1. 1 DIGESTIVE SYSTEM - Transfers nutrients, salts, H 2 O and vitamins in food from external to internal environment Anatomy: Digestive tract (gastrointestinal (GI) tract) Mouth -> Pharynx -> Esophagus -> Stomach -> Small intestine -> Large intestine -> Anus

2. 2 DIGESTIVE SYSTEM Digestive System: Mouth: - teeth = mastication (incisors, canines, molars) -3 pairs salivary glands secrete saliva: 1) moistens and lubricates food 2) amylase

3. 3 DIGESTIVE SYSTEM Digestive System Organs Pharynx and Esophagus - transport food and water to stomach - swallowing reflex: epiglottis As food approaches stomach, sphincter relaxes so food can go into stomach Sphincter closes -> Prevents acid reflux

4. 4 DIGESTIVE SYSTEM Digestive System Organs Stomach - STORES food - gastric juice = pepsin (Enzyme) and HCl (low pH!) - Digestion/churning - No Absorption of food - Gastric mucosal barrier (thick)

5. 5 Small Intestine - Most digestion occurs here - Digestion by small intestine & pancreatic enzymes - Most absorption = villi: contains capillaries & a lacteal DIGESTIVE SYSTEM Digestive System Organs

6. 6 Small Intestine Digestion in small intestine depends on substances secreted by 3 accessory organs: i) Pancreas - pancreatic juice = digestive enzymes 1. pancreatic amylase 2. trypsin 3. lipase (another function?)

7. 7 DIGESTIVE SYSTEM Digestive System Organs Small Intestine Digestion in small intestine depends on substances secreted by 3 accessory organs: ii) Liver 1) secretes bile salts 2) metabolic processing 3) detoxification 4) stores glycogen, fats, minerals, vitamins What is glycogen? Why is it important?

8. 8 DIGESTIVE SYSTEM Digestive System Organs ii) Liver - Bile = bile salts, but they are stored in… iii) Gallbladder Bile => emulsification of fat -> Digest fat -> Absorbed into lacteal *** Nutrient-rich blood from Small Intestine -> Hepatic Portal System

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10. 10 DIGESTIVE SYSTEM Digestive System Organs 5)Large Intestine 5 x longer to move through than small intestine mass movements (every 8-12 hrs; more often after meals) absorption of salts/water, secretion of mucus, microorganism activity

11. 11 DIGESTIVE SYSTEM Control of Digestion A. Neural -Involuntary nervous system -Sight and SMELL stimulate gastric juices (stomach) via neural activity

12. 12 DIGESTIVE SYSTEM Nutrition B. Micronutrients are also required: 1) Vitamins - 13 different vitamins - Vitamin D => bone strength - Vitamin C => immune system

13. 13 DIGESTIVE SYSTEM Nutrition 2) Minerals a) Macrominerals - more than 100 mg/day - includes:sodium magnesium phosphorus chlorine potassium calcium

14. 14 DIGESTIVE SYSTEM Nutrition 2) Minerals b) Microminerals - less 20 mg/day - very specific functions - e.g., iron => hemoglobin iodine => thyroid hormone