How is human body heat produced?

Heat is an inevitable result of metabolism High energy compounds such as glucose and fat release energy through degradation Some of this energy is immediately used to build other important energy compounds, such as ATP, or later used as energy sources for other functions or various metabolic processes The rest of the unused energy is turned into heat by the body Therefore, the relative efficiency of metabolic function is not high, only 25% of the total energy is directly used for the main metabolic purpose, and the remaining 75% is lost in the form of heat When we rest, the heat responsible for body temperature is mainly produced by internal organs (mainly liver and heart), while during work, moving muscles produce a lot of heat This is similar to the principle of heat increase when the motor vehicle is used Although a large amount of energy of the motor vehicle is put into operation, a large part of it is turned into heat According to this theory, tremors are the mechanism by which heat is produced by rhythmically contracting muscle fibers, so they are used as metabolites and produce more heat It is very important to keep the heat balance and keep all kinds of proteins and enzymes in the organism working properly and continuously As you can imagine, the way heat is generated is difficult to be controlled precisely by the body It's very difficult for you to accurately affect the energy output of a specific chemical reaction You can only control how many reactions occur Therefore, the body temperature is mainly adjusted by the amount of disposal Most importantly, the body's heat is transmitted through the blood Skin plays an important regulatory role Like any organ, the skin infuses blood, but the amount of blood passing through the skin depends on the body's existing regulation If there is excess heat, skin blood vessels will open, increasing the surface area and effective area, allowing more blood to flow through the skin, and heat will be discharged into the ambient air The skin will turn red and hot On the other hand, when the body heat is insufficient, the skin blood vessels contract and reduce the heat lost to the environment, and more blood flows through the blood vessels deeper than the skin; the heat here exchanges between different blood vessels, flows back to the body core and is preserved The skin becomes pale and cold In addition, sweating can also emit a lot of heat by evaporation Other ways of adjusting include shaking, changing behavior (such as walking indoors, putting on a coat and turning off a fan) The regulatory changes also involve the internal coordination of the brain, especially the heat regulatory center in the lower thalamus, which can receive the information of the skin and brain's temperature receptor Interestingly, the human body does have special tissue for heat generation, rather than heat generation in the form of waste It's just that it's more needed in childhood, and the number of adults is very small It's called brown adipose tissue This mechanism is interesting, but it only exists when the baby has not fully developed its own heat generating ability, and when the muscle activity is not coordinated Brown adipose tissue is less abundant in adults because it is less important for general thermal homeostasis.