NUTRITION, ENERGY BALANCE AND TEMPERATURE REGULATION
D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY
ANDFACULTY MENTORING PROGRAM
ENERGY
• THE CAPACITY TO DO WORK
• THE CALORIE IS THE AMMOUNT OF HEAT ENERGY NECESSARY TO RAISE THE TEMPERATURE OF 1 GRAM OF WATER 1 DEGREE CENTIGRADE
• THE NUTRITIONAL CALORIE IS 1000 CALORIES OR THE KILOCALORIE
ENERGY BALANCE
INPUT - OUTPUT = STORAGE OR DEPLETION
OUTPUT = INTERNAL WORK + EXTERNAL WORK
INTERNAL WORK ------> HEAT
STORAGE AND/OR DEPLETION
• NUETRAL ENERGY BALANCE OCCURS WHEN INPUT AND OUTPUT MATCH
• POSITIVE ENERGY BALANCE OCCURS WHEN INTAKE EXCEEDS OUTPUT - ENERGY IS STORED AS GLYCOGEN OR FAT
• NEGATIVE ENERGY BALANCE OCCURS WHEN OUTPUT EXCEEDS INTAKE- ENERGY STORES ARE DEPLETED
FOOD AS STORED FUEL
• 3500 CALORIES = 1 LB OF BODY MASS
ENERGY INPUT
• 50% GOES TO ATP
• 50% GOES TO HEAT
• CARBOHYDRATE, FAT AND PROTEIN
THE METABOLIC RATE
METABOLIC RATE = ENERGY EXPENDITURE PER UNIT TIME
(Calories/hour)
FACTORS INFLUENCING METABOLIC RATE
• EXERCISE
• FOOD INTAKE
• SHIVERING
• ANXIETY
BASAL METABOLIC RATE
• BODY’S “IDLING SPEED”
• DIRECT CALORIMETERY
• INDIRECT CALORIMETERY
CONTROL OF FOOD INTAKE
• POORLY UNDERSTOOD• OBESITY IS TOO MUCH STORED FAT• LIPOSTATIC THEORY• GI DISTENSION THEORY• GLUCOSTATIC THEORY• ISCHYMETRIC THEORY• CCK SECRETION THEORY• PSYCHOSOCIAL INFLUENCES
FOOD INTAKE
• CONTROLED BY HYPOTHALAMUS
• FEEDING CENTERS
• SATIETY CENTERS
FOOD AS FUEL
• CARBOHYDRATE 4 CAL/G
• PROTEIN 4 CAL/G
• FAT 9 CAL/GRAM
• ETHANOL 7 CAL/G
FOOD AS STORED FUEL
• 3500 CALORIES = 1 LB OF BODY MASS
ESSENTIAL AMINO ACIDS
• VALINE• THREONINE• ISOLEUCINE• LEUCINE• HISTADINE
(IN INFANTS)
• METHIONINE, • PHENYLALANINE• TRYPTOPHAN• LYSINE
PROTEIN QUALITY
• ONLY 20% OF THE RDA NEEDS TO BE COMPLETE PROTEIN (11 GRAMS FOR MALES 9 GRAMS FOR FEMALES …A LITTLE MORE THAN SUPPLIED BY A GLASS OF MILK)
• MORE DIVERSITY IS THE KEY THOUGH: 60% RDA FROM GRAIN, 35% FROM LEGUMES, 5% FROM GREEN LEAFY VEGETABLES
PLANTS AND PROTEIN QUALITY
FOOD SOURCE LIMITING AA ABUNDANT AA
WHOLE GRAINS THREONINE METHIONINE,LYSINE
CORN LYSINE,THREONINE,TRYPTOPHAN
OATS, RICE,WHITE FLOUR
LYSINE
LEGUMES SULFUR AA,TRYPTOPHAN
LYSINE,THREONINE
PLANTS AS A PROTEIN SOURCE
• 65% OF THE PER CAPITA SUPPLY WORLD WIDE
• 32% OF THE PER CAPITA SUPPLY IN THE US
