1. Energy Balance and Temperature Regulation

2. Definition of energy metabolism
liberation
storage
transformation
utilization
liberation 2

3. Energy balance energy input =energy output

4. Energy Balance The difference between the number of kilocalories that you eat and the number of kilocalories that you burn
obesity

5. Food energy
Metabolic pool in body
External work
Internal work
Thermal energy
(heat)
Energy storage
Energy input
Energy output
First law of thermodynamics:
Energy cannot be created or destroyed, but it can be converted from one form to another

6. Source and utilization of energy
Foods (carbohydrate,fat and protein)
Heat
(>50%) O2
ATP
Muscle contraction
Nerve conduction
Active transport
Digestion
Secretion
Anabolism C
oxidation
C-P
Energy
<50%
ADP Pi
H2O,CO2
release
transport
storage
utilization

7. ATP
ATP is a combination of adenine,ribose,and three phosphate radicals.
adenine 7

9. ATP(adenosine triphosphate)
ATP:An energy “currency”
ATP is generated by combustion of carbohydrate, fat and protein .
ATP can be utilized by cell directly (high energy phosphate bonds)
Synthesis and growth
Muscular contraction
Nerve conduction
Active transport
Gland secretion

10. Phosphocreatine
Phosphocreatine: Another energy-rich phosphate compounds found in the muscle and brain
acts as an accessory depot for energy of ATP and for buffering the concentration of ATP

11. This reversible interrelation between ATP and phosphocreatine is demonstrated by the following equation: Phosphocreatine+ADP=ATP+Creatine

12. Energy expenditure

13. energy input (food) Carbohydrate (mainly glucose )
65% of the total energy (4.1kcal/g )
Glycolysis
Citric acid cycle

14. Glucose: a major energy source
Oxidation 6

15. energy input (food) Fat – fat acid (9.5kcal/g)
The storage fat in the body is much greater than that of glucose
The energy released by oxidation of fat is 2 times that produced by the same amount of glucose

16. energy input (food)
Protein: (synthesize body structure protein) 4.3kcal/g
The amount of energy provided by protein is relatively small in human being
In special situation , the protein is the main source of energy . (Hungry for a long time)

17. Factors control food intake

18. The feeding center tell us to eat, whereas
the satiety center tell us when we have had enough.

19. comparison of a normal rat
with a rat whose satiety
center has been destroyed.

20. Factors control food intake
The size of fat stores
Leptin:excellent indicator of total amount of TG store
Leptin↑+ receptor →appetite↓and metabolic rate↑
Recepter:in the ventromedial hypothalamus(satiety center)
Suppression of appetite
Responsible for the long-term matching of food intake to energy expenditure

21. Factors control food intake
The extent of glucose utilization and insulin secretion
insulin→signals satiety
The extent of glucose utilization appears to be more important in determining the timing of meals
Low blood glucose levels activate lateral hypothalamic neurons in the vicinity of appetite centers

22. Factors control food intake
Psychosocial and environmental influences
Stress, anxiety, depression and boredom →unrelated to energy needs
Food supplies are abundant

23. Energy 0utput Internal work External work: Na＋- K＋pump
muscle contraction (shivering) or maintain the posture
External work:
go upstairs (potential energy ↑ )
lift the object from low site to high one

24. Energy 0utput Form of energy output
Heat (During biochemical processing)
75% of the energy is lost as heat (directly)
25% of the energy is available to accomplish work (internal work or external work) (indirectly)
Energy in Nutrient molecules
50%
ATP
25% lost as heat during expenditure
25% energy accomplish work
75% energy will be lost as heat
50%heat

25. Obesity 20%overweight greater than normal
body mass index(BMI)=height2/weight
BMI≥24: overweight
BMI≥28: obesity

26. Obesity 20%overweight greater than normal
Energy intake ＞energy expenditure
Abnormal feeding regulation
Psychogenic factor
During or after stressful situation
Neurogenic abnomality
Hypothalamas
Disturbances of the
satiety-appetite control
Genetic factor
Childhood overnutrition

27. Three possible states of energy balance
Neutral energy balance :
Energy input =energy expended
Positive energy balance :
Energy input > energy expended, store in adipose tissue , body weight increase– obesity
Negative energy balance :
Energy input < energy expended, lose weight

28. Energy Metabolism

29. Terminology metabolic rate = energy expenditure/unit of time (kcal/hr)
Heat is the end product of almost all the energy release in the body
Calorie : the basic unit of heat energy
--the amount of heat required to raise the temperature of 1g of H2O 1℃

30. Method of metabolic rate determination

31. Direct calorimetry
If person doesn’t do external work, energy output = heat released, we calculate the heat liberated from the body in a given time by a special calorimeter. so we can determinate the metabolic rate.

