What will we discuss in this chapter? (Outline) I. Energy metabolism 1. Source and utilization of energy 2. Determination of energy metabolism 3. Influencing factors of energy metabolism 4. Basal metabolism II. Body temperature and regulation 1. Body temperature 2. Thermogenesis and thermolysis 3. Body temperature regulation 4. Body temperature acclimation
I. Energy metabolism1. Source and utilization of energy(1) Energy transition
(2) Energy source • Sugar：dominating energy producing material（70% of body requisite energy ） • Fat：Major energy storing substance important energy supplying material • Protein: important nutritional material
Food O2 Production, transform, release and utilization of energy Summary Muscle contraction Heat energy Heat energy Neural conduction ATP mechanical work Energy Biological oxidation C-P Anabolism ADP Others Reservedenergy Pi CO2, H2O, urea, uric acid, etc.
What is metabolism ? • All the chemical reactions in all the cells of the body. • Catabolism and Anabolism.
(4) Energy metabolism • Concept：the energy metabolism means the liberation, transformation and utilization of energy produced by the material metabolism in the body.
2. Determination of energy metabolism —Energy metabolic rate, • Direct calorimetry • Indirect calorimetry • Thermal equivalent • Thermal equivalent of oxygen • Respiratory quotient, RQ • No-protein respiratory quotient, NPRQ
Basic concepts in energy metabolism • Caloric value The caloric value of the food is the energy released by oxidation of 1 gram of such food. • Thermal equivalent of oxygen The quantity of energy liberated per liter of oxygen used in the body is called thermal equivalent of oxygen. For the average diet, it is about 4.825 calories.
Basic concepts in energy metabolism • Main form of energy in body: adenosine triphosphate, ATP. • Secondary form of energy in muscles: creatine phosphate, CP • ATP ADP + CP (stored form of ATP) • Respiratory quotient *, RQ= • Usually, RQ value is 0.85 and it can be used to assess the main content of food taken in. • Non-protein respiratory quotient, NPRQ, generally speaking, body energy main source is from the oxidization of carbohydrate and fats and protein can be neglected. Creatine Pi Mol number of producing CO2 in body per unit time Mol number of consumptive O2 in body per unit time
3. Influencing factors of energy metabolism * • Individual factors • Body surface area • Gender and age • Physiological activities and environmental factor • Sleep • Musculation • Oxygen debt • Environmental temperature • Food specific dynamic effect • Mental stress • Others
4. Basal metabolism • Basal metabolism rate, BMR*: Energy metabolism rate under the basal conditions which are morning, waking, repose, non-muscle activity, fasting more than 12 hours, room temperature (20~25ºC) and well-being sanity. • BMR and Clinic diseases
How to measure basal metabolism rate ? Basal condition： • Room temperature, 20~25℃ • Fasting more than 12 hr • Consciousness and calm • Mental peace and quiet In the early morning
II. Body temperature and regulation Big temperature difference on the earth surface at the various place: 70~+60℃ Temperature range of common life on the earth: 0~45℃ Human body temperature maintained at 35~41℃
50% Main source of body heat is from energy metabolism
1. Body temperature The body temperature is often referred to core temperature. The core refers to the central area of the body, including the brain and viscera, which are maintained at a constant temperature.
