Sistem Metabolisme dan Nutrisi

8/2/2019 Sistem Metabolisme dan Nutrisi

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Metabolism and Nutrition


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Basal Metabolic Rate (BMR)

Basal Metabolic Rate is the minimal caloric requirement needed to sustain life in a restingindividual. This is the amount of energy your body would burn if you slept all day (24

hours).Factors that affect BMR:

Age: In youth, the BMR is higher; age brings less lean body mass and slows the BMR.

Height: Tall, thin people have higher BMR's.

Growth: Children and pregnant women have higher BMR's.

Body Composition: The more lean tissue, the higher the BMR. The more fat tissue, thelower the BMR.

Fever: Fevers can raise the BMR.

Stress: Stress hormones can raise the BMR.

Environmental Temperature: Both the heat and cold raise the BMR.

Fasting/Starvation: Fasting/starvation hormones lower the BMR.

Malnutrition: Malnutrition lowers the BMR.

Thyroxin: The thyroid hormone thyroxin is a key BMR regulator; the more thyroxinproduced, the higher the BMR.


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Calorimetry is the science of measuring theheat of chemical reactions or physical changes.Calorimetry involves the use of a calorimeter .

We can measure the heat or energy of variousfood by using calorimetry.

We can also measure energy expenditure from

their consumption of oxygen at different physicalactivities.
http://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Physical_changehttp://en.wikipedia.org/wiki/Calorimeterhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Calorimeterhttp://en.wikipedia.org/wiki/Physical_changehttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Science


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Bomb calorimetry to measure calorific values of food.


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Metabolic chamber to measure calorie used during physical activities


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Measurement of Basal Metabolic Rate


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Measurement of oxygen consumption


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Lipoprotein metabolism


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Calories burnt per hour of activity


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% Body Weight from Specific Tissues

Male Female

Muscle 45% 36%

Bone 15% 12%

Total FatEssential Fat (women

need more)Storage Fat

15%3%12%

27%12% (mainly forreproduction)

15%

Other Tissues 25% 25%Total 100% 100%


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Body Composition

Things that can affect these fat:body weight ratios:1. Fitness Level and Exercise --usually leads to

more lean body mass, which would increaseBMR and Energy Expenditure

2. Genetics --your body size and composition maybe predetermined by your genes

3. Age --the younger you are, the more lean body

mass4. Diet --less fat leads to less body fat

5. Gender --males, on the average, usually haveless body fat


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% Body Fat ( fat of body weight ) Ranges for Individuals:

Males Females

ExceptionallyLean

6-10%10-15% (Lower you go, more chanceof amenorrhea)

Very Lean 11-14% 16-19%

Lean 15-18% 20-25%

Moderate 19-24% 26-29%

Overfat 25%+ 30%+


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Energy expenditurebreakdown

liver 27%brain 19%

heart 7%

kidneys 10%

skeletal muscle 18%

other organs 19%

About 70% of a human's total energy expenditure is due tothe basal life processes within the organs of the body (see

table). About 20% of one's energy expediture comes fromphysical activity and another 10% from thermogenesis, ordigestion of food. All of these processes require an intake ofoxygen (usually from macronutrients like carbohydrates) and

expel carbon dioxide.
http://en.wikipedia.org/wiki/Thermogenesishttp://en.wikipedia.org/wiki/Thermogenesis


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The Harris Benedict equation for measuring

Metabolic Rate. Basal energy expenditure, BEE: the amount of

energy required to maintain the body's normal

metabolic activity, i.e. respiration, maintenance ofbody temperature etc.

Male: BEE = 66.67 + 13.75W + 5H - 6.76A

Female: BEE = 665.1 + 9.56W +1.85H -4.68A.H= height in centimeters, W= weight in kg,

A= age in years.


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Example calculation

As an example, for a 55-year-old woman,an estimated BMR might be 32 kilocalories(kcal) per square meter per hour. If her

body surface area were 1.4 m, the hourlyenergy expenditure would be 44.8 kcal/h(32 kcal/(mh) x 1.4 m). This amounts toan energy expenditure of 1075 kcal perday (44.8 kcal x 24). The value of 1075kilocalories, then, is the resting metabolicrate;


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RQ : Respiratory Quotient.

It is a measurement of ratio of oxygenconsumed to oxidise carbon in the various

food substrates.

