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Digestive System

Digestive System. Anatomy and Function Functions Convert food into smaller molecules that can be absorbed by cells Remove solid waste B. 2 Major components 1. The Alimentary Canal (your food tube) 2. Digestive glands How does digestion relate to cellular respiration?. Digestive System.

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Digestive System

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  1. Digestive System • Anatomy and Function • Functions • Convert food into smaller molecules that can be absorbed by cells • Remove solid waste B. 2 Major components 1. The Alimentary Canal (your food tube) 2. Digestive glands • How does digestion relate to cellular respiration?

  2. Digestive System II. The Alimentary Canal • Mouth – Two types of digestion • Mechanical digestion – Tear & crush food (chewing) • Chemical digestion • Saliva – produced by salivary glands, moisten food making it easier to chew • Contains amylase (breaks down carbs) and lysozyme (kills bacteria)

  3. Digestive System • Pharynx (throat) • Connects mouth to esophagus • Swallow chewed up food ball called a bolus • Epiglottis covers the trachea – Why? Epiglottis

  4. Digestive System • Esophagus • Moves food to the stomach by peristalsis(Fig. 38-11) • Cardiac Sphincter • Thick ring of muscle that closes the esophagus after food enters the stomach. • Why is this important? • Heartburn • What causes it?

  5. Digestive System • Stomach • Food mixes with hydrochloric acid (HCl) and pepsin to form chyme.

  6. Digestive System • HCl activates pepsin • Pepsin breaks down large protein molecules into small chains of ???? • What protects the stomach from pepsin and HCl?

  7. Digestive System • After 1-2 hours, pyloric valve opens and chyme flows into the small intestine. What is pyloric stenosis?

  8. Digestive System F. Small Intestine • This is where most of your food is digested and absorbed 3 Sections: • Duodenum (~ 1 foot long) • Digestive enzymes from the pancreas and the liver are added to the food. • The gallbladder adds bile • The pancreas adds sodium bicarbonate is also added…WHY?

  9. Digestive System • Jejunum (~ 3 feet) and Ileum (~ 6 feet) • The inside of the intestine is not smooth but has many small folds called villi and the villi have many microscopic folds called microvilli. • Why all of the folds? • Once absorbed, how do nutrients get to cells? Villi Microvilli

  10. Where is your appendix? Appendix

  11. Digestive System • Large Intestine (Colon) • Reabsorbs water from undigested material What happens when too much water is absorbed? Too little? • Bacteria in colon produce Vitamin K and live off undigested organic material (e.g. E. coli) • Bacteria generate gases (methane and hydrogen sulfide) as a by-product of their metabolism  • Remaining undigested material (feces) is excreted through the rectum and anus

  12. Large Intestine (Colon)

  13. Alimentary Canal (Gastrointestinal “GI” Tract) 1.Mouth 2. Pharynx 3. Esophagus 4. Stomach 6.Large Intestine 5.Small Intestine 7. Rectum

  14. Accessory Organs 8. Salivary Glands 10. Liver 9. Pancreas (behind stomach) 11. Gall Bladder

  15. III. Digestive Glands • Liver • Detoxifies the blood • Stores vitamins and minerals • Converts foodstuffs from one form to another • Produces bile

  16. III. Digestive Glands (cont) • Gall Bladder 1. Stores and releases bile 2. Bile emulsifies fats • Pancreas • Produces ???? And ???? Digestion Recap…

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