Metabolism

basal metabolic rate regulation of body temperature obesity BMI

1. M E T A B O L I S M

2. Metabolism is all chemical reactions in the
living cells of the body .
It is composed of :
A- Anabolism
B-Catabolism

3. Anabolism : larger substances are formed
from smaller ones
Energy consuming
eg .. Formation of proteins from amino acids

4. Catabolism : breakdown of larger
molecules into smaller ones with liberation
of energy
eg .. Breakdown of starch into glucose

5. Energy is used in :
1-WORK: Chemical , Osmotic ,electric
Mechanical
2- Body Temp
3- Secretions
4-Active Reabsorption
5- Storage : ATP

6. Breakdown
Proteins to Amino Acids, Starch to Glucose
Synthesis
Amino Acids to Proteins, Glucose to Starch
Metabolism : all chemical reactions in the body
1-WORK:
Chemical ,
Osmotic ,electric
Mechanical
2- Body Temp
3- Secretions
4-Active
Reabsorption
5- Stored : ATP

7. The calorie
is the unit used to measure the amount of energy
intake(potential energy of food) and energy output
Energy needed to heat 1gm water – 1 C
From 15 to 16 C

8. ESTIMATION OF ENERGY
INTAKE (heat value of the food )
Physiological heat value :
The amount of heat liberated from oxidation
of 1 gm of certain food INSIDE the body.
1
Physical heat value :
The amount of heat liberated from the
oxidation of 1 gm of certain food
OUTSIDE the body.
1

10. FOOD TYPE PHYSICAL
HEAT
PHSIOLOGICAL
HEAT
1 gm CHO 4.1 calorie 4.1 calorie ( 4 )
1 gm fat 9.3 calorie 9.3 calorie ( 9 )
1 gm PTN 5.3 calorie 4.1 calorie ( 4 )
N.B. : PTN
N.B. : Absorption
N.B : O
2
Heat value

11. N.B :
The physiological heat value of protein is less than
the physical heat value because proteins contain
16 nitrogen atoms which if completely oxidized
in body would produce nitric acid in exess
amounts which leads to marked acidosis
So compete oxidation does not occur and urea is
excreted in urine taking with it part of energy of
proteins ..

12. Respiratory Quotient
It is the ratio between volume of CO2
liberated and volume of O2 consumed at
the same period of time .

13. R.Q.
CHO :
C6H12O6 + 6 O2 -- 6 CO2 + 6 H2O + E
R.Q = 6/6 = 1
FATs : R.Q = 18/26 = 0.7
Protein : R.Q = 0.8
Mixed food : R.Q = 0.85

14. 1- Carbohydrates : 1 2- Fats : 0.7
3- Proteins : 0.8 MIXED = 0.85

15. Significance of R.Q.
1- Determination of the nature of the food
substance oxidized :
CHO :
C6H12O6 + 6 O2 -- 6 CO2 + 6 H2O + E
R.Q = 6/6 = 1
FATs : R.Q = 18/26 = 0.7

16. Significance of R.Q.
2- Transformation of one food substance to
another .
CHO to fat ( lipogenesis ) ++ RQ ( above 1 )
Fat to CHO ( gluconeogenesis ) - - RQ
3- Calculation of BMR by determination of O2 heat
value .
1- Carbohydrates : 1 2- Fats : 0.7
3- Proteins : 0.8 MIXED = 0.85

17. Factors affecting RQ
+ + R Q - - R Q
1- Lipogenesis.
2- Exercise.
3- Acidosis .
4- Fever .
1- Gluconeogenesis
2- Recovery from
exercise.
3- Alkalosis.
4- D.M. & starvation
( + fat metabolism ).

18. The excess R Q
A – a
Excess RQ =
B – b
Significance of Excess RQ :
1- Duration of the exercise
2- Determination of the fuel used during the
execise .
Factors affecting the excess RQ :
1- Duration of exercise 2- Nature of fuel used

19. The metabolic rate ( MR )
The rate of energy expenditure ( production ) in specific period of time

20. Measurment of metabolic rate
Direct calorimetry
Indirect Calorimetry

21. Direct calorimetry
It measures the body heat loss :
a. Conduction& convection & radiation = A
b. Evaporation = B
A : Volume of water X Temp. difference X sp
B : 1 CC of water evaporated = 0.58 Cal
MR = A + B

25. Indirect Calorimetry
M R = O2 consumption/ hour X O2 heat value.
M R = O2 consumption/ hour X 4.8.
O2 heat value = Energy equivalent of O2 :
Is amount of heat in calories produced when 1 liter of
O2 is used to oxidize food substances
CHO 5 c
Fat 4.7 c
Ptn 4.5
Mixed diet 4.8 ( R Q is 0.85 ) for mixed diet .

