Pineal gland (or epiphysis): functions and anatomy

Within the brain there are numerous structures with very diverse functions, which are connected with a large number of body systems. Although in general we can consider that the nervous system has an effect on the rest of the systems body, some of the structures that are part of it are also considered part of other systems bodily.

This is the case of the pineal gland or epiphysis, which in addition to part of the nervous system is an important part of the endocrine system.

Pineal gland or epiphysis

Considered by Rene Descartes as the place where the animal spirits lived that governed processes such as sensitivity, imagination, impulsiveness or emotion, the nerve center where the human soul lived, the pineal gland has been studied for many centuries.

The first records on the study of this structure date from the third century BC, in which it was proposed that it regulated the flow of thoughts. Later it would be analyzed by Galen, Descartes and other multiple thinkers and professionals from various fields. The study of the pineal gland advanced and deepened especially from the 20th century, in which

their functions began to be scientifically studied from the study of cases of patients with tumors in this area.

To this day, we know that the pineal gland or epiphysis is a structure located in the dorsomedial part of the diencephalon, between the superior colliculi and above the third cerebral ventricle. It is an endocrine regulation center that participates in a multitude of different fundamental processes for the development of the organism, sending different hormones to the blood circuit.

With a shape similar to that of a pine cone (similarity from which it derives its name), the pineal gland has interesting properties, since shown to be photosensitive, reacting to ambient lighting level. Similarly, it appears to be affected by external chemicals and even electromagnetic waves.

Irrigation and innervation

The pineal gland is strongly irrigated at the blood level, at a level similar to that of the kidneys. It is a structure that actively participates in the secretion of various hormonesThe main one being melatonin but also influencing the emission of follicle-stimulating and luteinizing hormones. Later these hormones reach the blood, which carries them to your target organs.

With regard to the nerve connections of the pineal gland, it is innervated by the autonomic nervous system, both by the branches nice What parasympathetic. At the sympathetic level, its main nerve connection is the superior cervical ganglion. Regarding the ganglia that innervate it at the parasympathetic level, we can find the otic and pterygopalatine ganglion.

Main functions: what do you participate in?

The pineal gland is a relevant structure linked to various situations. Being part of both the nervous system and the endocrine system, its basic functioning is the emission of various hormones that will alter different brain nuclei and other systems bodily.

Specifically, we can establish that some of the main functions of this structure are the following.

1. Regulation of biorhythms

The pineal gland is the part of the brain that, in reaction to the amount of light present in the environment, is responsible for secreting melatonin. Synthesized from serotonin, this hormone is involved in regulating the Cardiac rhtyms and infradianos, with what being the main secretor of melatonin the epiphysis has a primary function in regulating the sleep-wake cycle.

When visual information from the optic nerve reaches the epiphysis (having passed through the nucleus suprachiasmatic) superior cervical ganglion, indicates that the ambient lighting is low or non-existent, the gland pineal proceeds to secrete the hormone known as melatonin, which will later be sent to different brain regions. In the presence of lighting, however, the production of melatonin is inhibited.

2. Development and maturation

Some of the modern medical cases that have stimulated the investigation of the epiphysis o pineal gland reflected a fact that has subsequently been verified at an experimental level: the epiphysis have a great relevance in establishing the onset of puberty. In these cases, adolescents with tumors in this gland manifested precocious puberty. Subsequent research has put this fact in relation to the production of melatonin from this structure.

During the first years of life the pineal gland is strongly activated, decreasing the production of melatonin towards the eight to twelve years, at which time the first physiological changes begin to take place that will culminate in the transition from child to adult. Thus, through various investigations pineal gland activity has been shown to delay puberty, starting this stage of life when it is less active. In other words, another of the main functions of the pineal gland is to regulate the entrance to sexual maturity.

3. Sexual behavior

The pineal gland actively participates in the secretion of various hormones, including some of those that govern the menstrual cycle in women, specifically luteinizing and follicle-stimulating hormones.

In addition to this, by regulating biological rhythms through melatonin, the epiphysis also influences seasonal sexual behavior in other animal species. The pineal gland interacts with other structures related to sexuality, such as the septal nuclei, to guarantee the correct operation in this activity which is so important from the point of view of evolution.

4. Excitement and happiness

The involvement of the epiphysis or pineal gland in the emotional sphere is highly relevant. In addition to other hormones with an effect on mood, the pineal gland participates in the generation of endorphins, the hormones that they provoke states of happiness and allow to regulate pain. In fact, its involvement in the limbic system makes it a fundamental component of emotional processes, which depend on the interaction between the brain and the organs throughout the body that secrete hormones.

5. Pigmentation

While it may not seem as relevant as the ones above, melanin secreted by the pineal gland participates in the pigmentation of the skin, giving a slightly dark tone in multiple species. This function is secondary, and in fact there are genetic variants of the human being in which melanin has little effect on the way in which the skin tone changes. On the other hand, in the cases of albinism this function disappears, with all the biological and social problems that this entails.

6. Participation in other aspects

Apart from its participation in the aforementioned, the pineal gland participates in other processes. For example, it has been shown that has to do with the regulation of body temperature. Likewise, the hormones it generates also have an effect on aspects such as attention, concentration, memory and other higher mental functions. Keep in mind that virtually any brain structure linked to hormone secretion has an effect on cognition, and the pineal gland is no exception.

Bibliographic references:

• Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.

• Triglia, A.; Regader, B. and García-Allen, J. (2016). Psychologically speaking. Barcelona: Paidós.