Shell temperature and core temperature • Shell temperature ： Body peripheral tissue temperature, like skin, subcutaneous tissue , muscle, etc., unstable, big difference at various parts of the body（higher at head and face, next at ventrum , lower at the limbs ending. • Core temperature ： Body internal temperature, like heart, lungs, abdominal viscera, etc., stable, little difference at various parts of the body（higher at the liver, next at the brain, lower at the kidney, pancreas, duodenum, rectum, etc., and circulatory blood could represents visceral average temperature
A: Environmental temperature 20 0C B: Environmental temperature 35 0C Body temperature and environmental temperature
（1）Definition： body temperature — Body internal average temperature. Maintenance: energy released from substance metabolism. ＞50% of heat energy → maintain body temperature Substance metabolism ＜50% of chemical energy→ATP → heat energy → body outside
(2) How to measure body temperature âThermometer : mercury thermometer; electrothermometer and semiconductor thermometer. â Place of temperature measurement: ÚRectal temperature, （36.9℃-37.9℃） ÚOral temperature, （36.7℃-37.7℃） ÚAxillary temperature, （36.0℃-37.4℃） ÚEsophageal temperature, as a target of core temperature. ÚTympanic temperature, as a target of brain temperature. Clinic use Experimental use
(3) Normal range of body temperature Average value (℃) SD Normal range (95% confidence, ℃) Axillary fossa Oral cavity Rectum 36.79 0.357 36.0～～37.4 37.19 0.249 36.7～～37.7 37.47 0.251 36.9～～37.9 Statistics from 1030 health adults` body temperature
nurse: Monitoring body temperature accurately is an important nursing measure. Body temperature reflects the heat content of the body and may provide information of the patient. • Student: What is the normal temperature of the human body? • N: The normal temperature of the human body is about 37℃. The rectal temperature is about 36.5℃-37.5℃. The mouth temperature is 0.3-0.5℃ lower than the rectal temperature . The axillary temperature is 0.2-0.4℃ lower than the mouth. • S: Then which is standard? • N: The rectal temperature is standard , because it is in the cavity of the body and nearly the temperature of the blood. • S: How many times a day do we take temperature for the patient? • N: Some patients are taken temperature twice a day and others every four hours or even every two hours. • S: When do we take the temperature for the patients? • N: Usually we take it at 8 a . m. And 4 p. M . . The feverish patients should be taken their temperature every four hours or every two hours daily. • S: Should pulse and respiration be taken while the temperature is being taken? • N: Yes , the nurse not only takes the temperature but also counts the pulse and respiration. • N: Do you know what are the precautions while taking one's temperature orally? • S: Yes . We should tell the patients to close their mouths and be careful not to break the thermometer and swallow the glass or mercury. It would be very dangerous. • S: How do you treat that if the patients swallow the mercury? • N: The patient would take some egg white or milk immediately.
(4) MST and MBT • Mean skin temperature，MST Tmst＝0.2（Tleg＋Tthigh）＋0.3（Tchest＋Tupper arm） • Mean body temperature，MBT Tmbt＝α·Tcore＋（1－α）·Tmst （Tcore is deep part temperature, usually represented by rectal temperature, αis deep part tissues/ all body tissues, 1-αis surface tissues / all body tissues)
(5) Normal changes in body temperature • 1) Circadian rhythm • Lowest at morning 2~5; highest in the afternoon 2~5, • Fluctuation＜1℃ • Circadian rhythm • The fluctuations in homeostatically regulating function that repeat in a cyclic pattern every 24 hours is called circadian rhythm.
2) Sex： Female is higher 0.3℃ than male Female body temperature rhythmically changes with menstrual cycle: Lower at preovulation; Lowest at ovulation; Rise up after ovulation.
3) Age • Newborn, irregular body temperature changes（thermoregulation is poor） • Teenagers, higher body temperature • Aged people, lower body temperature（BMR↓, exercise↓） • Emotion and physical work • Drug action • Season and area effect • 4) Muscle work *
2. Thermogenesis and thermolysis thermogenesis Body heat balance thermolysis Chemical thermogenesis and physical thermolysis inside body is mutually coordinated, restricted and controlled by the intracerebral thermotaxic centre.
(1) Thermogenesis ØThermogenesis organ: mainly, viscera under quiet condition (liver, kidney, etc.) and principally, skeletal muscle under the movement. ØBasic patterns of body thermogenesis: • basal metabolism • specific dynamic effect • contraction of skeletal muscle • shivering and non-shivering thermogenesis