26. Indirect Calorimetry
M R = O2 consumption/ hour X O2 heat value.
M R = O2 consumption/ hour X 4.8.
Methodes of estimation of O2 consumption :
1- Closed methode.
2- Open methode .

30. BASAL METABLOIC RATE( BMR (
The energy expenditure /square meter
surface area / hour measured under basal
conditions :
1- Complete mental & physical rest.lying in
bed for 1\2 hour before experiment ( not
sleep )
2- Comfortable temperature .20-25
dressed , 28-31 naked .
3-Post absorptive state ( 12-14 hours after
meal )

31. Basal Metabolic RateBasal Metabolic Rate
It is the unavoidable energy cost of living
ie energy needed for metabolic activities of
the heart , lungs , brain etc …

32. Importance of BMRImportance of BMR
11. . Generating & maintaining ionic gradients Generating & maintaining ionic gradients
and other molecules across membranesand other molecules across membranes..
22. . The mechanical work of respirationThe mechanical work of respiration..
33. . Circulation of bloodCirculation of blood..
44. . Production of muscle tone, signals Production of muscle tone, signals
conduction in nervous systemconduction in nervous system..
55. . Obligate heat loss via body surfaces to Obligate heat loss via body surfaces to
the environmentthe environment..

33. BMR
BMR of 70 kg male is about 2000 C/ day
But is expressed per square meter of the
body / hour .
= 40C/hour/m2

34. Measurement of BMR
1- Direct :
HEAT / hour
BMR =
SA
2- Indirect :
O2 consumption / hour X 4.8
BMR =
S A

35. Normal value of BMRNormal value of BMR::
In adult man 40 C/H/M2 ± 15%In adult man 40 C/H/M2 ± 15% . .
Clinical expression of BMRClinical expression of BMR::
Expressed as a % of increase or decrease fromExpressed as a % of increase or decrease from
the normal standard value for the subjectthe normal standard value for the subject..
e.g. If BMR = 60 C/H/M2( + 20 C/H/M2e.g. If BMR = 60 C/H/M2( + 20 C/H/M2))
Exceeding the normal standard value by 20Exceeding the normal standard value by 20
so, +50% ( higher than normal valueso, +50% ( higher than normal value

36. Factors affecting BMR
a-physiological
1- Age :
Newly born : 25 Cal /hour/m2 5yrs : 60
Puberty : 55 20 years : 40.
After 20 decrease by 1 Cal every 10 years .
2- Sex. Females are lower by 7 %
3- Athletes. Higher by 10 %
4- Climate. Higher in cold by 10 %
5- Race : East -- Lower .
6- Diet : PTN. Increase by 10 %
7- Sleep. Decrease by 10 %
8 - Pregnancy. Increases until double at end of pregnancy

37. b-Pathological factors
Increased BMR Decreased BMR
1- Hyperthyroidism
2-Hyperpituitarism
3- Hyperfunction of
Adrenal cortex.
4- Hyperthermia.(fever)
5- Heart failure.
6- Anemia.
7- diabetes
1- Hypothyroidism.
2- Hypopituitarism
3- Hypofuction of
Adrenal cortex.
4- Hypothermia.
5- Under nutrition.

