ENERGY METABOLISM & BODY TEMPERATURE Chapter 7 ENERGY METABOLISM & BODY TEMPERATURE § 1. Energy metabolism  Introduction & definition Substantial metabolism Assimilation metabolism Dissimilation metabolism (catabolism) Energy metabolism

 Energy sources & utilization * Energy sources of living organisms Direct donator of energy: ATP Reserve form of energy: CP Energy sources: food Glucose (1 mol): aerobic glycolysis yields 38 mol ATP; anaerobic glycolysis yields 2 mol ATP Fat: 1 mol 6C fatty acid yield 44 mol ATP Protein: rarely used as energy donator

* Energy transfer & utilization More than 50% transfer to heat, Less than 50% store in the ATP & CP Utilization: synthesis & growth never conduction muscular contraction glandular secretion active absorption etc.

Energy source, reserve, transfer & utilization

 Measuring the metabolic rate * Direct calorimetry * Indirect calorimetry Principle: The law of constant proportions Several related concepts Thermal equivalent of food Thermal equivalent of oxygen Respiratory quotient (RQ) Classical & simple measurement O2 consumption & CO2 production measuring Closed & opened measurement

Thermal equivalent, Thermal equivalent of oxygen & Respiratory quotient (RQ) of 3 main nutritional substances TE TEO RQ Glucose 16.7 21.0 1.00 Protein 18.8 0.80 Fat 37.7 19.7 0.71

Direct calorimetry

Indirect calorimetry

 Factors affecting energy metabolism Exercises Concept of oxygen debt Nervous Thinking peacefully & anxious Food specific dynamic effect Environmental temperature Others: age, sex, circadian rhythm, hormones, diseases, etc.

 Basal metabolism & Basal metabolic Rate (BMR) * Definition & Law of body surface area * Under what condition BMR can be measured? In the Early morning Arousal condition Lie down peacefully with no exercises No nervous Have a good sleep last night Fasting for over 12 h Room temperature at 20~25 ℃

* Measurement NPRQ=0.82; NPTEO=20.18 kJ/L; BMR=20.18 kJ/LVo2/(m2·h) or MV: measuring volume; SV: standard volume * Physiological variation & clinical significances Physiological variation: age, sex, metabolic level Clinical significances: assistant to diagnosis of some diseases, especially for thyroid dysfunction

Clinical significance of BMR

§ 2. Body temperature & its regulation  Normal temperature (about 37℃) * Core & shell temperature * Definition of body temperature in physiology * Measurement: oral cavity, rectum, axilla, etc.  Physiological variation of the body temperature Circadian rhythm (biorhythm & biological clock), Sex, Age, Emotion & Exercises, Influences of season & district  Skin temperature & mean skin temperature

Distribution of human body temperature in different environment temperature

 Thermogenesis & thermolysis * Thermogenesis & its regulation Basal metabolism, Food specific dynamic effect, Muscular motility, Shivering & non-shivering thermogenesis Regulation: Thyroid & other hormones Sympathetic nerve, NA & A * Thermolyesis & its regulation Radiation, Conduction & Convection Insensible perspiration & Sweating Regulation: Secretion of sweat Skin circulation

 Regulation of body temperature * Thermoceptor Periphery: Cold & warm receptor Distribute in the skin, mucosa & viscus Center: Cold- & warm-sensitive neurons Distribute in the spinal cord, reticular formation of brain stem, hypothalamus, etc., especially in the PO/AH * Regulatory center: PO/AH * Theory of set point

body temperature regulation Autonomic control in body temperature regulation

Discharge frequency of hermal sensitive neurons-temperature in local barin curve