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The posterior pituitary is not glandular as is the anterior pituitary. Instead, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary, and serve as a site for the secretion of neurohypophysial hormones ( oxytocin and vasopressin ) directly into the blood. [ 2 ]
The pituitary gland is divided into three lobes: the anterior pituitary, the intermediate pituitary lobe, and the posterior pituitary. The hypothalamus controls the anterior pituitary's hormone secretion by sending releasing factors, called tropic hormones , down the hypothalamo-hypophysial portal system. [ 3 ]
The process occurs as follows: in some hypothalamic cells there are osmoreceptors which respond to hyperosmolality in body fluids by signalling the posterior pituitary gland to secrete ADH. [6] This keeps serum sodium concentration – a proxy for solute concentration – at normal levels, prevents hypernatremia and turns off the osmoreceptors. [7]
Hyperpituitarism is a condition due to the primary hypersecretion of pituitary hormones; [3] [medical citation needed] it typically results from a pituitary adenoma.In children with hyperpituitarism, disruption of growth regulation is rare, either because of hormone hypersecretion or because of manifestations caused by local compression of the adenoma.
They may be mistaken for the much more common pituitary adenoma, as well as craniopharyngioma and meningioma. Symptoms from the mass effect of the tumor usually include vision disorders, and less often headaches, hypopituitarism (decreased function of the pituitary gland), fatigue, and decreased libido.
Autoimmune hypophysitis can lead to deficiencies in one or more pituitary hormones, causing central diabetes insipidus if the posterior pituitary gland is affected as well as central adrenal insufficiency and central hypothyroidism if the anterior pituitary gland is affected. [1] The symptoms depend on what part of the pituitary is affected.
It is also known as neurohypophyseal diabetes insipidus, [2] [3] referring to the posterior pituitary (neurohypophysis), which receives vasopressin from the hypothalamus in the brain, via the hypothalamo-hypophyseal tract in the pituitary stalk. This condition has only polyuria in common with diabetes. Although not mutually exclusive, with most ...
Pituitary stalk interruption syndrome (PSIS) is a congenital disorder characterised by the triad of an absent or exceedingly thin pituitary stalk, an ectopic or absent posterior pituitary and/or absent or hypoplastic anterior pituitary. [1] [2]