38. C-Chemical factors
Factors increase BMRFactors decrease BMR
Thyroxin Propyl thyrocil
adrenaline Excess iodine
Amphetamine

39. Step 2 :

Normal BMR is 40 Cal /h / m
2
Example : O2 consumption is 5000 ml /10 min …height 170 cm
Weight is 70 kg

Then calculate the percentage : BMR / normal X 100

40. Calculate the MR
O2 consumption in 6 minutes = 1470 ml
Body surface area 1.6 m2

41. Calculate the BMR
O2 consumption in 12 minutes = 6.3 L
Height 165 cm
Weight 75 kg

42. Calculate the BMR
O2 consumption in 6 minutes = 900 ml
Height 150 cm
Weight 75 kg

43. The Specific Dynamic (SPA)
The power of food to stimulate the metabolic rate
(obligatory energy production during assimilation
of the food in the body ).
Factors affecting :
1- Type of food : amount needed to provide body by 100
Kcal will increase the MR in case of :
PTN by 30% CHO by 6% FAT by 4%
2- Amount of food :
3- Atmospheric temperature
Cause of SPA : Different metabolic processes

44. PTN :
Deamination , Urea formation , oxidation to
CO2 and H2O .
CHO :
Metabolic reactions in liver as lipogenesis
FATs :
Alimentry lipemia and utilization of fats by
tissues .

45. Nitrogen Balance
Normal PTN content of the body is 12 KG
Nitrogen balance means that the nitrogen intake equals
nitrogen output ( loss) .
+ve nitrogen balance : the intake exceeds loss in growth.
( anabolic hormones : physiological doses of thyroid
hormones , Testosterone , growth hormone )
-ve nitrogen balance : the loss exceeds the intake ,
Starvation ( Catabolic hormones : Glucocorticoids exess
thyroid hormones . )

46. 27
F O O D I N T A K E

47. Food intake is controlled by a specific centre in the
hypothalamus ( the Appestat ) and the limbic
system(amygdaloid nuclei ) .
The hypothalamic appestat is formed of :
Feeding centre Satiety centre
Site
Stimulus
Effect
Destruction
Lat. Hypoth.
Hypoglycemia
++ food intake
Loss of appetite
(anorexia)
Ventromed Hypoth.
++ glucose
- -food intake
Hyperphagia

48. Normally , the feeding
centre is continuously
active , only is
inactivated when
satiety centre is
activated

+ Intake - - intake
Neuropeptide Y.
Gherlin
MCH
Endorphins
Cortisol
Leptin
CRH
MSH
Cocaine
Amphetamine
Sertonin
Gherlin : is a neuropetide secreted from the hypothalamus ,
stimulates feeding centre
Leptin : Hormone – like substance secreted from adipose tissue - - appetite
There is a set point for the normal body weight

49. Ghrelin Leptin
A 28 amino acid peptide
formed by
hypothalamus and fundus of
stomach
Sereted in response to fasting .
Actions :
++ secretion of GH .
Stimulate feeding center
Stimulate gastric emptying
A hormone secreted by
adipose tissue
Amount secreted is
proportionate to amount of
body fat
Act on hypothalamus
decreasing appetite and food
intake
Leptin decreases neuropeptide
Y
And increases MSH .

50. The hypothalamic Appestst is affected by input
stimuli from :

1- Buccal and pharyngeal receptors .
2- Distension of the stomch.
3- Thermoreceptors .
4- Chemical stimuli :
Glucose :
Hyperglycemia ++ satiety centre.
Hypoglycemia ++ feeding centre
Hormones :
CCK -- appetite Glucagon ++ appetite
Drugs : amphetamine -- appetite.
Psychological factors Envirnemental and cultural .

51. Obesity
Deposition of excessive amounts of fat in
the body : +ve energy balance .
Restting of the hypothalamus.
Normally , The body fat in M: 12-18 % -
F:18-24 %
Obesity is > M: 20 % F:25% Fat

52. HOW TO MEASURE OBESITY
1- Body mass index :
Weight in KG / square height in meters.
>18.5 Underweight
18.5-25 Normal
25-30 Overweight
>30 Obesity
>40 Morbid obesity
2- Waist line. M : 80cm F: 88cm
3- Thickness of skin fold.

56. Bio-impedance
Bioelectrical impedance analysis (BIA) is a
commonly used method for estimating body
composition, and in particular body fat. Since the
advent of the first commercially available devices
in the mid-1980s the method has become popular
owing to its ease of use, portability of the
equipment and its relatively low cost compared to
some of the other methods of body composition
analysis. It is familiar in the consumer market as a
simple instrument for estimating body fat.

57. Bio-impedance cont…
•actually determines the electrical
impedance, or opposition to the flow of an
electric current through body tissues which
can then be used to calculate an estimate
of total body water(TBW). TBW can be
used to estimate fat-free body mass and,
by difference with body weight, body fat.

