1. Nutrition/Metabolism/Digestion

2. Nutrition
Process by which food is taken into the body and changed into a form that can be utilized by cells

3. Nutrients
Food substances that the body uses for normal growth, maintenance, and repair
Bulk of organic nutrients used as fuel to produce ATP (energy)
Energy values of foods measured in units called kilocalories (kcal)

4. Nutrients (cont’d) Most, but not all are ingested Major nutrients
Some synthesized in cells
Major nutrients
Make up bulk of what we eat
Carbohydrates, proteins, lipids
Vitamins and minerals– minute amounts
Water

5. Nutrients (cont’d) Essential nutrients
Cannot be synthesized by body cells
Must be ingested in the diet

6. Carbohydrates Composed of simple sugar subunits
Primary source of energy
Monosaccharides – can be absorbed into bloodstream
Glucose

7. Carbohydrates (cont’d)
Disaccharides
Polysaccharides – complex carbohydrates
Starch
Glycogen
Cellulose (cannot be digested) = fiber

8. Carbohydrates (cont’d)
Obtained primarily from plant products
Starches
Vegetables, seeds, grains, and nuts
Simple sugars
Fruits and candy
Glycogen
Meat
Too little = loss of weight
Too much = obesity

9. Carbohydrates (cont’d)
Minimum of 100 grams/day
grams/day is recommended
Concentrate on complex carbohydrates
55% of total calories
4 calories/gram

10. Proteins Made up of amino acids Body can only make 12 of 20
Structural building blocks of body
Body can only make 12 of 20
To obtain the other 8 (essential amino acids) one must eat animal sources (complete proteins)
meat
milk
cheese
eggs

11. Proteins (cont’d)
Incomplete proteins (low in one or more essential amino acids)
Legumes
Nuts
Seeds
Must be combined
.8 grams/ kg of body weight
4 calories/gram
Too little = weight loss & tissue wasting, anemia & edema
Too much = obesity

12. Lipids Help body absorb fat soluble vitamins
Triglycerides - neutral fats
Most abundant form of dietary fat
Provide reserve energy, cushion body organs, insulates
Phospholipids
Synthesize plasma membranes and myelin

13. Lipids (cont’d) Cholesterol Not used for stored energy
Plasma membranes
Structural basis of vit. D, steroid hormones, and bile salts

14. Lipids (cont’d) Saturated fats Unsaturated fats Solid
Animal products – meat, dairy
Some plants - coconut
Unsaturated fats
Liquid
Seeds, nuts, veg. oil

15. Lipids (cont’d) Cholesterol
Egg yolks, meat, milk products
Linoleic and linolenic acids – essential fatty acids
Body cannot synthesize
Must be ingested

16. Lipids (cont’d) Less than 30% of total intake
Replace sat. fats with unsaturated
250 mg or less of cholesterol
Too little = loss of wt.; rapid loss of heat
Too much = obesity
9 calories/gram

17. Vitamins
Organic compound required in small amounts for growth and health
Coenzymes - assist enzymes in the regulation of physiological processes

18. Vitamins (cont’d) Most are not made in the body
Must be taken in via foods or vitamin supplements
Exceptions
D – made in skin
B and K - made by intestinal bacteria
Beta carotene – converted to A

19. Vitamins (cont’d) Water-soluble
Absorbed along with water across the intestinal wall
B-complex vitamins & Vit. C
Exception – B12 – must bind to intrinsic factor to be absorbed
Not stored in large amounts in the body
Excreted in urine if not needed
Damaged during food processing and cooking

20. Vitamins (cont’d) Fat-soluble
Bind to fats and are absorbed along with the fat products of digestion
Vit A, D, E, and K
Except for K, stored in body
Can have vitamin toxicity, especially vitamin A
Not easily damaged by cooking and food processing

21. Vitamins (cont’d) Antioxidants A,C, & E
Disarm tissue-damaging free radicals and have anticancer effects

22. Minerals Inorganic molecules
Make up about 4% of body by weight (most in bones and teeth)
Most important
Ca & P
But K, S, Na, Cl, Mg also essential
Mineral-rich foods: vegetables, legumes, milk, some meats

23. Minerals (cont’d)
Incorporated into structures that need reinforcement for strength
Work with other nutrients to ensure a smoothly functioning body
Fine balance between uptake and excretion important
Retain needed amounts while preventing toxic overload

24. Metabolism

25. Metabolism All chemical reactions necessary to maintain life Anabolism
Reactions in which larger molecules or structures are built from smaller ones
Energy required
Catabolism
Processes that break down complex structures to simpler ones
Energy released and captured to make ATP