32. Measurement of metabolism rate
Direct calorimetry
water
thermometer
thermometer
Thick insulation
water

33. Measurement of metabolism rate
Indirect calorimetry
Principle:
food + O2→CO2+H2O+energy(heat)
C6H12O6+6O2 → 6CO2+6H2O + H (law of definite proportions )

34. Measurement of metabolism rate
Indirect calorimetry
Energy (Thermal) equivalent of food
Heat production (The amount of energy liberated ) by oxidation or combustion of 1g of such food
physical caloric value and biological caloric value
Energy equivalent of oxygen
Heat production (The amount of energy liberated ) by consuming of one liter of oxygen to oxidize a specific type of food
glucose: 5.01 kcal,
fat: 4.7 kcal,
protein: 4.6 kcal

35. typical mixed diet is 4.8 Kcal

36. metabolic rate = energy expenditure/unit of time
Indirect calorimetry
An average estimate of the quantity of heat produced per liter of O2 consumed on a typical mixed diet (Energy equivalent of oxygen )
liter/hr =O2 consumption
× Kcal/liter =energy equivalent of O2
Kcal/hr =estimated metabolic rate ?
metabolic rate = energy expenditure/unit of time

37. Indirect calorimetry Method of measuring O2 consumption
Closed circuit method

38. law of definite proportions
C6H12O6+6O CO2+6H2O + H
Heat = thermal equivalent of oxygen ×the amount of O2 consumed
Metabolic rate = Thermal equivalent of oxygen (4.825kcal/L)×oxygen utilized(L).

39. Counterbalancing weight
water
Recording drum
Soda lime
Mouth piece
Counterbalancing weight
volume
time

40. Factors affect the energy metabolic rate
Physical activity

41. Factors affect the energy metabolic rate
Psychic activity
stress elicits 他和secretion of the hormone epinephrine,chich increases the metabolic rate

42. Factors affect the energy metabolic rate
Thermogenic effect of food
Specific dynamic action of food
the metabolic rate of a person increases after a meal. Protein increase it significantly.

43. Factors affect the energy metabolic rate
Environment temperature:
>30℃ or <20 ℃ metabolic rate↑

44. Rate of energy expenditure for a 70kg person during different types of activity
Form of activity energy expenditure (Kcal/h)
Sleeping
Sitting at rest
Typewriting
Walking slowly on level
Bicycling on level
Swimming
Jogging
Rowing
Walking up stairs

45. Basal metabolic rate (BMR)

46. BMR The minimum energy expenditure for the body to existence
the heat output in kilocalories per hour per square meter of surface area is normally about the same.

47. BMR is not the lowest metabolic rate, metabolic rate will reduce further in deep sleep

48. Basal metabolic rate (BMR)
minimal waking rate of internal energy expenditure under basal condition
basal condition
physical rest: muscle and nerve relaxation
room temperature: ℃
Fasting: Not have any eaten food 12 hours before determination
waking?

49. Why should subject keep awake?

50. Method for determining BMR
Under the following condition
At physical rest
At mental rest
At a comfortable room temperature
Avoiding Specific dynamic action of food

51. The meaning of determining the BMR
For a healthy person, the BMR does not vary more than 10 to 15 percentage from the normal values.
Hyperthyroid: increase 25%~80%
Hypothyroid: decease 20%~25%

52. Other factors affected the BMR
Gender and age

53. Other factors affected the BMR
Hormone
Thyroid hormone : BMR↑
Male sex hormone
Sleep and malnutrition
Deep sleep : BMR↓ ↓
BMR is not the lowest metabolic rate,
metabolic rate will reduce further in deep sleep

54. how to compare MR of different person?

55. Because sex age height and weight affect the basal rate of energy expenditure.
the output in kilocalories per hour per square meter of surface area is normally about the same.
The BMR is usually expressed as calories per hour per square meter of body surface area

56. Data used to measure energy Thermal( Energy) equivalent of food
The amount of energy liberated by oxidation or combustion of 1g of such food
thermal ( Energy) equivalent of oxygen
Heat production by consuming of one liter of oxygen to oxidize a specific type of food
the amount of the food oxidation
the amount of the O2 consumption

57. Temperature regulation

58. Why keep the temperature constantly？

59. Even moderate elevations of body temperature begin to cause nerve malfunction and irreversible protein denaturation.
Higher than 44 to 45℃, maintained for certain length of time is also fatal.
An optimum environment for the cells, it is necessary to maintain a constant body temperature.

60. Body temperature Skin temperature : Core temperature:
variation by surrounding temperature
Core temperature:
maintaining constant
the body may conveniently be viewed as a central core surrounded by an outer shell.

