Pituitary gland

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gland

 [gland]
an aggregation of cells specialized to secrete or excrete materials not related to their ordinary metabolic needs. Glands are divided into two main groups, endocrine and exocrine. adj., adj glan´dular.

The endocrine glands, or ductless glands, discharge their secretions (hormones) directly into the blood; they include the adrenal, pituitary, thyroid, and parathyroid glands, the islands of Langerhans in the pancreas, the gonads, the thymus, and the pineal body. The exocrine glands discharge through ducts opening on an external or internal surface of the body; they include the salivary, sebaceous, and sweat glands, the liver, the gastric glands, the pancreas, the intestinal, mammary, and lacrimal glands, and the prostate. The lymph nodes are sometimes called lymph glands but are not glands in the usual sense.
Classification of glands according to mode of secretion. From Applegate, 2000.
acinous gland one made up of one or more acini (oval or spherical sacs).
adrenal gland see adrenal gland.
apocrine gland one whose discharged secretion contains part of the secreting cells.
areolar g's Montgomery's glands.
axillary g's lymph nodes in the axilla.
Bartholin g's two small mucus-secreting glands, one on each side in the lower pole of the labium majus and connected to the surface by a duct lined with transitional cells, which opens just external to the hymenal ring. Their exact function is not clear but they are believed to secrete mucus to moisten the vestibule during sexual excitement. Called also major vestibular glands.
Bowman's g's olfactory glands.
bronchial g's seromucous glands in the mucosa and submucosa of the bronchial walls.
Brunner's g's glands in the submucosa of the duodenum that secrete intestinal juice; called also duodenal glands.
buccal g's seromucous glands on the inner surface of the cheeks; called also genal glands.
bulbocavernous g's (bulbourethral g's) two glands embedded in the substance of the sphincter of the male urethra, posterior to the membranous part of the urethra; their secretion lubricates the urethra; called also Cowper's glands.
cardiac g's mucus-secreting glands of the cardiac part (cardia) of the stomach.
celiac g's lymph nodes anterior to the abdominal aorta.
ceruminous g's cerumin-secreting glands in the skin of the external auditory canal.
cervical g's
1. the lymph nodes of the neck.
2. compound clefts in the wall of the uterine cervix.
ciliary g's sweat glands that have become arrested in their development, situated at the edges of the eyelids; called also Moll's glands.
circumanal g's specialized sweat and sebaceous glands around the anus; called also Gay's glands.
Cobelli's g's mucous glands in the esophageal mucosa just above the cardia.
coccygeal gland glomus coccygeum.
compound gland one made up of a number of smaller units whose excretory ducts combine to form ducts of progressively higher order.
Cowper's g's bulbourethral glands.
ductless g's endocrine glands.
duodenal g's Brunner's glands.
Ebner's g's serous glands at the back of the tongue near the taste buds.
eccrine gland one of the ordinary or simple sweat glands, which are of the merocrine type.
endocrine g's see endocrine glands.
exocrine g's glands that discharge their secretions through ducts opening on internal or external surfaces of the body; see gland.
fundic g's (fundus g's) numerous tubular glands in the mucosa of the fundus and body of the stomach that contain the cells that produce acid and pepsin.
gastric g's the secreting glands of the stomach, including the fundic, cardiac, and pyloric glands.
Gay's g's circumanal glands.
genal g's buccal glands.
glossopalatine g's mucous glands at the posterior end of the smaller sublingual glands.
haversian g's synovial villi.
holocrine gland one whose discharged secretion contains the entire secreting cells.
