Pineal gland (or pineal epiphysis): functions and anatomy

A part of the brain with great importance in the regulation of hormones and sleep.

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

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

Pineal gland or epiphysis

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

The first records on the study of this structure date back to the third century B.C., in which it was proposed that it regulated the flow of thoughts. Later it would be analyzed by Galen, Descartes and many other thinkers and professionals from different fields. The study of the pineal gland advanced and deepened especially from the twentieth century onwards, in which began to be studied in a scientific way its functions from the study of from the study of cases of patients with tumors in this area.

Today, we know that the pineal gland or epiphysis is a structure located in the dorsal part of the brain. is a structure located in the dorsomedial part of the diencephalon, between the superior colliculi and over the third ventricle of the brain.. It is a center of endocrine regulation that participates in a multitude of different processes that are fundamental for the development of the organism, sending different hormones to the bloodstream.

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

Irrigation and innervation

The pineal gland is heavily supplied with blood, at a level similar to that of the kidneys. It is a structure that actively involved in the secretion of various hormones, the main one being melatonin.The main one being melatonin, but it also influences the release of follicle stimulating hormone and luteinizing hormone. Subsequently, these hormones reach the blood, which carries them to their target organs.

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

Main functions: what is it involved 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 function is the emission of various hormones that will alter different brain nuclei and other body systems.

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

1. Biorhythm regulation

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 the regulation of circadian and infradian rhythms, so that as the main melatonin secreter, the pineal gland plays a major role in regulating the sleep-wake cycle.

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

2. Development and maturation

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

During the first years of life the pineal gland is strongly activated, with melatonin production declining around the age of eight to twelve, at which time the first physiological changes begin to take place, culminating in the transition from child to adult. Thus, through various research studies, it has been shown that melatonin activity it has been demonstrated that the activity of the pineal gland delays puberty.This stage of life begins when the pineal gland is less active. In other words, another major function of the pineal gland is to regulate the entry into sexual maturity.

3. Sexual behavior

The pineal gland is actively involved in the secretion of several secretion of various hormones, among which are some of those that govern the menstrual cycle in the female, namely the hormones in women, namely the luteinizing and follicle-stimulating hormones.

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

4. Emotion and happiness

The participation of the pineal epiphysis or pineal gland in the emotional field is of great relevance. In addition to other hormones that affect mood, the pineal gland is involved in the generation of endorphins, the hormones that cause states of happiness and regulate pain. that cause states of happiness and help 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

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

6. Involvement in other aspects

Apart from its participation in the above mentioned, the pineal gland is involved in other processes. For example, it has been shown that is involved in 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. other higher mental functions. It should be noted that virtually any brain structure linked to hormone secretion has an effect on cognition, and the pineal gland is no exception.

Bibliographical 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.