E.g. CO2/ O2


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Glucose RQ

Because the ratio of hydrogen to oxygen atoms in allcarbohydrates is always the same as that in water that is, 2 to 1 all of the oxygen consumed by the cellsis used to oxidize the carbon in the carbohydratemolecule to form carbon dioxide. Consequently, duringthe complete oxidation of a glucose molecule, sixmolecules of carbon dioxide are produced and sixmolecules of oxygen are consumed.

The overall equation for this reaction is: C6H12O6 + 6 O2 6 CO2 + 6 H2O

Because the gas exchange in this reaction is equal, therespiratory quotientfor carbohydrate is unity or 1.0:

6 CO2 / 6 O2 = 1 RQ
http://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Oxidation


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Fats RQ

The chemical composition for fats differs from that of carbohydratesin that fats contain considerably fewer oxygen atoms in proportion toatoms of carbon and hydrogen. Fats are generally divided into sixcategories: total fats, saturated fatty acid, polyunsaturated fatty acid,monounsaturated fatty acid, dietary cholesterol, and trans fatty acid.From a basal metabolic or resting metabolic perspective, moreenergy is needed to burn a saturated fatty acid than an unsaturated

fatty acid. The fatty acid molecule is broken down and categorizedbased on the number of carbon atoms in its molecular structure

The overall equation for the substrate utilization of palmitic acid ( asaturated fat )is:

C16H32O2 + 23 O2 16 CO2 + 16 H2O

Thus the R.Q. for palmitic acid is 0.696:

16 CO(2) / 23 O2 = 0.696 RQ
http://en.wikipedia.org/wiki/Saturated_fatty_acidhttp://en.wikipedia.org/wiki/Polyunsaturated_fatty_acidhttp://en.wikipedia.org/wiki/Unsaturated_fathttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Trans_fatty_acidhttp://en.wikipedia.org/wiki/Trans_fatty_acidhttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Unsaturated_fathttp://en.wikipedia.org/wiki/Polyunsaturated_fatty_acidhttp://en.wikipedia.org/wiki/Saturated_fatty_acid


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Proteins RQ

For proteins, metabolism R.Q. is about0.8.


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Relationship between calories used, levels ofactivities and BMR


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http://www.obesityonline.org/slides/slide01.cfm?tk=34&pg=1


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http://www.obesityonline.org/slides/slide01.cfm?tk=34&pg=1


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Carbohydrates, proteins, fats, and water account for most of our nutritionalrequirements. Vitamins and minerals are required in much smaller amounts, yet

their contributions to the body's functioning are essential.


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Fourteen vitamins have been shown to be essential for normal growth andhealth in humans. Vitamins are organic molecules (i.e., moleculescontaining the elements C, H, N, or O) that are needed in trace amounts tohelp catalyze many of the biochemical reactions in the body. The term"vitamin" derives from the words "vital amine," because the first vitamins tobe discovered contained an amino group (-NR2, where R is a hydrogen orsome carbon-containing functional group) in their molecular structure.

The fourteen vitamins that we know today do not have any particularstructure in common, nor do they share a common function, but they can bedivided into fat-soluble and water-soluble molecules. In general, vitaminsdo not themselves provide chemical energy or act as biochemical buildingblocks for the body. Many vitamins (e.g., the B vitamins) assist enzymes(act as coenzymes) in activities ranging from vision to growth ability.

(Enzymes are proteins or other molecules that catalyze reactions, i.e.,

make them go faster, without themselves being permanently transformed


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Minerals are typically defined by nutritionists as inorganic (notC, H, N, or O) elements, which are used in the body to helppromote certain reactions, or form structures in the body.

Minerals are typically consumed in the form of a saltcontaining the mineral element and another ion. For example,the calcium in Cal Sium is in the form of calcium carbonate

(CaCO3).

Minerals, like vitamins, perform a wide variety of functions inthe body. Some, such as Mg2+ and Zn2+, enable enzymes tofunction, catalyzing biochemical reactions. Others, such asNa+, K+, Ca2+, and Cl-, help to maintain electrical and waterbalance in the body, transmit nerve impulses, and stimulate

muscle contraction.

Still others, such as Ca and P, form the compoundhydroxyapatite that is responsible for bone growth andstructure.


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We need about

1.5 L of water daily


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A balanced diet contains about 60% carbohydrates, 30% proteins,

10% fat plus fresh fruits and vegetables.

With this balanced diet, there is no need for further supplemental

vitamins and minerals.

Sistem Metabolisme dan Nutrisi

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