pituitary adj

1 of or relating to the pituitary gland; "pituitary hormone"

2 having abnormal size with overgrown extremities resulting from abnormal pituitary secretion; "a protruding acromegalic jaw"; "a pituitary dwarf" [syn: acromegalic] n : the master gland of the endocrine system; located at the base of the brain [syn: pituitary gland, pituitary body, hypophysis]

English

Adjective

1. Of or relating to the pituitary gland.

Noun

1. The pituitary gland.
2. An extract from the pituitary gland.

Translations

The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid bone in the middle cranial fossa at the base of the brain.

The pituitary gland secretes hormones regulating homeostasis, including trophic hormones that stimulate other endocrine glands. It is functionally connected to the hypothalamus by the median eminence.

The hypophysis is also the top cell of the suspensor in a dicot embryo, which will differentiate to form part of the root cap.

Sections

Located at the base of the brain, the pituitary is functionally linked to the hypothalamus. It is composed of two lobes: the adenohypophysis and neurohypophysis. The adenohypophysis, also referred to as the anterior pituitary is divided into anatomical regions known as the pars tuberalis, pars intermedia, and pars distalis. The neurohypophysis, also referred to as the posterior pituitary. The pituitary is functionally linked to the hypothalamus by the pituitary stalk, whereby hypothalamic releasing factors are released and in turn stimulate the release of pituitary hormones.

Anterior pituitary (Adenohypophysis)

main Anterior pituitary

The anterior pituitary anatomical regions synthesizes and secretes important endocrine hormones, such as ACTH, TSH, prolactin, growth hormone, endorphins, FSH, and LH. These hormones are released from the anterior pituitary under the influence of hypothalamic. The hypothalamic hormones travel to the anterior lobe by way of a special capillary system, called the hypothalamic-hypophyseal portal system.

Posterior pituitary (Neurohypophysis)

The hormones secreted by the posterior pituitary are

• Oxytocin, where the majority is released from the paraventricular nucleus in the hypothalamus
• Antidiuretic hormone (ADH, also known as vasopressin and AVP, arginine vasopressin), the majority of which is released from the supraoptic nucleus in the hypothalamus

Oxytocin is the only pituitary hormone to create a positive feedback loop. For example, uterine contractions stimulate the release of oxytocin from the posterior pituitary, which in turn increases uterine contractions. This positive feedback loop continues until the baby is born.

Intermediate lobe

There is also an intermediate lobe in many animals. For instance in fish it is believed to control physiological colour change. In adult humans it is just a thin layer of cells between the anterior and posterior pituitary. The intermediate lobe produces melanocyte-stimulating hormone (MSH), although this function is often (imprecisely) attributed to the anterior pituitary.

Functions

The pituitary hormones help control some of the following body processes:

• Growth
• Blood pressure
• Some aspects of pregnancy and childbirth including stimulation of uterine contractions during childbirth
• Breast milk production
• Sex organ functions in both women and men
• Thyroid gland function
• The conversion of food into energy (metabolism)
• Water and osmolarity regulation in the body

Pathology

Disorders involving the pituitary gland include:

Additional images

See also

• Head and neck anatomy

References

External links

• The Pituitary Gland, from the UMM Endocrinology Health Guide
• Oklamoma State, Endocrine System
• Pituitary apoplexy mimicking pituitary abscess http://www.ispub.com/ostia/index.php?xmlPrinter=true&xmlFilePath=journals/ijns/vol4n1/pituitary.xml