PROTEIN SOURCES-EXCEPTIONS
• SOYBEANS
• QUINONA
• SPINACH
• HAVE THE SAME QUALITY AS MILK
INCOMPLETE PROTEINS NEEDED TO MEET REQUIREMENTS
• 2 2/3 CUPS COOKED WHEAT• 3 CUPS COOKED RICE• 5 3/4 SLICES BASIC BREAD• 3 CUPS DICED POTATOES• 1/3 CUP SOY SPREAD• 1/2 CUP WHEAT GERM• 2 3/4 CUPS RICE WITH 1/3 CUP COOKED
PEAS
SOME DISEASES LINKED WITH DIET
• CANCER
• HEART DISEASE
• HIGH BLOOD PRESSURE
• OBESITY
• DIVERTICULITIS
FOOD INGREDIENTS AND DISEASE
• REFINED SUGAR
• FAT
• SALT
• LOW IN FIBER
CANCER AND DIET: PHYTOCHEMICALS
• FOUND ONLY IN PLANTS
• IMMUNE FUNCTION
• HORMONE BALANCE
• DETOXIFICATION
CANCER AND DIET N.R.C.RECOMMENDATIONS
• EAT LESS FAT (30% OR LESS 0F TOTAL CALORIES)
• EAT FRUITS, VEGITABLES, AND WHOLE-GRAIN CEREAL FOODS EVERY DAY (ESPECIALLY THOSE HIGH IN VITAMINS A AND C)
• AVOID HIGH DOSE SUPPLIMENTS OF VITAMINS OR OTHER NUTRIENTS
• ALCOHOL ONLY IN MODERATION
SOME WAYS TO CUT DOWN ON FAT
• EAT MORE VEGETARIAN MEALS
• EAT MORE FRESH FRUIT OR YOGURT INSTEAD OF DESSERTS
• USE YOGURT AS DRESSING INSTEAD OF OIL
• USE FRESH HERBS INSTEAD OF BUTTER (AND INSTEAD OF SALT)
TYPES OF VEGETARIAN DIETS
• VEGAN: NO ANIMAL PRODUCTS (NEED DIETARY SUPPLIMENTS AND VARIED PROTEIN SOURCES)
• LACTO: +DAIRY PRODUCTS
• LACTO-OVO: +EGGS
FIBER
• ROUGHLY SPEAKING, EVERYTHING IN PLANT FOODS OUR DIGESTIVE ENZYMES CAN NOT BREAK DOWN
• NURTURES AEROBIC BACTERIA IN GUT• SOLUABLE FIBER REDUCES INSULIN NEED
IN DIABETICS• CHELATORS-INCREASE NEED FOR
MINERALS
TYPES OF FIBER
• PECTINS: IN CELL WALL OF FRUITS, BIND BILE SALTS
• GUMS: STICKY SUBSTANCES EXUDED BY PLANTS, LOWER CHOLESTEROL UPTAKE AND SLOW SUGAR ABSORPTION
• CELLULOSE: PLANT CELL WALLS, BULK AND TOXIN ELIMINATION
• HEMICELLULOSES: PLANT CELL WALLS, BULK
• LIGNIN: ROOT VEGETABLES, BULK
EFFECT ON MICROFLORA
• LOWER TOTAL ANAEROBIC, IN PARTICULAR, CLOSTRIDIUM
• DIET CAN ALTER THE METABOLIC ACTIVITY OF THE FLORA
• MEAT AND UNREFINED SUGAR INCREASES UNWANTED BACTERIA
• VEGETARIAN DIET LOWERS RISKS OF BOWEL CANCER
RECOMMENDED FIBER INTAKE
• 20 - 25 g/day WITH AN UPPER LIMIT OF 35 g/day
• FAMILY HISTORY OF DIET-IMPLICATED CANCER 35-40 g/day
• DIABETICS UP TO 50 g/day
SOURCES OF FIBER
• LEGUMES (ALSO PROTEIN SOURCE)
• FRUITS AND VEGETABLES
• WHOLE GRAIN CEREALS AND FLOURS