intestinal g's straight tubular glands in the mucous membrane of the intestines, in the small intestine opening between the bases of the villi, and containing argentaffin cells. Called also crypts or glands of Lieberkühn.
jugular gland a lymph node behind the clavicular insertion of the sternocleidomastoid muscle.
Krause's gland an accessory lacrimal gland deep in the conjunctival connective tissue, mainly near the upper fornix.
lacrimal g's the glands that secrete tears; see also lacrimal apparatus.
g's of Lieberkühn intestinal glands.
lingual g's the seromucous glands on the surface of the tongue.
lingual g's, anterior seromucous glands near the apex of the tongue.
Littre's g's
2. the male urethral glands.
lymph gland lymph node.
major vestibular g's Bartholin glands.
mammary gland a specialized gland of the skin of female mammals, which secretes milk for the nourishment of their young; it exists in a rudimentary state in the male. See also breast.
meibomian g's sebaceous follicles between the cartilage and conjunctiva of the eyelids. Called also tarsal glands.
merocrine gland one whose discharged secretion contains no part of the secreting cells.
mixed g's
1. seromucous glands.
2. glands that have both exocrine and endocrine portions.
Moll's g's ciliary glands.
Montgomery's g's sebaceous glands in the mammary areola; called also areolar glands.
mucous g's glands that secrete mucus.
olfactory g's small mucous glands in the olfactory mucosa; called also Bowman's glands.
parathyroid g's see parathyroid glands.
parotid g's see parotid glands.
peptic g's gastric glands that secrete pepsin.
pineal gland pineal body.
pituitary gland see pituitary gland.
preputial g's small sebaceous glands of the corona of the penis and the inner surface of the prepuce, which secrete smegma; called also Littre's glands and Tyson's glands.
prostate gland prostate.
pyloric g's the mucin-secreting glands of the pyloric part of the stomach.
salivary g's see salivary glands.
sebaceous gland a type of holocrine gland of the corium that secretes an oily material (sebum) into the hair follicles.
Glands: The relationship of the hair follicle, eccrine and apocrine sweat glands and sebaceous glands. From Copstead, 1995.
sentinel gland an enlarged lymph node, considered to be pathognomonic of some pathologic condition elsewhere.
seromucous g's glands that are both serous and mucous.
serous gland a gland that secretes a watery albuminous material, commonly but not always containing enzymes.
sex gland (sexual gland) gonad.
simple gland one with a nonbranching duct.
Skene's g's the largest of the female urethral glands, which open into the urethral orifice; they are regarded as homologous with the prostate. Called also paraurethral ducts.
solitary g's solitary follicles.
sublingual gland a salivary gland on either side under the tongue.
submandibular gland (submaxillary gland) a salivary gland on the inner side of each ramus of the mandible.
sudoriferous gland (sudoriparous gland) sweat gland.
suprarenal gland adrenal gland.
sweat gland see sweat gland.
target gland any gland affected by a secretion or other stimulus from another gland, such as those affected by the secretions of the pituitary gland.
tarsal g's meibomian glands.
thymus gland thymus.
thyroid gland see thyroid gland.
tubular gland any gland made up of or containing a tubule or tubules.
Tyson's g's preputial glands.
unicellular gland a single cell that functions as a gland, e.g., a goblet cell.
urethral g's mucous glands in the wall of the urethra; in the male, called also Littre's glands.
uterine g's simple tubular glands found throughout the thickness and extent of the endometrium; they become enlarged during the premenstrual period.
vesical g's mucous glands sometimes found in the wall of the urinary bladder, especially in the area of the trigone.
vulvovaginal g's Bartholin's glands.
Waldeyer's g's glands in the attached edge of the eyelid.
Weber's g's the tubular mucous glands of the tongue.