59. CAUSES OF OBESITY
1- Psychological causes.
2- Hypothalamic .
3- Genetic causes .
TYPES OF OBESITY :
Hypertrophic obesity .++ increased fat inside the cells.
Hypertrophic hyperplastic . ++ increased fat content and
number of cells.
TREATMENT OF OBESITY :
Decrease energy input and Increase energy output
DRUGS and sometimes surgery .

60. Complications of obesity
1- Accelerated atherosclerosis
2- GB stones
3- Osteoarthritis
4- DM
5- HTN
6-psycological .

61. 14
ECERCISE

62. ATP
- The main
source of
energy in
muscle
contraction

63. ATP sources
1- Creatine phosphate (CP(
(Phosphagen system( :
Sufficient only for 8-10 seconds
Muscle cells contain creatine phosphate
more than ATP
ATP & creatine phosphate are called
Phosphagen system

64. Glucose – lactic acid energy
system
Anerobic .
Sufficient only for 1.4 – 1.6 minutes
Anerobic oxidation of glucose
Glycogen>>Glucose >> 2 pyruvic acid + 3 ATP
pyruvic acid >> reduced to Lactic acid
Lactic acid Limits this source of energy

65. Aerobic energy system
Aerobic
Unlimited source of ENERGY
Pyruvic acid enters MITOCHONDRIA and
reacts with O2
Pyruvic acid >> H2O + CO2 + 36 ATP

66. Oxygen dept
It is the difference between O2 needed for
exercise and O2 available .
In severe muscle exercise despite
tachycardia , hyperventelation and VD
Yet no enough O2
Anerobic oxidation of glucose into lactic acid
occurs
Lactic acid accumulates inside muscle
causing fatigue

67. After exercise
O2 is needed to :
1- resynthesize ATP and Creatine
phosphate .
2- Oxidize accumulated lactic acid .
This is O2 dept .
Exess post exercise O2
consumption

69. Measurement of O2 dept
O2 dept = O2 consumption during
recovery period – O2 consumption during a
similar period of rest .

70. Causes of O2 dept
1-Accumulation of lactic acid
2-Exhausion of energy sources(ATP and
CP(

71. Significance of O2 dept
O2 dept allowes the muscle
to do severe exercise for
short periods even in O2 lack
(hypoxia ( .

72. SECOND WIND
During prolonged severe muscle exercise . The
athelete passes into 2 stages :
1- Initial Dyspnea :
Relative O2 lack , lactic acid accumulation
CO2 accumulation ( dyspnea).
Lactic acid reacts with alkali reserve
Lactic acid + NaHCO3 >> Na lactate +CO2 + H2O
CO2 produced stimulate RC causing dypnea .

73. 2- Stage of relief ( second
wind ) the steady state :
washing of excess CO2 & supply of enough
O2 keep rate of formation and removal of
lactic acid equal
Person feels comfortable and respiration
become easier .
Can be reached rapidly by training .

74. THERMOREGULATION

75. Classification
1- Homeothermic warm blood animals :
2- Poikilothermic : cold blood animals
Physiological variation.
•Circadian (diurnal) rhythm. (lowest in the morning,
highest in the afternoon).
•Age (children is 0.5
o
C more than adult). preterm ???
•Sex.(male s higher, female menstrual themogenesis
1-2 days postovulatory)
•Emotions, exercise.
•Prolonged recumbancy, starvation.

76. Regulation of Body Temperature

77. •Normal body temperature is 37
o
C± 0.6.
•41
o
C >>>> convulsions.
•43
o
C >>>> protein denaturation.
-Core temperature
-Shell temperature
(skin temperature)
-Methods :
Oral , Axillary , Rectal
34
o

78. The
Thermoregulatory
system
Thermoreceptors
-External
-Internal
Thermoregulatory center
Effector
organ
system

79. Thermoregulatory center
(Hypothalamus)
Hypothalamus is adjusted at certain temperature (set point : 37
o
C)
Anterior : heat loss Posterior : Heat gain

80. , muscle tone
Autonomic impulses :
VC, VD
(somatic impulses)
(Neuro-endocrinal impulses) :
Thyroxin , Catecholamins ,
glucocorticoids
eating or
drinking (limbic
lobe impulses)
Brown fat