PROPOSED MECHANISMS FOR FIBER CANCER PREVENTION
• INCREASED FECAL BULK DECREASES CARCINOGEN CONCENTRATION
• CHANGE IN FLORA• SHORTENED TRANSIT TIME DECREASES
CONTACT TIME AND TIME FOR SYNTHESIS OF TOXINS
• CHANGE IN pH
CHELATORS LOWER MINERAL ABSORPTION
• PHYTATES
• OXALATES
TEMPERATURE REGULATION
• INTERNAL CORE TEMPERATURE IS 100 DEGREES F
• HEAT BALANCE RESEMBLES ENERGY BALANCE
• HEAT EXCHANGE WITH THE ENVIRONMENT
HEAT BALANCE RESEMBLES ENERGY
BALANCE
INPUT - OUTPUT = + >>RISE IN TEMPERATURE
INPUT - OUTPUT = - >>FALL IN TEMPERATURE
INPUT - OUTPUT = 0 >>NO CHANGE IN TEMPERATURE
HEAT EXCHANGE WITH THE ENVIRONMENT
• HEAT ALWAYS MOVES FROM HIGH TEMPERATURE TO LOW
• RADIATION
• CONDUCTION
• CONVECTION
• EVAPORATION
RADIATION
• THE EMISSION OF HEAT ENERGY BY ELECTROMAGNETIC RADIATION, IN THE FORM OF HEAT WAVES
CONDUCTION
• TRANSFER OF HEAT BETWEEN BODIES AT DIFFERENT TEMPERATURE IN CONTACT WITH EACH OTHER
CONVECTION
• TRANSFER OF HEAT BY AIR CURRENTS
EVAPORATION
• THE TRANSITION FROM LIQUID TO GAS USES HEAT ENERGY
• UNCONTROLLED: FROM RESPIRATORY TRACT AND SKIN SURFACE
• CONTROLLED: SWEATING
THERMOREGULATION PATHWAYS
• INPUTS TO HYPOTHALAMUS
• BEHAVIORAL RESPONSES
• SHIVERING
• VASODILATION OR CONSTRICTION OF BLOOD VESSELS IN THE SKIN
• SWEATING
INPUTS TO HYPOTHALAMUS
• FROM THE SKIN: PERIPHERAL THERMORECEPTORS
• FROM THE CORE: CENTRAL THERMORECEPTORS
BEHAVIORAL RESPONSES
• MOVE TO A MORE SUITABLE LOCATION (SHADE, INDOORS, ETC.)
• CHANGE CLOTHING
• CHANGE ACTIVITY LEVEL
SHIVERING
• RHYTHMIC, OSCILLATING SKELETAL MUSCLE CONTRACTIONS (ABOUT 10-20 PER SECOND)
• MAY INCREASE INTERNAL HEAT PRODUCTION 2-5 TIMES.
• CHEMICAL THERMOGENESIS (BROWN FAT)
VASODILATION OR CONSTRICTION OF BLOOD VESSELS IN THE SKIN
• SKIN BLOOD FLOW VARIES FROM 400 ML/MIN TO 2,500 ML/MN
• VASOCONSTRICTION OR DILATION OF THE BLOOD VESSELS IN THE SKIN IS CONTROLLED BY THE HYPOTHALAMUS
SWEATING
• CONTROLED BY SYMPATHETIC NERVOUS SYSTEM
• DEPENDS ON RELATIVE HUMIDITY OF SURROUNDING AIR
CENTRAL CONTROL
• HYPOTHALAMUS CONTROLS
• HEAT PRODUCTION
• HEAT LOSS
• HEAT CONSERVATION
• REGULATES CORE TEMPERATURE HOMEOSTATICALLY
FEVER
• FIGHTS INFECTION
• ENDOGENOUS PYROGEN FROM WBC
• LOCAL RELEASE OF PROSTAGLANDINS
• “RESETS THERMOSTAT”
• SHIVERING
• SKIN VASOCONSTRICTION