pituitary

 [pĭ-tu´ĭ-tar″e]
1. pertaining to the pituitary gland.
3. a preparation of the pituitary glands of animals, used therapeutically.
pituitary gland an endocrine gland located at the base of the brain in a small recess of the sphenoid bone called the sella turcica. It is attached by the hypophyseal stalk to the hypothalamus and is divided into an anterior lobe (the adenohypophysis) and a posterior lobe (the neurohypophysis), which differ in embryological function and origin. Called also hypophysis.

The adenohypophysis originates from epithelial tissue. The adenohypophysis secretes six important hormones: growth hormone, thyroid-stimulating hormone or thyrotropin, adrenocorticotropic hormone or corticotropin, prolactin, follicle-stimulating hormone, and luteinizing hormone. Most of these hormones are tropic hormones, which regulate the growth, development, and proper functioning of other endocrine glands and are of vital importance to the growth, maturation, and reproduction of the individual. Secretion of the anterior pituitary hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus. Information gathered by the nervous system about the well-being of an individual is collected in the hypothalamus and used to control the secretion of hormones by the pituitary gland. The hypothalamic releasing and inhibiting hormones are transported to the pituitary gland by way of the hypothalamic-hypophyseal portal system in which the hypothalamic venules connect with the capillaries of the anterior pituitary.

The neurohypophysis originates from neural tissue; it stores and secretes two hormones, oxytocin and vasopressin (antidiuretic hormone). These hormones are synthesized in the cell bodies of neurons located in the hypothalamus and transported along the axons to the terminals located in the neurohypophysis and are released in response to neural stimulation.

Surgical removal of part or all of the pituitary gland is called hypophysectomy and is usually done for treatment of a pituitary tumor. Because of its influence on the adrenal cortex and other endocrine glands, removal of the pituitary gland has widespread effects on the body. See hypophysectomy.
The pituitary gland and its relationship to the hypothalamus.
posterior pituitary neurohypophysis.

pi·tu·i·tar·y gland

[TA]
an unpaired compound gland suspended from the base of the hypothalamus by a short extension of the infundibulum, the infundibular or pituitary stalk. The hypophysis consists of two major divisions. The first, the neurohypophysis, comprises the infundibulum and its bulbous termination, the neural part or infundibular process (posterior lobe), which is composed of neuroglialike pituicytes, blood vessels, and unmyelinated nerve fibers of the hypothalamohypophysial tract. The cell bodies of these axons reside in the supraoptic and paraventricular nuclei of the hypothalamus. These fibers convey to the lobe for storage and release the neurosecretory hormones oxytocin and antidiuretic hormone. The second division, the adenohypophysis, comprises the larger distal part, a sleevelike extension of this lobe (infundibular part) that invests the infundibular stalk, and a thin intermediate part (poorly developed in humans) between the anterior and posterior lobes; the anterior lobe consists of cords of cells of several different types interspersed on the secondary capillary bed of the hypothalamohypophysial portal system. Secretion of somatotropins, prolactin, thyroid-stimulating hormone, gonadotropins, adrenal corticotropin, and other related peptides in the adenohypophysis is regulated by releasing and inhibiting factors elaborated by neurons in the hypothalamus that are taken up by a primary plexus of capillaries in the median eminence and transported through portal vessels in the infundibular part and infundibular stem to a secondary plexus of capillaries in the distal part.

pituitary gland

n.
A small oval endocrine gland attached to the base of the vertebrate brain and consisting of an anterior and a posterior lobe, the secretions of which control the other endocrine glands and influence growth, metabolism, and maturation. Also called hypophysis, pituitary body.

pituitary gland

Etymology: L, pituita, phlegm
an endocrine gland suspended beneath the brain in the pituitary fossa of the sphenoid bone, supplying numerous hormones that govern many vital processes. It is divided into an anterior adenohypophysis and a smaller posterior neurohypophysis. The anterior lobe of the gland is composed of polygonal cells related to the production of seven hormones. The hormones, controlled by hypothalamic releasing factors, include growth hormone (somatotropin), prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and melanocyte-stimulating hormone. The posterior lobe is morphologically an extension of the hypothalamus and the source of vasopressin (antidiuretic hormone) and oxytocin. Vasopressin inhibits diuresis by promoting nephron water reabsorption and raises blood pressure. Oxytocin stimulates the contraction of smooth muscle, especially in the uterus. Also called hypophysis, hypophysis cerebri. See also adenohypophysis, neurohypophysis.