26. Carbohydrate Metabolism
As glucose is oxidized, CO2, water, and 36 ATP are formed
Cellular respiration
Hyperglycemia – excessively high levels of glucose in blood
Some of excess stored as glycogen or converted to fat
Hypoglycemia – blood glucose levels too low
Liver breaks down glycogen and releases glucose to the blood

27. Lipid Metabolism Provide reserve energy
When carbohydrates are not available, more fats are oxidized to produce ATP
Excessive fat breakdown causes blood to become acidic.
Excess dietary fat stored in subcutaneous tissue and other fat deposits

28. Protein Metabolism Amino acids most important anabolic nutrients
Form all protein structure and the bulk of the body’s functional molecules
Amino acids are actively taken up from the blood by tissue cells
Once absorbed into cells, may be used to synthesize needed proteins, or serve as a secondary energy source

29. Protein Metabolism (cont’d)
Amino acids are oxidized to form ATP mainly when other fuel is not available
Ammonia, released as amino acids are catabolized, is detoxified by liver cells that combine it with CO2 to form urea

30. Role of Liver in Metabolism
The body’s main metabolic organ
Plays a crucial role in processing (or storing) virtually every nutrient group.
Maintains homeostasis of blood glucose levels
Degrades hormones
Detoxifies drugs and alcohol
Synthesizes plasma proteins

31. Role of Liver in Metabolism (cont’d)
Forms nonessential amino acids and converts ammonia to urea
Packages fatty acids into forms that can be stored or transported
Stores certain vitamins
Conserves iron salvaged from worn-out RBC
Makes cholesterol and secretes cholesterol’s breakdown products in bile

32. Lipoproteins
Fats and cholesterol are transported in the blood by lipoproteins
High-density lipoproteins (HDLs)
Transport fats from tissues throughout the body to the liver
Broken down to become part of bile
Energy is used to power cellular activities
“Good cholesterol”
Levels okay; above 60 – thought to protect against heart disease

33. Lipoproteins (cont’d)
Low-density lipoproteins (LDLs)
Transport cholesterol from liver to tissues
“Bad cholesterol”
High levels – 160 or above
Very low-density lipoproteins (VLDLs)
Converted to LDLs in liver

34. Body Energy Balance

35. Body Energy Balance
Energy intake = total energy output (heat + work + energy storage)
When balanced, weight remains stable
When not, weight is either lost or gained

36. Regulation of Food Intake
Factors thought to be involved in regulating eating behavior:
Rising and falling levels of nutrients
Hormones
Body temperature
Psychological factors

37. Metabolic Rate
Three major food nutrients yield different amounts of energy:
Carbohydrates and proteins: 4 kcal/g
Fats: 9 kcal/g

38. Metabolic Rate (cont’d)
Basal Metabolic Rate (BMR)
Total amount of energy used by the body when one is in a basal state (at rest)
Energy needed to just perform essential life activities
Factors influencing BMR:
Surface area, age, gender, stress, hormones
Thyroxine – metabolic hormone

39. Metabolic Rate (cont’d)
Total Metabolic Rate (TMR)
Number of calories used by the body to accomplish all ongoing daily activities
Increases greatly as muscle activity increases
When TMR = total calorie intake, weight remains constant

40. Regulation of Body Temperature
Body temperature - balance between heat production and heat loss
Normally 35.60C to 37.80C
As food is catabolized to form ATP, more than 60% of energy released escapes as heat, warming the body

41. Regulation of Body Temperature (cont’d)
Hypothalamus initiates the following, as necessary, to maintain body temperature within normal limits:
Heat-loss processes:
Radiation of heat from skin and evaporation of sweat or
Heat-promoting processes:
Vasoconstriction of skin blood vessels and shivering

42. Regulation of Body Temperature (cont’d)
Fever (controlled hyperthermia) represents body temperature regulated at higher than normal levels

43. Weight Gain and Loss

44. Weight Loss 1. Determine you resting metabolic rate (Weight X 10)
2. Determine calories needed for activities
Bicycling 10 mph 2.7 cal/lb/hr
Dancing 2.6 cal/lb/hr
Jogging 6 mph 4.2 cal/lb/hr
Walking 3.5 mph 2.4 cal/lb/hr
Weight training 1.9 cal/lb/hr

45. Weight Loss 3. Determine calories for normal activities.
Sedentary add %RMR
Moderately active add %RMR
Very active add %RMR
4. Add 1, 2, & 3 together
5. Subtract 20% of total calories needed

46. Weight Gain Same as weight loss, but add 20% 60-70% Carbohydrate
10-15% Proteins
Rest = Lipids