pineal gland

pineal gland
a small, cone-shaped endocrine organ in the posterior forebrain, secreting melatonin and involved in biorhythms and gonadal development. Also called epiphysis. See diag. under brain.
[1705-15]

* * *

Endocrine gland in the brain that produces melatonin.

It is large in children and begins to shrink at puberty. The gland may play a significant role in sexual maturation, circadian rhythm and sleep induction, and seasonal affective disorder and depression. In animals it is known to play a major role in sexual development, hibernation, and seasonal breeding.

* * *

      endocrine (endocrine system, human) gland found in vertebrates that is the source of melatonin, a hormone derived from tryptophan that regulates circadian rhythm ( sleep cycle). The pineal gland develops from the roof of the diencephalon, a section of the brain. In some lower vertebrates the gland has a well-developed eyelike (eye, human) structure; in others, though not organized as an eye (eye, human), it functions as a light receptor.

      The pineal gland is located at the posterior end of the third cerebral ventricle in the midline of the brain. Its name is derived from its shape, which is like that of a pine cone (Latin pinea). In adult humans it is about 0.8 cm (0.3 inch) long and weighs approximately 0.1 gram (0.004 ounce). The gland is relatively large in children and begins to shrink with the onset of puberty. In adults small deposits of calcium often make the pineal body visible on X-rays.

      The endocrine function of the gland is to produce melatonin. In several vertebrate species the pineal plays a major role not only in sexual development but also in hibernation and seasonal breeding. In humans, however, its function is less well understood. Melatonin production is high in infancy and childhood and declines with age. High levels of melatonin in children may contribute to delay of sexual development. Melatonin secretion increases during darkness and is inhibited by light. Disordered melatonin secretion may contribute to sleep disorders, jet lag, and depression. However, administration of melatonin has very limited efficacy in the treatment of these problems.

Robert D. Utiger
 

* * *


Universalium. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Pineal gland — Diagram of pituitary and pineal glands in the human brain Latin glandula pinealis Gray s …   Wikipedia

  • Pineal gland — Pineal Pi ne*al, a. [L. pinea the cone of a pine, from pineus of the pine, from pinus a pine: cf. F. pin[ e]ale.] Of or pertaining to a pine cone; resembling a pine cone. [1913 Webster] {Pineal gland} (Anat.), a glandlike body in the roof of the… …   The Collaborative International Dictionary of English

  • Pineal gland — A small gland located deep within in the brain. It is believed to secrete melatonin, and may therefore be part of the body’s sleep regulation apparatus. * * * pineal gland n a small body that arises from the roof of the third ventricle and is… …   Medical dictionary

  • Pineal Gland 418 — (Miranda,Бразилия) Категория отеля: Адрес: Avenida Nicola Candia, 418, Miranda, CE …   Каталог отелей

  • pineal gland — pineal body a pea sized mass of nerve tissue attached by a stalk to the posterior wall of the third ventricle of the brain, deep between the cerebral hemispheres at the back of the skull. It functions as a gland, secreting the hormone melatonin.… …   The new mediacal dictionary

  • Pineal gland cyst — A pineal gland cyst is a cyst in the pineal gland, a small endocrine gland in the brain.. Statisically, these fluid filled bodies appear on 1 4% of magnetic resonance imaging (MRI) brain scans. They are more frequent at death, seen in 21 41% of… …   Wikipedia

  • pineal gland — noun a small endocrine gland in the brain; situated beneath the back part of the corpus callosum; secretes melatonin • Syn: ↑pineal body, ↑epiphysis cerebri, ↑epiphysis • Hypernyms: ↑endocrine gland, ↑endocrine, ↑ductless gland …   Useful english dictionary

  • pineal gland — [ pɪnɪəl, pʌɪ ] (also pineal body) noun a pea sized conical mass of tissue behind the third ventricle of the brain, secreting a hormone like substance in some mammals. Origin C17: from Fr. pinéal, from L. pinea pine cone (with ref. to the shape… …   English new terms dictionary

  • pineal gland — noun Date: 1712 a small usually conical appendage of the brain of all craniate vertebrates that functions primarily as an endocrine organ and that in a few reptiles has the essential structure of an eye called also pineal, pineal body, pineal… …   New Collegiate Dictionary

  • pineal gland — noun /pʌɪˈniːəl ˌɡland/ A small, pinecone shaped endocrine gland found near the centre of the brain that produces melatonin. Syn: epiphysis, pineal body …   Wiktionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”