases • Lipases • Do these enzymes perform mechanical or chemical digestion? • CHEMICAL DIGESTION!

  31. Where are these enzymes produced? • The pancreas! • Pancreatic juice is secreted directly into the small intestine

  32. Bile Production and Storage • Produced by the liver • Stored in the gallbladder

  33. Bile • Emulsification: breaking down large fats into smaller fats to increase surface area • Is this mechanical or chemical? • MECHANICAL DIGESTION!

  34. What is an accessory organ? A structure that provides a substance that aids in digestion, but no food passes through it.

  35. What are the four accessory organs of the digestive system? • Salivary Glands • Liver • Gallbladder • Pancreas

  36. **All ___________ is completed in the first 1/3 of the small intestine** DIGESTION **The remaining 2/3 of the small intestine is responsible for ___________** ABSORPTION

  37. Absorption How is the structure of the small intestine ideal for absorption? • Its very long (about 21 feet) • Many folds • Has many villi that are lined with blood vessels

  38. Once absorbed by the villi, where do the nutrients go? Blood Vessels (circulatory system) carry nutrients to the body cells!

  39. Large Intestine • Undigested material passes into the L.I • No digestion occurs here • The major function is to reabsorb water & vitamins. • Stores waste in the rectum. • Egests through the anus.

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