1. Nutrition and Digestion

2. Vitamin A and Learning In 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)

10. 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

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

15. Water
No set amount daily
Body must maintain normal hydration

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

17. Organisms with Intracellular Digestion

18. Organisms with Intracellular & Extracellular Digestion

19. Extracellular Digestion Fungi

20. Extracellular Digestion Most Animals

21. 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

22. Human Digestion Mechanical Digestion Chemical 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

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

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

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

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

29. Peristalsis

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

31. Structure of Stomach

32. 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

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

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

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

36. Gall Bladder
Stores bile
Releases bile into duodenum

37. 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)

38. 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

40. Hormones Control Digestive Enzymes

41. Large Intestine
Areas of Colon
Cecum
Rectum
Terminates at anus

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

43. Overweight & Obesity
Risk factors for many medical conditions

45. End chapter 27