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Nutrition and Digestion

Nutrition and Digestion. Vitamin A and Learning In The News. Nutrients. Raw materials Growth Repair Maintenance Reproduction Energy . Classes of Nutrients. Carbohydrates Lipids Proteins Minerals Vitamins Water . Macronutrients . Carbon-containing compounds

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Nutrition and Digestion

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  1. Nutrition and Digestion

  2. Vitamin A and LearningIn The News

  3. Nutrients • Raw materials • Growth • Repair • Maintenance • Reproduction • Energy

  4. Classes of Nutrients • Carbohydrates • Lipids • Proteins • Minerals • Vitamins • Water

  5. Macronutrients • Carbon-containing compounds • Energy and raw material • Includes carbohydrates, lipids, & proteins • Body needs substantial amounts

  6. Carbohydrates • Should supply 45-65% of daily energy • Includes fruits, vegetables, whole grains • more low glycemic than high glycemic

  7. Proteins • Should supply 10-35% of daily energy • Proteins made of 20 amino acids • Essential amino acids must come from diet

  8. Fats • Should supply 20-35% of daily energy • Types of fats • Monosaturated (good) • Polyunsaturated (good) • Saturated (bad) • Trans fats (bad)

  9. Vitamins • Play vital role in body function • Most are derived from diet • Required in small amounts • Excess of some can be toxic • fat soluble: vitamins A,D,E,and K • water soluble: the other nine vitamins

  10. Minerals • Inorganic substances • Transported as ions by bloodstream • Variety of uses

  11. Water • No set amount daily • Body must maintain normal hydration

  12. Digestion • Breaking of food particles into molecules • Unnecessary in autotrophs, (self feeders) • Two types of digestion • Intracellular • Extracellular

  13. Organisms with Intracellular Digestion

  14. Organisms with Intracellular & Extracellular Digestion

  15. Extracellular DigestionFungi

  16. Extracellular DigestionMost Animals

  17. Extracellular Digestion • In organisms with & without a digestive system • Fungi – no digestive system • Most animals – digestive system • Relies on enzymes (chemical digestion) • Mechanical digestion may also be present

  18. Human Digestion • Mechanical Digestion • Oral cavity by teeth • Stomach churning • Chemical digestion • Hydrochloric acid-denatures proteins, softens connective tissue, converts pepsinogen to pepsin & kills most bacteria • Bile salts emulsify lipids • Enzymes cleave chemical bonds (see table 27.3) • proteases, amylases, lipases

  19. Digestion in the Mouth • Salivary glands • Produces saliva • Mostly water • Some enzymes • Salivary amylase • Starch breakdown • Bacteria killing enzymes • mucus

  20. Digestion in the Mouth • Teeth • Mechanical digestion • Different teeth • Different functions • Fit omnivore diet

  21. Swallowing • Food is formed into a bolus • Chewed & moistened • Formed by tongue • Bolus is pushed into upper pharynx • Soft palate seals off nasopharynx

  22. Epiglottis • Folds over opening to larynx • Directs food into esophagus • Esophagus moves food toward stomach • Peristalsis = slow rhythmic squeezing • Gravity helps movement

  23. Peristalsis

  24. Stomach • Muscular sac • Churns & mixes food • Gastric glands • Produce gastric juice • Pepsinogen to pepsin • hydrochloric acid • Gastrin • Hormone • Controls gastric juices • Hydrochloric acid • Mucus-protection

  25. Structure of Stomach

  26. Food in the Stomach • Mixed with gastric juices (hydrochloric acid & pepsinogen) • Churned by muscles (3 layers of smooth muscles) • Leaves as paste (chyme) • Process takes 2-6 hours

  27. Small Intestine • Site of most digestion • Site of nutrient absorption • Area of association with accessory organs • Liver • Pancreas • Gall bladder

  28. Pancreas • Secretes many enzymes (proteases, amylase, lipase) • Empties into duodenum • Alkaline solution to help neutralize acids (sodium bicarbonate)

  29. Liver • Secretes bile (stored in gall bladder) • Components: Bile salts & bile pigments • Emulsifies fats

  30. Gall Bladder • Stores bile • Releases bile into duodenum

  31. Digestion in Small Intestine • Pancreatic amylase • Carbohydrates to maltose • Pancreatic proteases • Chymotrypsin • Trypsin • Carboxypeptidase • Pancreatic lipase • Fats • Disaccharidases (sm. Int.) • Further breaks down sugars • Peptidases (sm. intestine)

  32. Absorption in Small Intestine • Villi & microvilli Projections to increase surface area • Infoldings – increase surface area • Energy helps nutrients cross membranes • Nutrients diffuse into capillaries • Blood capillaries for all but lipids • Lacteals pick up lipids

  33. Hormones Control Digestive Enzymes

  34. Large Intestine • Areas of Colon • Cecum • Rectum • Terminates at anus

  35. Large Intestine Function • Concentration & elimination of solids • No digestive function • Absorption of water & sodium ions • Home for bacteria that produce vitamin K

  36. Overweight & Obesity • Risk factors for many medical conditions

  37. End chapter 27

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