Hypothalamus: definition, characteristics and functions
The most characteristic part of the brain is its surface full of folds and crevices, but beneath 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 in the end they stand out and are easy to see, but others are much more hidden, such as hypothalamus .
Of course, the fact that the hypothalamus is small and much more discreet than other parts of the brain does not give us an idea about its importance. The role that the hypothalamus plays in our survival is of the utmost importance , because, among other things, it is responsible for coordinating and communicating two apparently independent worlds: that of the neurons and that of the hormones that navigate our blood.
What is the hypothalamus?
The hypothalamus is, together with the thalamus, one of the parts of a brain structure called the diencephalon , which is found in the center of the brain of human beings, below the cerebral cortex and above the brainstem.
Its name is a direct reference to the place it occupies: "hypothalamus" literally means "under the thalamus". Indeed, if you look at the drawing of a sagittal section of the human brain we will see that the hypothalamus seems to be the thalamus mount, which is quite bulky .
Functions of this part of the brain
The hypothalamus is one of the brain structures with a more important role in the regulation of moods , body temperature, sleep, sexual impulses and hunger and thirst.
Because of its relation to the regulation of emotions and physiological states, the hypothalamus is considered 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 responsible for starting and coordinating 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 intervenes in the basic functions that guarantee our survival and that, therefore, are performed involuntarily, without us noticing. In addition to acting as a bridge between the brain and the endocrine system, coordinates everything that is done through the autonomous 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 are responsible for regulating the hypothalamus are:
- Sleep levels and the circadian cycle.
- Sexual arousal and the behavior associated with it.
- The level of hunger.
- Blood pressure
- Muscle tension
- The 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 his task is to make nothing of what happens inside the organism break the balance of how the globality of the body should work . That is why it functions as a mediator of different parts of the body, whether they are in contact with the brain or not; to influence the most distant parts, it allows hormones to be released in 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 organism works coherently with the readiness to react quickly. It will not let the heart start to beat quickly without many other organs acting accordingly: the muscles will tense, the amount of available energy in the blood will increase, etc.
Similarly, if you 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, at the same time that 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 ability to maintain stability in the functioning of things.
The hypothalamus and its connection to the pituitary gland
The fact that the hypothalamus intervenes in the regulation of many vital functions means that it must be able to send orders that reach very different parts of the body. In addition, some of the effects that have to produce must be more or less instantaneous, while others appear late and remain more active.
How does the hypothalamus to be able to cover all this range of responsibilities? Well acting as a hinge between the nervous system and the endocrine system . As the hypothalamus is inserted in a well communicated place of the brain (it is very close to its center), its connection with the rest of the nervous system is very easy, but also connects with the endocrine system through a small structure called hypophysis , or pituitary gland.
The pituitary gland is located just below the hypothalamus, and is very well connected to the hypothalamus. is dedicated to execute the orders that this happens: basically, it causes hormones to be released. The hypothalamus crosses data from the nervous system with those that arrive about the amount and type of hormones that are circulating in the blood.
When it detects some 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 this way, the biological processes necessary to improve the chances of survival will be adjusted.
Since the hypothalamus has effects both in the brain and in many other parts of the body that they react to the presence of hormones in the blood , its effects are noticeable both in a matter of milliseconds and minutes.