The most characteristic part of the brain is its surface full of folds and cracks, but underneath this layer of cells are many other brain structures without which we could neither think nor adapt to the environment. Some of them, like the cerebellum, are more or less known because they stick out and are easy to see, but others are much more hidden, like the hypothalamus .

Of course, the fact that the hypothalamus is small and rather more discreet than other parts of the brain doesn’t give us any idea about its importance. The role that the hypothalamus plays in our survival is extremely important , because, among other things, it is in charge of coordinating and communicating two apparently independent worlds: that of neurons and that of the hormones that navigate our blood.

What is the hypothalamus?

The hypothalamus is, along with the thalamus, one of the parts of a brain structure called the diencephalon , which is located in the center of the human brain, below the cerebral cortex and above the brain stem.

Its name is a direct reference to the place it occupies: “hypothalamus” literally means “under the thalamus”. In fact, if we look at the drawing of a sagittal split of the human brain we see that the hypothalamus seems to be the mount of the thalamus, which is much larger .

Functions of this part of the brain

The hypothalamus is one of the brain structures with the most important role in the regulation of moods , body temperature, sleep, sexual impulses and hunger and thirst.

Because of its relationship with the regulation of emotions and physiological states, the hypothalamus is considered to be part of the limbic system, the set of parts of the brain directly related to the generation of emotions.It can be said that the hypothalamus is in charge of setting in motion and coordinating among themselves a good part of the processes that allow us to survive and adapt to changing situations.

In addition, the hypothalamus is located near the brain stem because it is involved in the basic functions that ensure our survival and are therefore performed involuntarily, without our knowledge. In addition to acting as a bridge between the brain and the endocrine system, coordinates everything that is done through the autonomic nervous system , that is, the one that sends orders to parts of the body so that they adapt to each situation.

Among the processes that regulate the hypothalamus are

  • Sleep levels and the circadian cycle
  • Sexual arousal and the behavior associated with it.
  • The level of hunger.
  • Blood pressure.
  • The muscle tension.
  • Body temperature.
  • The energy levels available.

A vital process: homeostasis

The hypothalamus is constantly receiving information from all parts of the body and sending orders accordingly, because its task is to make sure that nothing that happens inside the body breaks the balance of how the whole body should work . That’s why it works as a mediator of different parts of the body, whether they are in contact with the brain or not; to influence the more distant parts, it allows the release of hormones into the blood that in a matter of minutes reach their destination to trigger the necessary process.

For example, if we see something that can be potentially dangerous, the hypothalamus will ensure that everything that happens in the body works in a way that is consistent with the readiness to react quickly. It will not allow the heart to start beating rapidly without many other organs acting accordingly: the muscles will tense up, the amount of energy available in the blood will increase, etc.

Similarly, if we have not eaten the hypothalamus for a long time, it will cause the neurons of the limbic system to generate dynamics that make the sensation of hunger appear, while at the same time it will intervene in the way in which fats and sugars available in the body are burned. All this at the same time, so that there is always a balance and the property of homeostasis is maintained, that is, the capacity to maintain stability in the functioning of things.

The hypothalamus and its connection to the pituitary gland

The fact that the hypothalamus is involved in the regulation of many vital functions means that it must be able to send commands to very different parts of the body. In addition, some of the effects it has to produce must be more or less instantaneous, while others appear with a delay and remain active for longer.

How does the hypothalamus manage to encompass this whole range of responsibilities? Well by acting as a hinge between the nervous system and the endocrine system . As the hypothalamus is inserted in a very well communicated place in the brain (it is very close to its centre), its connection with the rest of the nervous system is very easy, but it also connects with the endocrine system through a small structure called the pituitary gland .

The pituitary is located just below the hypothalamus, and is very well connected to it, so is dedicated to executing the commands that the hypothalamus passes to it: basically, it causes hormones to be released. The hypothalamus crosses data from the nervous system with the data it receives about the amount and type of hormones circulating in the blood.

When it detects an imbalance, it causes the pituitary to secrete certain hormones that will be introduced into the bloodstream and either alter the functioning of certain organs or cause other parts of the body to secrete other hormones in turn. This will adjust the biological processes needed to improve the chances of survival.

Because the hypothalamus has effects on both the brain and many other parts of the body that react to the presence of the hormones in the blood , its effects are felt in a matter of both milliseconds and minutes.