Biothermic Concept In general, heat in the human body is produced by catabolism or the breakdown of food into other substances, and muscle activity, the side effect of which is the release of heat energy. Body temperature at rest or without stress is distributed by 20% body temperature, 15% heart, and 12% muscle mass. When exercising, Ame cells metabolize more and break down carbohydrates and glycogen to produce energy. As a result of this cellular activity, muscle contractions generally occur due to our body's activities. Heat is transmitted in our daily lives. This heat transfer is very important to us when considering many nursing implementations to meet basic needs using some of these heat transfer techniques. Basically, heat transfer can be divided into four parts: radiation, heat conduction, convection, and evaporation. 1. Heat Transfer Mechanism a.. Radiation Radiative heat transfer is a process in which heat flows from an object at a high temperature to an object at a low temperature. This heat can flow in space or even in the vacuum between these objects. For example, the use of radiation in the treatment process is the use of UV light for photo therapy in jaundiced children, infrared radiation for thermo therapy, etc. By paying attention to this mechanism, for radiation we must pay attention to the source of the radiation so that the dose we give can be correct. b. Conduction Conduction is the event of heat transfer through a substance without being accompanied by movement of the constituent particles. If one end of a metal rod is heated, the other end of the rod will also feel hot. We often use the conduction method in implementing nursing care, namely hot or cold compresses to reduce pain. c. Convection Convection is a heat transfer event accompanied by the movement of substance particles. Heat transfer by convection can occur in liquids and gases. Heat transfer occurs because there are differences in the density of substances. In application in nursing internships, you can see the fulfillment of the body temperature needs of premature neonates. When premature babies or low birth weight babies are put in incubatorby providing a light bulb to warm the temperature of the incubator room. The heat delivery process in the incubator uses a convection delivery process with air as a mediator. d. Evaporation or evaporation process is a transfer of heat that is based on heating events or combustion processes. In this case, heat transfer occurs based on evaporation, the heat source can only lose heat. Another example of the evaporation process is water that is heated and then evaporates into gas, heat produced by the human body, moisture on the surface of the skin evaporates when air passes over the body. 2. Thermoregulator Our body's heat regulation is automatic, controlled and placed in the center of the brain. The temperature control center in the brain's hypothalamus, which receives information from heat receptors, can be divided into two parts: 1) peripheral heat receptors and 2) central heat receptors. After the stimulus reaches the hypothalamus, the body reacts as follows: When the environmental temperature is lower than body temperature, heat loss will be suppressed by the following process. a. Vasoconstriction of peripheral vessels Cold stimuli from the environment allow the body to resist heat loss due to vasoconstriction of peripheral vessels. Narrowing of peripheral blood vessels results in less blood flow so that heat transport does not occur optimally and body temperature is retained in the blood. b. Increased muscle activity The initial mechanism of reducing blood flow to the periphery, the body will also activate muscle cells so that the process of catabolism of glucose, lipids or proteins into blood glucose occurs. The presence of blood glucose is needed for the formation of ATP as an energy source. The process of forming ATP comes from chemical energy which is converted into kinetic energy, so that this activity will result in muscle contraction or controlling (shivering). This energy conversion process has a side effect in the form of heat. C. Hormonal Mechanism: Adrenaline, Noradrenaline, Thyroxine, Glucocorticosteroids When the environmental temperature drops, the hormones adrenaline, noradrenaline, thyroxine and glucocorticosteroids are released in greater amounts. This hormone causes an increase in cell metabolism. This increase in metabolism also causes an increase in body temperature. However, when the air temperature outside our body is higher than body temperature, it causes the opposite reaction as follows. a) Vasodilation of blood vessels When the environmental temperature rises or exceeds body temperature, the body releases heat. Release of body temperature by dilating peripheral blood vessels and increasing peripheral blood flow. Increased peripheral blood flow is accompanied by transport of temperature through the bloodstream. After reaching the peripheral blood vessels, body heat is released from the surface of the skin b) Increased secretion from sweat glands Apart from widening the peripheral blood vessels of the dermis, it also increases sweat from the sweat glands. Sweating is intended to release body temperature on the skin surface and return it to a homeostatic state.