Basic Introduction Chinese Name: Basic Metabolism mbth:basal Metabolism * * * * Abbreviation: BM Nature: Minimum power instrument needed to maintain organism life: Stable environment of basic metabolomer: Basic information, minimum energy metabolism, basic metabolomer, basic heat production and basic information basic metabolism are the most basic energy consumption to maintain organism life activities. The energy consumption of basal metabolism constitutes an important part of the body's energy consumption and is an important basis for studying the body's energy consumption and energy demand. The basal metabolic rate of men has physiological changes with gender and age. The average basal metabolic rate of men is higher than that of women, and that of children is higher than that of adults. The older you get, the lower your metabolic rate is. Generally speaking, the difference between the actual value of basal metabolic rate and the normal average value is within 10- 15%. When it exceeds 20% of the normal value, it can be considered as a pathological state. In hypothyroidism, the basal metabolic rate is 20-40% lower than the normal standard; In hyperthyroidism, the basal metabolic rate is 25-80% higher than the normal standard. When other functions such as adrenal cortex and pituitary gland are low, the basal metabolic rate will also decrease. The minimum power required to maintain an organism's life is abbreviated as B.M. The minimum power required to maintain an organism's life. In order to eliminate the extra energy consumption (called functional consumption) caused by muscle work, mental activity, food digestion and temperature regulation of external temperature changes, subjects should keep absolutely quiet and fast (people don't eat within 12- 18 hours), and the energy consumption at critical temperature is taken as the basic metabolic quantity. 1 natural annual human basal metabolism is 1200- 1400 kcal in Japan and 1500-2000 kcal in Europe and America, but due to the influence of daily life style, the number of kcal is not absolute. Basic metabolism inevitably includes mechanical work of heart, respiratory muscle, digestive tract and vascular smooth muscle, as well as functional consumption caused by secretory activities of liver and kidney. The basic consumption caused by the life process of each cell accounts for about 3/4. The basal metabolism of the same warm-blooded animal is directly proportional to its body surface area under the same environment. A person's body surface area S(cm2) can be calculated by weight W(kg) and height H(cm) with various experimental formulas. Dubois' (19 15) formula: S=W0.245×H0.725×7 1.84 is widely used. Japanese, the coefficient of women is 72.46, and that of men is 74.49. Of course, the basal metabolic quantity per unit body surface area also changes with age, sex, time of day 1, season, nutrition, physique, medication, pathological state and so on. People are the lowest at birth, then increase rapidly, reach the highest value at the age of 5, and then gradually decrease, generally staying the same at the age of 20-40 (above). Then it gradually decreases in old age. The value of adult women is 5-7% lower than that of men, because the proportion of adipose tissue in women is higher. The percentage of the difference between the measured value and the normal standard value (age, sex) to the normal standard value (increase in metabolism,-decrease in metabolism) is called basal metabolic rate (B.M.R), which is often used for thyroid function examination in clinic. The lowest basic state of energy metabolism is that the human body is awake and quiet on an empty stomach at room temperature 18 ~ 25℃. At this time, the minimum energy metabolism necessary to maintain basic life activities such as heartbeat and breathing is called basal metabolism (BM). Its value is related to gender, age, height, weight and health status. As mentioned earlier. All the energy generated by the body will eventually become heat energy, so in order to compare the energy metabolism level of different individuals, it can be expressed by the heat emitted by the body per hour per square meter of body surface area (kJ/h m2), that is, the basal metabolic rate (BMR). The body surface area (S) of an organism can be obtained by the following formula: S(m2)=0.006 1× height (cm)+0.0 1.28× body weight (kg)-0. 1.529 The oxygen consumption per unit time (OO) is commonly measured by basic metabometers in clinic. Because in the basic state, the conditions are relatively fixed. Through investigation, the basic metabolic rate (BMR) BMR = O2l/h× 19.3kJ/s can be obtained by substituting the mixed respiratory quotient of 0.82 and the calorific value of oxygen into the following formula, for example, the body surface area of a 30-year-old male1. The basal metabolic rate of normal people is relatively constant. Generally, men are slightly higher than women, children and adolescents are higher than adults, and gradually decrease after adulthood. Common factors Many factors will affect the heat production process. Now, only the most common factors are listed. Basal metabolism, such as hyperthyroidism, increases the body's heat production and basal metabolic rate, and when thyroid function is low, the basal metabolic rate also decreases. When muscles are active, the heat generated by bones can be increased several times, accounting for 75% ~ 80% of the total heat. The degree of increase is related to the intensity of muscle activity. For example, when walking, it will increase by about 3 times compared with the quiet state, and when exercising vigorously, it will increase by 10 ~ 20 times. When the body is engaged in busy mental work, it can strengthen the muscle tension of skeletal muscle and the activity of adrenal gland through nerve channels, and also increase heat production. The special dynamic function of food increases the body's heat production after eating for a period of time, compared with before eating. Protein food can increase the calorie output by 30%, and sugar or fat food can increase by 4% ~ 6%. When people eat common mixed foods, the daily heat production is increased by 600 ~ 800 kj due to eating. The mechanism of this phenomenon is not very clear. Environmental temperature The energy metabolism of human body is most stable in the environment of 20 ~ 30℃. When the temperature is higher or lower than this range, the heat production will increase. When the human body is cold, it first causes the reflex of muscle tension to increase, and then chills appear. Chilling refers to the unconscious and tiny rhythmic contraction of skeletal muscle. It is characterized by the simultaneous movement of extensor and flexor muscles, and almost no external work is done. At this time, all the energy consumed is converted into heat, and its maximum heat production rate can reach 39.2kJ/kg per minute, which makes the heat production of the body 4 ~ 5 times higher than usual. When the temperature is 30 ~ 45℃, the heat production of the body will also increase, which may be due to the accelerated chemical reaction in the body at this time. The activity of endocrine glands has been described above, and thyroxine can promote oxidative metabolism. Adrenaline can also enhance the oxidation reaction in cells, at the same time increase the blood sugar concentration, enhance the utilization rate of blood sugar, and thus increase heat production.