Comprehensive Digestive System Study Guide

1. Study guide… • Match the layers of the GI tract to their location and type of tissue they contain. • Identify the enzymes that digest each nutrient and their location. • Describe the role of pH in digestion. • List the parts of the small and large intestine in order. • Describe how villi aids in absorption in the small intestine.

2. Study guide… • Describe the digestive role of the pancreas and liver. • Describe how the nervous and endocrine systems regulate digestion. • Apply the nutritional guidelines for carbohydrates, lipids and proteins.

3. Digestive System ACCESSORY ORGANS: ORGANS: Mouth Pharynx Salivaryglands Esophagus Stomach Liver Smallintestine Gallbladder Pancreas Largeintestine Appendix Sigmoidcolon Rectum Anus Figure 14.1

4. Gastrointestinal (GI) Tract LayersFrom the lumen…Name the 4 layers • Mucous membrane • Connective, nervous, blood vessels • Smooth muscle • Serous membrane • Secretes mucus, digestive enzymes, acid; absorbs • Carries nutrients • Movement from esophagus to anus • Secretes lubricating fluid

5. Gastrointestinal (GI) Tract Wall Vein Lymph vessel Artery Nerve Serosa Muscularis Lumen Submucosa Mucosa Figure 14.2

6. The Mouth • Saliva • Salivary glands • Parotid • Submandibular • Sublingual • What enzyme digests carbohydrates in the mouth? • The tongue forms a bolus and moves it into the pharynx.

7. Swallowing and peristalsis Figure 14.3a

8. Structure of the Stomach Wall What cells line the pits? Figure 14.7a–b

9. Stomach Function • Specific cells secrete gastric juice • Hydrochloric acid • Produces a pH of about 2; activates pepsinogen • Mucus • Protects stomach lining from acid • Pepsinogen • What activated enzyme begins protein digestion? • Helicobacter pylori • Chyme enters the small intestine after 2-6 hours.

10. Peristalsis What muscles are involuntarily churning your food? Figure 14.8

11. Small Intestine • Functions • Digestion • Neutralizes acid from stomach • Adds digestive enzymes and bile • Breaks proteins, carbohydrates, and lipids to absorbable materials • Absorption • 95% of food absorbed in small intestine

12. Small Intestine • Structure • Duodenum • Jejunum • Ileum • Mucosa adaptations • Villi containing blood and lacteal capillaries

13. Accessory Organs: Aid Digestion and Absorption • Liver • Produces bile (What stores it?) • Hepatic portal • Drains blood from digestive tract to liver

14. Accessory Organs: Aid Digestion and Absorption Figure 14.11

15. Accessory Organs: Aid Digestion and Absorption • Pancreas • Exocrine functions • Secretes digestive enzymes and sodium bicarbonate • Which enzyme acts on carbohydrates? • Proteins? • Fats?

16. Absorption of Proteins and Carbohydrates Figure 14.13

17. Absorption of Fats Figure 14.14

18. Large Intestine: Structure and Function • Functions • Absorbs water and vitamins • Eliminates waste • Structure • Cecum, appendix • Colon • Rectum, anus

19. Endocrine and Nervous Systems Regulation of Digestion • Regulation dependent on volume and content of food • Nervous system • Stretch receptors in stomach • Hormones • Gastrin • Secretin • Cholecystokinin (CCK)

20. Carbohydrates • Digested into glucose • Pancreas secretes insulin • Insulin binds to receptors on cells • Glucose can now enter cells to make ATP • What if your insulin receptors become less sensitive? • Cells scream at pancreas to release more insulin • High insulin leads to higher blood pressure, high cholesterol and fat deposition • Increased risk of type 2 diabetes, heart disease and liver problems

21. What changes can you make today? • Exercise-helps insulin attach to receptors • Get lean-Fat cells sabotage muscle cells • Eat original, whole grain vs. refined, processed • Insulin receptors work best if you keep your blood sugar steady • Eat fiber • Slows down sugar absorption process • Friend to your digestive tract • Aim for 25-35 grams per day

22. Proteins • Made of amino acids • 9 essential amino acids can not be made by the body • 11 nonessential amino acids can be made by the body if the building blocks are there • Come from plant and animal sources • Animal sources and soy provide all 9 essential amino acids • Empties stomach slowly and leaves you feeling full longer • What if you eat more protein that what you need? • Deposited as body fat

23. What changes can you make today? • Eat 0.8grams of protein per kg of body weight. • Choose wisely • Fish, shellfish, skinless (white meat) poultry • Lean beef (>85%) with visible fat removed • Beans, lentils, tofu, peanut butter, seeds • Grill, bake, broil, roast, poach, stir fry

24. Lipids • Fats help to maintain healthy skin, hairand transports vitamins (ADEK) • Saturated vs. Unsaturated • Trans-fatty acids • reduce the ability of cells to clear cholesterol from the bloodstream • High density lipoproteins (HDL) cholesterol • carries cholesterol to the liver where it is converted to bile salts • Low density lipoproteins (LDL) cholesterol • Deposits within walls of arteries and increases risk of heart attacks and stroke

25. What changes can you make today? Limit saturated fats • Found in animals and processed snack food • Avoid trans fats • Ingredient list will say hydrogenated • Limit cholesterol to 300 mg per day • Choose unsaturated fats • Found in most plants, nuts, seeds and fish • Choose polys and monos • Include omega fatty acids • Don’t smoke…it will increase your LDLs and lower your HDLs