81. Body Reaction to Cold Exposure
And
ACTH

82. Body Reaction to Heat Exposure

83. Evaporative heat loss
(sweat secretion)
•Composition: hypotomic
solution.
•Nerve supply: sympathetic
Cholinergic fibers.
•Center: ant. Portion of
hypothalamus.
- Insensible prespiration :
respiration

84. Fever
Increase in core body temperature above 37.6
o
C.
leukocytes
Pyrogens
hypothalamus
PGs
37
39
Aspirin
(-)

85. Treatment of fever :
1- Treatment of the cause .
2- Rapid cooling of the body by cold fomets
3- Aspirin ( antipyretic ).
4- Fluids ( oral , IV ) .
Benefits of Fever :
1- Decrease the growth of some bacteria .
2- Increase antibody production.
3- Decrease tumor growth .
Dangers of Fever :
Brain damage ( 41 ) death occurs ( 42 )

86. Heat stroke (Sun stroke)
•Exposure to heat in humid
air >>>> max sweating
but still can’t lose all heat.
with depression of hypoth.
center >>stop sweating >>
marked elevation of body
temp. and symptoms.
(dizziness, vomiting, coma,
Dehydration & electrolyte loss.
hyperpyrexia>>> brain damage.
Fatal unless treated.

87. Hypothermia
•Decrease in core body temperature below
normal.
•Slow down of metabolism physiological
processes.
•↓HR,↓ RR, ↓BP.
•21-24
o
C >>>> reversible by gradual warming.
•If more severe >>>> cell freezing.
•TTT: VERY GRADUAL warming (rethawing)
otherwise >>>> cell destruction & death.

88. Types of sweat glands :
-Eccrine : The cells are not destroyed during
secretion
-Apocrine :Cells are destroyed ( axilla , groin )
MINERS DISEASE :
Workers in mines are exposed to very high
external temperature ( excessive sweating ) :
Dehydration , Nacl loss.

89. STARVATION
It is Complete absence of food intake . The body
depends on its food reserves.
Symptoms :
1- decreased circulatory and respiratory functions :
HR , ABP , Vital Capacity.
2- Hunger pains.
3- Mental depression. Fainting attacks
4- Muscular weakness.
5- Decreased BMR and glandular activity.
6- Loss of body weight : Muscles ,water, fat .

90. Metabolic effects of starvation
1- General metabolism :
BMR is decreased to about – 30 % .
Temp decrease by 0.1 to 1 C .
R Q decrease to 0.7 when fat is the main source
of energy as CHO are used up .

91. 2- Carbohydrate metabolism :
Glycogen stores are depleted in the first 24
hours .
But glucose level is still maintained at its
fasting level 70 mg % due to
gluconeogenesis .

92. 3- Fat metabolism : ( becomes the main
source of energy )
Neutral fat >> Glycerol + FFA >>>
CO2+H2O + energy
or ketons ( ketosis )

93. 4- Protein Metabolism :
a- Gluconeogenesis : formation of glucose .

b-Formation of : HB ,Plasma ptns ,
enzymes .

c- Prevent ketosis as it prevent exess fat
metabolism .

94. Protein metabolism passes into the
following 3 stages in starvation :
1- Adjustment (4 – 5 days ): according to the
PTN content in diet before starvation
2- Steady stage : amount of N2 in urine is
constant in all persons 10 gm/ day .
3- Premortal stage : excessive N2 loss
( destruction ) death followes (feeling sad )

95. BLOOD CHANGES
1- Blood glucose : fasting ( 70 mg% )
A.A. : fasting ( 5-7 mg %
Blood lipids ++ ( lipaemia ). Mobilizatiation
of stored fat .
2- Alkali reserve : decreased (to buffer
ketoacids )
3- Blood vloume , HB ,RBCs : all decresed
4- Plasma ptns : decreased >> edema
5- Minerals Na , K , Ca , PO4 : constant

96. URINE CHANGES
1- Urine volume and specific gravity : depends on
water intake.
2- N2 : depends on stage of starvation .
3- Uric acid : decreased to half.
4- Creatinuria : ++ ptn breakdown
5- NH3 : ++ due to acidosis .
6- Minerals :
Na, K : decrease and disappear from urine .
Ca , PO4 : increased derived from bone
Phosphorus , sulpher +++ then ---- derived from
soft tissue .