Why do people feel hot when the temperature is 37 degrees, but feel cold when the water temperature is 37 degrees in the bath?
Our core temperature is about 37 degrees. Hypothalamus as human body? Thermostat? Keep our bodies in dynamic balance. That is to say, the generated heat is equivalent to the lost heat, thus maintaining the stability of the body temperature of 37 degrees. The human body is like an engine that constantly generates heat, a contracting heart, moving muscles, ionic mercury that maintains nerve activity, and biochemical reactions such as decomposing food and synthesizing new tissues. These are continuous heat generation, so under normal circumstances, our bodies urgently need to emit heat and rely on blood circulation to bring core high-temperature blood to the limbs. Inhale cool and dry air and spit out moist and warm air. The most important thing is sweating. Sweat evaporation on the body surface takes away a lot of heat and helps to cool down. Therefore, whether it is air temperature or water temperature, when the outside temperature is greater than 37 degrees, we need to use the above methods to dissipate heat. Whether the temperature outside is suitable or not depends on the medium of our body. In still air, it is about 2 1 degree to 27 degrees. In still water, it is about 28 degrees to 33 degrees. They are different because water and air have different heat transfer capabilities. The heat transfer ability of water is much better than that of air, and it is also to maintain your body temperature. The temperature is lower than the water temperature to achieve the same heat dissipation efficiency.
The same 37 degrees, temperature 37 degrees, water temperature 37 degrees. Here we need to add a concept, that is, temperature sensor. If the hypothalamus is a thermostat to maintain the core body temperature of 37 degrees, then the temperature sensor is a small sensor widely distributed in all parts of the body, so the external temperature we feel is different. In fact, it is also because the temperature sensors distributed on the body surface perceive the temperature difference between the skin and the outside world. When the temperature is 37 degrees, we sweat wildly, and water molecules evaporate to absorb a lot of energy, which makes your body surface temperature drop rapidly. A large number of temperature sensors in the skin sense the temperature difference between the skin and the outside world, so it feels particularly hot, but the heat dissipation efficiency is acceptable. The water temperature is 37 degrees. If we take a bath in water, our skin temperature will quickly rise to about 37 degrees. Because of the super conductivity of water to maintain the core body temperature, we will feel very hot at first, then we will feel warm and comfortable soon, and we will feel a little hot after soaking for a long time. If it is a shower, the flowing water speeds up the temperature transfer. The outside temperature is usually lower than 37 degrees, so heat dissipation is not a problem at all, so 37 degrees may be a little cold, and the temperature of bath water will rise to 38 degrees to 42 degrees before it feels comfortable.