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THE BASAL METABOLIC
RATE
D. C. MIKULECKY
PROFESSOR OF PHYSIOLOGY
VIRGINIA COMMONWEALTH
UNIVERSITY
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” (THE
MINIMAL WAKING RATE OF
INTERNAL ENERGY EXPENDITURE)
DIRECT CALORIMETERY(MEASURE
RATE OF HEAT PRODUCTION)
INDIRECT CALORIMETERY
(MEASURE OXYGEN CONSUMPTION)
(SEE LAB NOTES FROM DEC.2)
FACTORS WHICH INFLUENCE
BMR
FOOD INTAKE
THYROID HOMONE
EVEN LOWER LEVELS DURING SLEEP
(10-15%)
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 WITH
RESPECT TO THE BODY
INPUT - OUTPUT = STORAGE OR DEPLETION
(CONTINUITY EQUATION
(
E/t = 2E)
)
OUTPUT = INTERNAL WORK + EXTERNAL WORK
INTERNAL WORK ------> HEAT
STORAGE AND/OR
DEPLETION
NEUTRAL 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 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
EFFICIENCY OF
METABOLISM
50% GOES TO ATP
50% GOES TO HEAT
FOOD INTAKE
CONTROLED BY HYPOTHALAMUS
FEEDING CENTERS
SATIETY CENTERS
CONTROL OF FUEL
METABOLISM
GLYCOGENESIS
GLYCOGENOLYSIS
GLUCONEOGENESIS
PROTEIN SYNTHESIS
PROTEIN DEGRADATION
FAT SYNTHESIS
FAT BREAKDOWN
ANABOLISM VS CATABOLISM
BUILD UP VS BREAKDOWN OF
LARGE MOLECULES
ANABOLISM REQUIRES ENERGY
(ATP)
CATABOLISM:ENERGY PRODUCTION
BLOOD GLUCOSE
ONE GRAM YIELDS ABOUT 4 CALORIES
70 KG PERSON 2,000 CALORIES/DAY
NEED 500G GLUCOSE
AS AN ISOTONIC SOLUTION THAT WOULD
BE ABOUT 10L
THE ACTUAL AMOUNT IS ABOUT 20G OR
ENOUGH FOR 1 HOUR
PANCREATIC HORMONES
AND BLOOD GLUCOSE
INSULIN
GLUCAGON
INSULIN: ACTION ON BLOOD
SUGAR
BETA CELLS IN ISLETS OF
LANGERHANS: INSULIN
FACILITIES GLUCOSE ENTRY INTO
CELLS
STIMULATES GLYCOGENESIS
INHIBITS GLYCOGENOLYSIS
INHIBITS GLUCONEOGENESIS
INSULIN: ACTION ON FAT
INCREASES TRANSPORT INTO
ADIPOSE CELLS
PROMTES TRIGLYCERIDE
SYNTHESIS
INHIBITS LIPOLYSIS
INSULIN: ACTION ON
PROTEIN
PROMOTES UPTAKE OF AA BY
MUSCLE AND OTHER TISSUE
PROMOTES PROTEIN SYNTHESIS
INHIBITS PROTEIN DEGRADATION
CONTROL OF INSULIN
SECRETION
NEGATIVE FEEDBACK: BLOOD
SUGAR
BLOOD AA
GI HORMONES
PARASYMPATHETIC ACTIVITY
TWO TYPES OF DIABETES
MELLITUS
TYPE I: AUTOIMMUNE
DESTRUCTION OF BETA CELLS, LACK
OF INSULIN SECRETION
TYPE II: REDUCED SENSITIVITY OF
INSULIN RECEPTORS
ACUTE EFFECTS OF DIABETES
MELLITUS












EXTRACELLULAR GLUCOSE EXCESS
GLUCOSE IN URINE
EXCESS FLUID LOSS
CIRCULATORY FAILURE
RENAL FAILURE
NERVOUS SYSTEM MALFUNCTION DUE TO DEHYDRATION
EXCESSIVE FOOD INTAKE
PROGRESSIVE WEIGHT LOSS
MOBILIZTION OF FAT
KETOSIS
ACIDOSIS
COMA AND DEATH
GLUCAGON
PANCREATIC ALPHA CELLS
GENERALLY OPPOSES ACTIONS OF
INSULIN
DECREASE GLYCOGEN SYNTHESIS
PROMOTE GLYCOGENOLYSIS
STIMULATE GLUCONEOGENESIS
PROMOTES FAT BREAKDOWN
ONLY IN LIVER: PROTEIN CATABOLISM
EPINEPHRINE, CORTISOL, AND
GROWTH HORMONE
ALL INCREASE BLOOD GLUCOSE AND
FATTY ACIDS
CORTISOL INCREASES BLOOD AA
AND DECREASES MUSCLE PROTEIN
GH DECREASES BLOOD AA AND
INCREASES MUSCLE PROTEIN
OVERALL REGULATION OF
BLOOD GLUCOSE
(+)
RELEASE
FROM LIVER
-
( )
BLOOD
GLUCOSE
INSULIN
(+)
EPINEPHRINE
AND
NOREPINEPHRIN
(+)
GLUCAGON
(+)
GLUCOCORTICOIDS
-
( )
-
( )
CONSUMPTION
BY
MUSCLE AND FAT CELLS
GH