61. Normal core temperature
No single temperature level can be considered to be normal, it is a range

62. Influence factors of core temperature

63. Physiological fluctuation of the body temperature
Influence factors of core temperature
Circadian rhythm
Diurnal rhythmical changes with a variation of 1℃
biological clock
circadian美 [sɝ'kedɪən] biological clock

64. Influence factors of core temperature
Sex different in body temperate
Female : check safe period
0.5 ℃
higher during the
half of the cycle
from the time of
ovulation to
menstruation

65. Influence factors of core temperature
: the older , the lower

66. Influence factors of core temperature
Emotional stress:
Food :specific dynamic action of food
Drugs: tranquilizer

67. Temperature regulation
Heat gain must balance heat loss to maintain a stable temperature

68. Temperature regulation
Heat production
Major organs of heat production in the body

69. Temperature regulation
Modes of heat production
Shivering thermo-genesis:
rhythmic oscillation skeletal muscle contractions
Non - shivering thermo-genesis
brown fat : a special fat tissue in newborn
Mediated by hormone: Thyroid hormone and epinephrine
Important for newborns (lack the ability to shiver)

70. Temperature regulation
Heat loss (down temperature gradient)
By skin
By expiration, urination
and defecation
By panting

72. Temperature regulation
How heat is lost from the skin surface? (down a thermal gradient)
Radiation (60%) :by Infrared heat rays
emission or absorption depend on the difference in temperature between the surface of skin and other object in the environment
camouflage clothes
camouflage clothes 迷彩服

73. Temperature regulation
How heat is lost from the skin surface?
Conduction : in direct contact with each other
Conduction to solid subjects
Conduction to air
Effect of clothing on
conductive heat loss

74. Temperature regulation
How heat is lost from the skin surface?
Convection (air or water current)
Cooling effect of wind

75. Conduction and convection
Similarity:
direct heat transfer to the material which contacts with the body
Dissimilarity
conduction :Heat transfer to and from solids
Convection: heat is transferred from the skin by conduction to the air
heated air moves away from the skin, more heat is lost to the unheated air that is continually brought in contact with the skin

76. Temperature regulation
How heat is lost from the skin surface?
When T Environmental ＞ T skin ,evaporation is the only avenue for heat loss
body is gaining heat by radiation and conduction
0.58 Calorie of heat is lost
for 1g water that evaporates

77. Temperature regulation
How heat is lost from the skin surface?
Evaporation (T Environmental ＞ T skin )
Insensible evaporation : airways and surface of skin (without controlled , passive)
450ml – 600ml H2O/day (fluid infusion)
Sensible evaporation: sweat (hot , humid days)
Sweat gland: sympathetic
cholinergic nerve innervations
Evaporating and dripping
of sweat

80. Regulation of body temperature
temperature-regulating centers: hypothalamus
Afferent input
Peripheral thermoreceptors:
Skin
cold and warmth receptor
more cold receptors than warmth receptors
Central thermoreceptors :
hypothalamus itself

82. Temperature regulation (Control of heat loss)
Posterior region of hypothalamus
activated by cold
triggers reflexes :mediate heat production and heat conservation.
skin vasoconstriction
Increase in heat production
Anterior region of hypothalamus,
activated by warmth
initiates reflexes :mediate heat loss
Vasodilation
sweating
Decrease in heat production

83. Temperature regulation
Nervous feedback mechanism (short term)
Humeral regulation : thyroid gland hormone( long term )
Behavioral control : shivering

84. Temperature regulation
Hypothalamus : sensitive thermostat
The concept of set point: thermostat
Any deviation from a very critical body core temperature, between the level of 37.0 and 37.1℃, would cause drastic change in both the rate of heat loss and heat production, then bring the body temperature back to set point

86. T skin T core Peripheral thermo receptors (skin)
Central thermo receptors (in hypothalamus)
Hypothalamus thermoregulatory center
Behavioral adaptations
Sympathetic nervous system
Motor neurons
sweating
Muscle tone
Skin vaso -constriction and vasodilation
Control of heat production or loss
Major thermoregulatory pathway

87. Abnormality temperature regulation
Fever : the point is reset at an elevated temperature.
endogenous pyrogen: raise the “set-point” .(PG↑) (Aspirin )

88. Hyperthermia : no related to infection
--malfunction of the hypothalamic control centers
Hyperthermia in sustained exercise:
heat loss mechanism reflexly increased

89. Abnormality temperature regulation
Heat stroke
Breakdown of the hypothalamic thermoregulatory systems
Prolonged exposure to a hot humid environment

90. Abnormality temperature regulation
Frostbite
Excessive cooling of
a particular part of the
body , the tissue in that
area is damaged

91. Summary Definition List the factors that affect energy metabolic rate
Specific dynamic action of food
Basal metabolic rate
body temperature
Set point
List the factors that affect energy metabolic rate
Describe the modes of heat-loss from the skin

92. Question
How does the body actively maintain a constant body temperature despite changes in ambient temperature?