Post 680 –by Gautam Shah
BMR: Basal Metabolic Rate is the amount of energy (metabolism-calories) per unit of time that a person needs to keep the body functioning, at rest. The ‘rest’ or body sustenance functions include breathing, blood circulation, controlling body temperature, cell growth, brain and nerve. The basal metabolic rate accounts for about 60 to 75% of the daily calorie expenditure by individuals. About 20% of energy expenditure comes from physical activities and another 10% from digestion of food. It is influenced by several factors, such as the age, gender, degree of acclimatization, posture and state of health. The primary organ responsible for BMR regulating metabolisms is the hypothalamus.
Our body functions as a thermo equilibrium system, with upper limits of bearing is 52° C, and lower limits of 3° C. A body may endure or adopt to certain abnormal conditions for a period of time, but there may occur side effects. The side effects may be realized in a different form and at a different time. In certain acute work conditions like mines, metal smelting plants, textile plants, cold storage, the levels of efficiency or productivity depend on the endurance level and adaptability of the body.
The human body has many minor variations, but an average temperature of 37° C. Body temperature is highest in the evening and lowest in the morning (+or- range of 1° C.) energy expenditure of the body is different for endothermic animals and fish or reptiles. In reptiles and amphibia heat regulation mechanisms is absent. Their body temperature rises or falls with the atmospheric temperature. Hence they are called cold-blooded animals. In abnormal temperature conditions they regulate the body temperature by suitable habitat like burrowing and hibernation.
Infants have a very imperfect mechanism for regulation of body temperature. A fit of crying may elevate and a cold wash may lower the body temperature. Aged persons have a low metabolism, and so maintain a lower body temperature. It takes much longer for an aged person to gain or dissipate body heat. Female body temperature is slightly lower than male. High protein foods increase the body temperature. The act ingestion and food digestion and exercise raises the body temperature. Atmospheric conditions like, temperature, humidity and movement of air, affect the efficiency of heat exchange from the body, and so the body temperature.
There are three types of heat generating processes in the human body. Conversion of food matter into useful energy, Muscular activities, and Certain infections and dysfunctions within the body, elevates or lower the body temperature by extra ordinary rate. Many physical, chemical and bacterial agents disturb the heat regulation mechanism and cause fever. These may be due to increased heat production or reduced heat loss, or both.