Pineal gland (or epiphysis): functions and anatomy

In the brain there are many structures with very diverse functions, which are related to a large number of bodily systems. Although the nervous system can generally be considered to have an effect on other bodily systems, some of the structures that are part of it are also considered to be part of other bodily systems.

This is the case with the pineal gland or the epiphysis, 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 animal spirits inhabited processes such as sensitivity, imagination, impulsivity or emotion, the nerve center where the human soul lived, the pineal gland has been studied for many centuries.

The first records of the study of this structure date from the third century BC, in which it was proposed to regulate the flow of thoughts. It will then be analyzed by Galen, Descartes and many other thinkers and professionals from various fields. The study of the pineal gland progresses and deepens especially from the twentieth century, when start to study its functions scientifically from the case study of patients with tumors in this area.

Today, we know that the pineal gland or epiphysis is a structure located in the dorsomedial part of the diencephalon, between the superior colliculi and on the cerebral third ventricle. It is a center of endocrine regulation that participates in many different processes fundamental to the development of the body, sending different hormones into the bloodstream.

With a shape similar to that of a pine cone (similarity from which it gets its name), the pineal gland has some interesting properties, such as it was found to be photosensitive, reacting to the ambient lighting level. Likewise, it appears to be affected by external chemicals and even electromagnetic waves.

Irrigation and innervation

The pineal gland is strongly supplied with blood, at a level similar to that of the kidneys. It is a structure which actively participates in the secretion of various hormones, The main one being melatonin but also influencing the emission of follicle-stimulating and luteinizing hormone. These hormones then reach the bloodstream, which carries them to their target organs.

As for the nerve connections of the pineal gland, they are innervated by the autonomic nervous system, both sympathetic and parasympathetic branches. At the sympathetic level, its main nerve connection is the superior cervical ganglion. As for the ganglia which innervate it at the parasympathetic level, we find the otic and pterygopalatine ganglion.

Main functions: what are you involved in?

The pineal gland is a relevant structure and related to various situations. As part of both the nervous system and the endocrine system, its basic function is the release of various hormones that will alter different nuclei in the brain and other bodily systems.

More precisely, we can establish that some of the the main functions of this structure are as follows.

1. Regulation of biorhythms

The pineal gland is the part of the brain which, in response to the amount of light in the environment, is responsible for the secretion of melatonin. Synthesized from serotonin, this hormone is involved in the regulation of circadian and infradian rhythms, thus being the main secretor of melatonin, the epiphysis has a primordial role in the regulation of the sleep-wake cycle.

When visual information from the optic nerve reaches the epiphysis (after passing through the suprachiasmatic nucleus), the superior cervical ganglion indicates that there is little or no ambient lighting, the pineal gland secretes the hormone known as melatonin, Which will then be sent to different regions of the brain. In the presence of lighting, however, the production of melatonin is inhibited.

2. Development and maturation

Some of the medical cases which in modernity have stimulated the investigation of the epiphysis or the pineal gland reflect a fact which was later verified at the experimental level: the epiphysis has great relevance for establishing the onset of puberty. In these cases, adolescents with tumors in this gland exhibited precocious puberty. Subsequent research has linked this fact 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 around the age of eight to twelve, when the first physiological changes begin to develop which will culminate in the transition from child to child. ‘adult. Thus, through various surveys Pineal gland activity has been shown to delay puberty, Start 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 entry into sexual maturity.

3. Sexual behavior

The pineal gland actively participates in the secretion of various hormones, some of which govern the menstrual cycle in women, especially 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 ensure the proper functioning of this activity so important from the point of view of evolution.

4. Emotion and happiness

Of great importance is the involvement of the epiphysis or the pineal gland in the emotional realm. In addition to other hormones that affect mood, the pineal gland is involved in the generation of endorphins, hormones that they cause states of happiness and help regulate pain. In fact, its involvement in the limbic system makes it a key part of emotional processes, which depend on the interaction between the brain and organs distributed throughout the body that secrete hormones.

5. Pigmentation

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

6. Participation in other aspects

Besides participating in what has been discussed, the pineal gland participates in other processes. For example, it has been shown that it is the regulation of body temperature. Likewise, the hormones it generates also have an effect on aspects such as attention, concentration and memory. other higher mental functions. It should be noted that virtually any brain structure related to the secretion of hormones has an effect on cognition, and the pineal gland is no exception.

Bibliographical references:

  • Kandel, ER; Schwartz, JH and Jessell, TM (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Inter-American. Madrid.

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

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