The hypothalamus, structure known also the vegetative brain, is the brain area that regulates the body temperature.
What is the hypothalamus?
Is a small structure that, despite of its small size, links the nervous system to the endocrine system, asides from many other roles that it has.
In terms of size, this organ is no larger than a peanut. It can be found right under the thalamus, right above the brainstem and the pituitary gland. In medical terms, the hypothalamus is the outmost-ventral part of the diencephalons and the main reason why it’s important is that it mediates most of the endocrine functions, plus the autonomic and the behavioral functions.
How does it work in order to regulate the body temperature?
The temperature-regulating system is based on a feedback system. Usually, the set point temperature of the human body is 37 Celsius degrees. If it is cold outside and the temperature drops below 34 degrees, the body risks to become hypothermic. In order to prevent that, the thermal sensors located all over the body send information to the hypothalamus via the spinal cord to stimulate the skeletal muscles in order to increase the internal temperature. The vegetative brain “tells” the skeletal muscle to start shivering until the central and peripheral thermal sensors detect the proper temperature again. Only then the process of shivering is stopped. If it’s too hot outside, the system works a little bit backwards: instead of telling the muscles to produce heat, the hypothalamus sends commands to the sweating glands to…start sweating and cool down the body.
In case of an infection, the temperature-regulating system works a bit different. Usually, the set point is increased to 40 Celsius degrees. Even if it is warm inside, the hypothalamus will send the skeletal muscles commands meant to produce heat. Therefore, they will start to shiver until it reaches the set point temperature. The whole idea behind increasing automatically the thermal set point is that most of the bacteria can not survive high temperatures. This chance is a primary form of defense that, even if it doesn’t kill the bacteria 100%, it alarms people high enough to ask for specialized medical care or just take the necessary medication.