WordNet

turn or go to the port or left side, of a ship; "The big ship was slowly porting"
an opening (in a wall or ship or armored vehicle) for firing through (同)embrasure, porthole
sweet dark-red dessert wine originally from Portugal (同)port wine
a place (seaport or airport) where people and merchandise can enter or leave a country
located on the left side of a ship or aircraft (同)larboard
bring to port; "the captain ported the ship at night"
carry or hold with both hands diagonally across the body, especially of weapons; "port a rifle"
carry, bear, convey, or bring; "The small canoe could be ported easily"
drink port; "We were porting all in the club after dinner"
land at or reach a port; "The ship finally ported"
modify (software) for use on a different machine or platform
put or turn on the left side, of a ship; "port the helm"
(physical chemistry) a sample of matter in which substances in different phases are in equilibrium; "in a static system oil cannot be replaced by water on a surface"; "a system generating hydrogen peroxide"
instrumentality that combines interrelated interacting artifacts designed to work as a coherent entity; "he bought a new stereo system"; "the system consists of a motor and a small computer"
a group of independent but interrelated elements comprising a unified whole; "a vast system of production and distribution and consumption keep the country going" (同)scheme
a complex of methods or rules governing behavior; "they have to operate under a system they oppose"; "that language has a complex system for indicating gender" (同)system of rules
a group of physiologically or anatomically related organs or parts; "the body has a system of organs for digestion"
a procedure or process for obtaining an objective; "they had to devise a system that did not depend on cooperation"
the living body considered as made up of interdependent components forming a unified whole; "exercise helped him get the alcohol out of his system"
of or relating to the pituitary gland; "pituitary hormone"
the master gland of the endocrine system; located at the base of the brain (同)pituitary_gland, pituitary body, hypophysis
a grand and imposing entrance (often extended metaphorically); "the portals of the cathedral"; "the portals of heaven"; "the portals of success"

PrepTutorEJDIC

〈C〉〈U〉『港』 / 〈C〉『港町』,『港市』
(船の)左舷(さげん);(飛行機の)(機首に向かって)左側 / 左舷の,左側の / 〈かじなど〉‘を'左舷に向ける
=porthole / (船の)荷役口 / (装甲車・城壁などの)銃眼,砲門
ポートワイン(ポルトガル原産の甘口のぶどう酒で深紅色)
控え銃(つつ)の姿勢(銃をからだの正面に斜めに保持し先端が左肩の近くにくる) / 〈銃など〉‘を'控え銃にする
〈C〉(関連した部分から成る)『体系』,系統,組織[網],装置 / 〈C〉(教育・政治などの)『制度』,機構;《the~》体制 / 〈C〉(思想・学問などの)『体系』,学説 / 〈C〉(…の)『方法』,方式,やり方《+of doing》 / 〈U〉正しい方針(筋道,順序) / 〈U〉《the~》(身体の)組織,系統 / 〈U〉《the~,one's~》身体,全身
脳下垂体の(から得られた) / =pituitary gland
〈C〉(堂々とした)門,入り口 / 《複数形》《文》(大きな建物の)正門,表玄関 / 《複数形》《文》(…の)発端《+『of』+『名』》

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/08 23:33:49」(JST)

wiki en

The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands. The fenestrated structure of capillaries in the hypophyseal portal system facilitates a rapid exchange between the hypothalamus and the pituitary, with only a small amount of hormones needed to stimulate an accurate effect in the respective target organs in the body.

Peptides released near the median eminence from hypothalamic nuclei are transported to the anterior pituitary, where they apply their effects. Branches from the internal carotid artery provide the blood supply to the pituitary. The superior hypophyseal arteries form the primary capillary plexus that supplies blood to the median eminence. From this capillary system, the blood is drained in hypophyseal portal veins into the secondary plexus. The peptides released at the median eminence enter the primary plexus capillaries. From there, they are transported to the anterior pituitary via hypophyseal portal veins to the secondary plexus. The secondary plexus is a network of fenestrated sinusoid capillaries that provide blood to the anterior pituitary. The cells of the anterior pituitary express specific G protein-coupled receptors that bind to the neuropeptides, activating intracellular second messenger cascades that produce the release of anterior pituitary hormones.^[1]

Structure

The blood supply and direction of flow in the hypophyseal portal system has been studied over several years on human cadaver specimens with injection methods. Results of these studies have shown that the neural hypophyseal stalk receives arterial blood from ascending and descending infundibular branches, coming from the arteries of the superior hypophyseal arterial system. Small ascending vessels arising from the anastomoses that connect the upper with the lower hypophyseal arterial system also supply blood to hypophyseal vessels. The majority of these branches penetrate into the neural tissue to break up into capillaries for rapid hormone exchange.^[1]

Development

Proper hormone secretion in the developing fetus is crucial for its growth in the womb of the mother. In order to allow a controlled hormone secretion in the developing organs of the fetus, stimulating hormones must be exchanged in the regulating structures in the brain in early stages of the development. Hormone-exchanging blood vessels between the hypothalamus and the pituitary gland, similar to those of the hypophyseal portal system, can be observed in early developmental stages of the fetus. A study performed on ovine fetuses, about 48-67 days of gestation, showed extensive and very well-developed capillary connections between the median eminence, the pituitary stalk, and the pituitary gland. In some of the fetuses, portal capillary loops had penetrated into the median eminence. These findings suggest that, in the ovine fetus, hypothalamic releasing hormones can be transported directly via a portal vascular way to the pituitary gland that develops as early as 45 days of gestation. These experimental results give evidence for an early development of what is later the fully developed hypophysial portal system. 4,5,6

Clinical significance

Over- or under-function as well as insufficiencies of the hypothalamus or the pituitary gland can cause a negative effect on the ability of the hypophyseal portal system to exchange hormones between both structures rapidly. This can have major effects on the respective target glands, making it impossible for them to carry out their functions properly. Occlusions and other issues in the blood vessels of the hypophysial portal system can also cause complications in the exchange of hormones between the hypothalamus and the pituitary gland.

References

^ ^a ^b Molina, Patricia.E. (2010). Endocrine Physiology. Lange. (3, p. 31). ISBN 978-0-07-161301-9.

External links

http://www.llu.edu/llu/medicine/anatomy/glossary/ans102_109.html#Q103
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/anatomy.html

UpToDate Contents

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