Quite often in modern medical practice, and in the scientific literature, one may encounter the term “pineal gland”. What it is? What functions does this structure perform? What properties does it have? These questions are of interest to many people, especially given the fact that this body is often associated with some esoteric theories.
Epiphysis - what is it?
In fact, in the human body there are two structures that are usually denoted by this term. Surely, many have heard about the bone epiphysis, which is the end section of the tubular bones.
But there is also an pineal gland in the human brain. What it is? This is a small structure, which is usually attributed to the diffuse endocrine system. By the way, there are other names for this organ, for example, the pineal gland and the pineal gland. The pineal gland is part of the so-called photoendocrine system, and, despite its relatively modest size, its role for the normal functioning of the body is simply huge.
Epiphysis of the bone and its functions
The bone epiphysis is an extended ridge of the tubular bone. This part is the articular surface that forms the joint together with the adjacent bone.
In this section, the bone tissue has a spongy structure. The surface of the pineal gland is covered with articular cartilage, and under the cartilage tissue is the so-called subchondral plate containing many nerve endings and capillaries.
Inside, the bone pineal gland is filled with red bone marrow. This structure is extremely important for the normal functioning of the human body, since it is here that the formation and maturation of red blood cells occurs.
Epiphysis (pineal gland) and its location
It is worth noting that the pineal gland is the most recently discovered and least studied part of the human brain. Of course, over the past decades, many discoveries have been made that explain the mechanism of this structure. By the way, outwardly this small organ is somewhat reminiscent of a pine cone, for which it, in fact, was called the pineal gland.
This organ is located almost in the center of the brain, between two hemispheres in the area of interthalamic fusion. It is also attached to both visual mounds located in the diencephalon.
Cell structure
The pineal gland is a small organ, painted in a grayish-red color. Outside it is covered with a dense capsule of connective tissue. The capsule forms the so-called trabeculae, which penetrate into the gland and divide it into small lobules. This is what the human pineal gland looks like - its structure can be considered quite simple.
The inner part of the gland consists of parenchyma and connective tissue elements. The main structural elements in the pineal gland are pinealocytes - polygonal parenchymal cells. In addition to them, four more types of cells were discovered - these are the pineal gland neurons, interstitial endocrinocytes, also peptidergic neuron-like structures and perivascular phagocytes.
It is worth noting that at the beginning of a person’s life, the pineal gland grows rapidly, but around the puberty, the growth of the pineal gland gradually fades. Moreover, as the human body grows older and older, gland involution occurs.
Main functions
Of course, the functions of the pineal gland are not yet fully understood. Nevertheless, it is known that the main hormone of the pineal gland is melatonin, which is responsible for the formation of the so-called circadian rhythms (sleep and wakefulness). This hormone is responsible not only for the frequency of sleep, but also helps the body adapt when changing time zones. It also acts as an antioxidant and slows down the aging process.
Of course, the pineal gland also produces some other hormonal substances. For example, iron secretes adrenoglomerulotropin, which stimulates the synthesis of aldosterone. In addition, the pineal gland performs several other important functions. For example, it inhibits the secretion of growth hormones and sexual development, prevents the formation and growth of tumors, strengthens the immune system. It is believed that the hormones of the pineal gland to one extent or another control the work of the hypothalamic-pituitary system, thereby affecting the work of all the endocrine glands of the body.
Regulation of functioning
It is worth noting that the features of the work and regulation of the pineal gland are still poorly understood. Research is difficult due to the small size of the gland and its location. Nevertheless, it has been proven that the pineal gland is controlled not only by the nerve endings, but is also susceptible to light.
Of course, light does not penetrate directly to the pineal gland. Nevertheless, photons irritate specific ganglion cells of the eye retina. From here, the nerve impulse is transmitted to the suprachiasmal nucleus of the hypothalamus, from where it is sent through the paraventricular nucleus to the upper segments of the thoracic spinal cord. From here, excitation is transmitted to the pineal gland through the superior cervical ganglion. It is worth noting that the impulse that occurs in the suprachiasmal nucleus does not stimulate, but, on the contrary, inhibits the work of the pineal body. Thus, in the light, the secretion of melatonin decreases, and in the dark (at night) it increases. As for the stimulation of the pineal gland, the neurotransmitter in this case is norepinephrine.
Pineal gland disease
Of course, some diseases can affect this part of the brain. For example, often during examinations, various neoplasms are found in a structure called the pineal gland. What it is? Yes, sometimes in the tissues of the pineal gland malignant degeneration of cells occurs. The appearance of a benign tumor or cyst is observed.
Since the pineal gland is the gland of internal secretion, naturally, the hormones produced by it affect the functioning of the entire endocrine system. Even a small pineal cyst can lead to severe hormonal failure and the development of a disease called macrogenosomy. Such a disease is accompanied by a change in the level of certain hormones, which entails premature physical and sexual development (the appearance of menstruation at an early age, etc.). Often, mental retardation is observed.
Epiphysis in modern esotericism
It's no secret that a lot of mystical stories and esoteric theories are associated with the pineal body. The fact is that this organ was discovered relatively late, and hidden deep in the brain structures, which prompted some scientists and philosophers to the idea of the extreme importance of the pineal gland. For example, Rene Descartes in his works called the pineal gland "the saddle of the soul." And indeed, it was this structure for decades and even centuries that was perceived as a kind of receptacle of the human soul.
There are more ancient beliefs about the mystical "third eye", which allows a person to see the invisible and is responsible for various extrasensory abilities. For example, in the 19th century, a theory was put forward that the mysterious third eye really exists. But if in some animals it is located on the surface of the body (for example, in some cyclostomes, the pineal gland really comes to the surface and acts as a photosensor), then in humans the eye “hides” inside the skull.