Posterior pituitary: Difference between revisions

{{Infobox anatomy

| Name = Posterior pituitary

| Caption = Pituitary gland. Posterior pituitary is in blue and Anterior pituitary is in orange. Pars nervosa and infundibular stalk are not labeled, but pars nervosa is at bottom and infundibular stalk is at top.

| Caption2 = Median sagittal through the hypophysis of an adult monkey. (Posterior lobe labeled at bottom right.)

| Precursor = [[Neural tube]] (downward-growth of the [[diencephalon]])<ref>[http://www.med.unc.edu/embryo_images/unit-nervous/nerv_htms/nerv016a.htm Embryology at unc.edu]</ref>

}}

The '''posterior pituitary''' (or '''neurohypophysis''') is the [[Posterior (anatomy)|posterior]] lobe of the [[pituitary gland]] which is part of the [[endocrine system]]. The posterior pituitary is not glandular as is the [[anterior pituitary]]. Instead, it is largely a collection of [[axonal projection]]s from the [[hypothalamus]] that terminate behind the anterior pituitary, and serve as a site for the secretion of [[neurohypophysial hormone]]s ([[oxytocin]] and [[vasopressin]]) directly into the blood.<ref name="NHM-Neuroendocrine systems">{{cite book | vauthors = Malenka RC, Nestler EJ, Hyman SE | editor = Sydor A, Brown RY | title = Molecular Neuropharmacology: A Foundation for Clinical Neuroscience | year = 2009 | publisher = McGraw-Hill Medical | location = New York | isbn = 9780071481274 | pages = 246, 248–259 | edition = 2nd | chapter = Chapter 10: Neural and Neuroendocrine Control of the Internal Milieu | quote = <br />•The hypothalamic–neurohypophyseal system secretes two peptide hormones directly into the blood, vasopressin and oxytocin.&nbsp;...<br />•The hypothalamic–pituitary–adrenal (HPA) axis. It comprises corticotropin-releasing factor (CRF), released by the hypothalamus; adrenocorticotropic hormone (ACTH), released by the anterior pituitary; and glucocorticoids, released by the adrenal cortex.<br />•The hypothalamic–pituitary–thyroid axis consists of hypothalamic thyrotropin-releasing hormone (TRH); the anterior pituitary hormone thyroid–stimulating hormone (TSH); and the thyroid hormones T₃ and T₄.<br />•The hypothalamic–pituitary–gonadal axis comprises hypothalamic gonadotropin–releasing hormone (GnRH), the anterior pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonadal steroids.}}</ref> The '''hypothalamic–neurohypophyseal system'''<!--term redirects here, bolded per MOS:BOLD--> is composed of the hypothalamus (the [[paraventricular nucleus]] and [[supraoptic nucleus]]), posterior pituitary, and these axonal projections.<ref name="NHM-Neuroendocrine systems" />

 

==Structure==

 

Classification of the posterior pituitary varies, but most sources include the two regions below:

 

The [[median eminence]] is only occasionally included as part of the posterior pituitary. Other sources specifically exclude it from the pituitary.<ref>{{MeshName|Median+eminence}}</ref>

 

===Hormone secretion===

 

{| class="wikitable"

|-

| [[Oxytocin]]

| [[Uterus]], [[mammary gland]]s

| [[Uterine contraction]]s; [[lactation]]

|-

| [[Vasopressin]]

| VP, AVP, ADH

| [[Kidney]]s and [[arteriole]]s

==Clinical significance==

Insufficient secretion of [[vasopressin]] underlies [[diabetes insipidus]], a condition in which the body loses the capacity to concentrate urine. Affected individuals excrete as much as 20 liters of dilute urine per day. Oversecretion of vasopressin causes the [[syndrome of inappropriate antidiuretic hormone]] (SIADH).

==See also==

{{Anatomy-terms}}

 

==References==

Image:Gray1180.png|The posterior pituitary comprises the posterior lobe of the pituitary gland.

</gallery>

==External links==

* [http://www.pituitary.org www.pituitary.org]&nbsp;— The Pituitary Network Association

{{Endocrine system anatomy}}

{{Diencephalon}}

 

{{DEFAULTSORT:Posterior Pituitary}}

[[Category:Neuroendocrinology]]