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Digestion & Nutrition Chapter 15. Mouth. Teeth: mechanical digestion Incisors Canines Molars Salivary glands: chemical digestion Moisten food Start digesting carbohydrates. Pharynx and Esophagus. Pharynx: Connects nasal and oral cavities with larynx and esophagus
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Mouth • Teeth: mechanical digestion • Incisors • Canines • Molars • Salivary glands: chemical digestion • Moisten food • Start digesting carbohydrates
Pharynx and Esophagus • Pharynx: • Connects nasal and oral cavities with larynx and esophagus • 3 parts (see Fig.15.6): • Nasopharynx • Oropharynx • Laryngopharynx
Pharynx and Esophagus • Esophagus • Tube connecting pharynx and stomach • Peristaltic waves carry food down the tube • Lower esophageal sphincter closes entrance to the stomach to prevent reflux of stomach contents
Stomach • About 1 L capacity • Divided into 4 regions: • Cardiac region – near esophageal opening • Fundic region – “top curve”; temporary storage area • Body region – main part • Pyloric region – narrowing at bottom; pyloric sphincter closes off bottom of stomach
Stomach, continued….. • Chyme: semifluid paste of food particles and gastric juice formed in the stomach • Chyme exits the stomach at different rates, depending on components: • Fluids pass quickly • Fatty foods spend 3-6 hours in the stomach • Proteins move more quickly • Carbohydrates move faster than other foods
Stomach, continued….. • Ulcers • What are they? • What causes them? • What is the difference between a gastric ulcer and a duodenal ulcer?
Pancreas • Both an endocrine and exocrine gland • Secretes pancreatic juice into the duodenum (c-shaped beginning of small intestine), through the pancreatic duct
Pancreas, continued….. • What would be the effects of an improperly functioning pancreas? • Cystic fibrosis and the pancreas
Pancreatitis • Caused when pancreatic juice is blocked from release into the duodenum • Trypsinogen digests part of the pancreas • Can be caused by alcoholism, gallstones, trauma, medications
Liver Heaviest organ in the body ~ 3 lbs Located in upper right quadrant of the abdomen
Liver Functions • Metabolizes carbohydrates: converts between glycogen and glucose • Metabolizes lipids: • Converts carbohydrates and proteins into fat molecules • Sends fats to adipose tissue for storage • Metabolizes protein
Liver Functions, continued….. 4. Storage of: glycogen, iron, vitamins A, D, and B12 5. Blood filtering: removes damaged RBC’s and foreign substances 6. Detoxification: removes toxins from blood 7. Secretes bile
Hepatitis • Inflammation of the liver • Viral types: • Hepatitis A: • Short-lived; spread by feces-contaminated food or objects (daycares) • Hepatitis B: spread by infected body fluids • Hepatitis C: • About half of all cases of hepatitis • Spread through infected blood • Hepatitis D-G
Gallbladder • Pear-shaped sac on the liver’s inferior surface • Stores and releases bile into the small intestine • Gallstones are formed when cholesterol in bile precipitates and crystallizes.
Function of Bile • Bile salts aid digestive enzymes: • Breaks fat globules into smaller pieces so lipases can digest them more easily. • Enhances absorption of fatty acids, cholesterol, and vitamins A, D, E, and K.
Small Intestine • Functions: • Receives secretions from what two organs? • Completes digestion of nutrients in chyme • Absorbs products of digestion • Transports residues to large intestine
Parts of the Small Intestine • Duodenum • C-shaped • Curves around pancreas • The most fixed portion of small intestine • Jejunum • Ileum
Large Intestine • Separated from small intestine by the Ileocecal sphincter • Larger in diameter than the small intestine • Absorbs water and electrolytes from remaining chyme • Forms and stores feces
Parts of the Large Intestine • Cecum • Appendix hangs down from the cecum • No digestive function • Contains lymphatic tissue • Colon: ascending, transverse, descending, and sigmoid (s-shaped) portions • Rectum – lies next to the sacrum • Anal canal and anus
Nutrients & Nutrition • Using your textbook and the internet, complete the “Nutrients & Nutrition” chart handout.
From the 4 days of eating that you have recorded, choose the day you think your diet was nutritionally the best, and the day that most closely resembles a "typical" day for you. Examine the diets of these 2 days and compare them to the nutritional requirements you researched over the past 2 days. Answer the following questions: 1. Is your "typical" diet nutritionally sound? Was your “best” day really any better? If yes, how? 2. In what nutrients would you most likely be deficient? How could you fix that? 3. Based on your analysis, what foods do you need to eat more of, and what foods do you need to cut back on? WHY?
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