A pineal gland It is located, in humans, approximately in the center of the brain. It is a small structure that has the shape of a pine cone, hence its name. The pineal gland of vertebrates acts on the photoneuroendocrine system, which allows these animals to understand the rhythmicity of the passage of time. The pineal gland is responsible for producing hormonemelatonin.
Read more: Endocrine system — is a complex system made up of the endocrine glands of our body
summary about pineal gland
It's a little gland located approximately in the center of the brain.
The hormone it produces is melatonin.
Melatonin secretion follows a daily cycle.
Melatonin, among other roles, is related to the promotion of sleep.
Melatonin is used in clinical medicine to treat, for example, sleep disorders.
Pineal gland
Apineal, formerly called the epiphysis, is a small gland located nearO to the center of the brain. It has a conical shape, its largest diameter is less than 1 cm, and it weighs about 150 mg. The pineal gland is covered externally by the pia mater meninges, from which septa come out that penetrate the gland and divide it into lobes.
Two cell types predominate in the pineal gland, pinealocytes and astrocytes. Pinealocytes make up about 95% of pineal cells and are the cells responsible for melatonin production and some peptides. Among the pinealocytes, astrocytes are found.
The pineal gland responds to light stimuli received by our eyes, more precisely by the retina, and transmitted to the cerebral cortex. From the cortex, stimuli are relayed to the pineal gland via nerves belonging to the sympathetic system.
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Pineal gland function
The pineal gland has been known since antiquity. Until the 19th century, studies about it were done mainly by philosophers, and it was related to metaphysical and mysterious functions. Currently, it is known that the pineal gland is related to the synthesis ofmelatonin and acts like circadian rhythm pacemaker (24 hour cycle). The gland is recognized as one of the main components of the so-called biological clock.
In some species animals, the pineal gland acts on the seasonal fertility control. Although the mechanism is not completely understood, it is known that melatonin and other substances produced by the pineal fall into the bloodstream and reach the pituitary, reducing the release of the hormone gonadotropic.
It is believed that, in the winter months, when the duration of the dark period is longer, there is an inhibition of the gonads. In spring, the secretion of the gonadotropic hormone overcomes the inhibitory effects promoted by the pineal, and the functioning of the gonads returns to normal. The relationship of the pineal gland with reproduction in humans is not yet known, but it is believed that it may play a role in this important function.
melatonin
Amelatonin is a hormone produced by the pineal gland and synthesized from serotonin in a sequence of reactions. This hormone has peak production during the night, and its secretion is made into the bloodstream immediately after synthesis. Melatonin, therefore, is not stored.
The onset of secretion occurs about two hours before the usual bedtime, and the daily production of the hormone follows a rhythmic production synchronized with the lighting cycle of the environment. The production of the hormone is suppressed by interruption of the dark by artificial light, and ambient light at night can completely block melatonin synthesis.
Unlike other hormones, melatonin not related to feedback mechanisms. Therefore, its plasma concentration does not regulate hormone production.
Currently, several functions are described for melatonin, such as immunomodulation, anti-inflammatory, antitumor, antioxidant and circadian rhythm regulatory action. The nocturnal increase in levels of this hormone in humans has a great influence on promoting sleep.
It is worth noting, however, that melatonin is produced following the same secretion patterns in both nocturnal and nocturnal animals. as in daytime, therefore, we should not consider it the sleep hormone, but the darkness hormone, which informs whether it is day or night. Melatonin also plays a role in regulation of energy balance.
O medical use of melatonin is known for treating problems like sleep disorders and neurological and degenerative diseases that cause disturbances in sleep and biological rhythm. It is also used in situations where jet lag, that is, when there is a sudden change in the circadian cycle. O jet lag can be observed when a person travels to a region with a different time zone.
By Vanessa Sardinha dos Santos
Biology teacher
Source: Brazil School - https://brasilescola.uol.com.br/biologia/glandula-pineal.htm
