Pineal gland

The pineal gland or epiphysis, is a small endocrine gland. It is located near the center of the brain, between the two hemispheres and near the central switching point of the thalamic bodies. It is also referred to as the pineal body.

Function

It is responsible for the production of melatonin, which has a role in regulating circadian rhythms. Melatonin is a derivative of the amino acid tryptophan. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light. Light can be detected by the suprachiasmatic nucleus (SCN) which has direct connections to the retina. Fibers extend from the SCN to the spinal cord via the periventricular nuclei (PVN) into superior cervical ganglia (SCG) and from there into the pineal gland.

Related Topics:
Melatonin - Circadian rhythm - Amino acid - Tryptophan - Suprachiasmatic nucleus - Spinal cord - Superior cervical ganglia

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Ancient amphibians such as Ichthyostega, which existed in the Late Devonian Period, had an orifice on the top of the skull through which the pineal gland was exposed and received light input. Over the course of time and for unknown reasons, the pineal gland migrated into the skull of later tetrapods and the skull orifice sealed. Modern birds and reptiles have been found to express the phototransducing pigment melanopsin in the pineal gland. Avian pineal glands are believed to act like the suprachiasmatic nucleus in mammals.

Related Topics:
Amphibians - Ichthyostega - Devonian - Tetrapods - Bird - Reptile - Phototransducing - Pigment - Melanopsin - Suprachiasmatic nucleus - Mammal

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It also contains a substance which if injected intravenously causes fall of blood-pressure. It seems probable that the gland furnishes an internal secretion in children that inhibits the development of the reproductive glands since the invasion of the gland in children, by pathological growths which practically destroy the glandular tissue, results in accelerated development of the sexual organs, increased growth of the skeleton and precocious mentality.

Related Topics:
Sexual organs - Skeleton

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Additionally, it has been found that the pineal gland manufactures trace amounts of the psychedelic chemical dimethyltryptamine, or DMT. This endogeous chemical in the human brain is believed to play a role in dreaming and possibly near-death experiences and other mystical states. It has been suggested by the researcher Jace Callaway that DMT is connected with visual dreaming.

Related Topics:
Psychedelic - Dimethyltryptamine - Dreaming

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