hy·poph·y·sis

(hī-pof'i-sis) [TA]
An unpaired compound gland suspended from the base of the hypothalamus by a short extension of the infundibulum, the infundibular or pituitary stalk. It consists of two major subdivisions: 1) the neurohypophysis and 2) the adenohypophysis, comprising the larger distal part.
See also: hypothalamus
Synonym(s): pituitary gland.
[G. an undergrowth]
Enlarge picture
PITUITARY GLAND: Hormones secreted by the anterior and posterior pituitary gland, along with target organs

pituitary gland

A small, gray, rounded gland that develops from ingrown oral epithelium (Rathke pouch) and is attached to the lower surface of the hypothalamus by the infundibular stalk. The Rathke pouch portion forms the anterior lobe and an intermediate area; the neural tissue of the infundibular stalk forms the posterior lobe. The pituitary gland averages 1.3 × 1.0 ×0.5 cm in size and weighs 0.55 to 0.6 g. Synonym: hypophysis; hypophysis cerebri See: illustration

Function

The pituitary is an endocrine gland secreting a number of hormones that regulate many bodily processes including growth, reproduction, and other metabolic activities. It is often referred to as the “master gland of the body.”

Hormones are secreted in the following lobes: Intermediate lobe: In cold-blooded animals, intermedin is secreted, influencing the activity of pigment cells (chromatophores) of fishes, amphibians, and reptiles. In warm-blooded animals, no effects are known.

Anterior lobe: Secretions here are the somatotropic, or growth hormone (STH or GH), which regulates cell division and protein synthesis for growth; adrenocorticotropic hormone (ACTH), which regulates functional activity of the adrenal cortex; thyrotropic hormone (TTH or TSH), which regulates functional activity of the thyroid gland; and prolactin, also called lactogenic hormone, which induces secretion of milk in the adult female. The gonadotropic hormones are as follows: in women, follicle-stimulating hormone (FSH) stimulates development of ovarian follicles and their secretion of estrogen; in men, it stimulates spermatogenesis in the testes. In women, luteinizing hormone (LH) stimulates ovulation and formation of the corpus luteum and its secretion of estrogen and progesterone. In men, LH also called interstitial cell-stimulation hormone (ICSH), stimulates testosterone secretion.

Posterior lobe: Hormones are secreted by the neurosecretory cells of the hypothalamus and pass through fibers of the supraopticohypophyseal tracts in the infundibular stalk to the neurohypophysis, where they are stored. Secretions here are oxytocin, which acts specifically on smooth muscle of the uterus, increasing tone and contractility, and antidiuretic hormone (ADH), which increases reabsorption of water by the kidney tubules. In large amounts, ADH also causes vasoconstriction, and is also called vasopressin.

Disorders

Hypersecretion of anterior lobe causes gigantism, acromegaly, and pituitary basophilism (Cushing disease). Hyposecretion of anterior lobe causes dwarfism, pituitary cachexia (Simmonds disease), Sheehan syndrome, acromicria, eunuchoidism, or hypogonadism. Posterior lobe deficiency or hypothalamic lesion causes diabetes insipidus. Anterior and posterior lobe deficiency and hypothalamic lesion cause Fröhlich syndrome (adiposogenital dystrophy) and pituitary obesity.

See also: gland

pituitary gland

The central controlling gland in the ENDOCRINE system. The pituitary is a pea-sized gland that hangs by a stalk from the underside of the brain and rests in a central bony hollow on the floor of the skull. The pituitary stalk emerges immediately under the HYPOTHALAMUS and there are numerous connections, both nervous and hormonal, between the hypothalamus and the gland. The pituitary releases many hormones that regulate and control the activities of other endocrine glands as well as many body processes. Hormonal feedback information from the various endocrine glands to the hypothalamus and the pituitary ensures that the pituitary is able to perform its control function effectively. See also ADRENOCORTICOTROPIC HORMONE, ANTIDIURETIC HORMONE, FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE, MELANOCYTE-STIMULATING HORMONE, OXYTOCIN, PROLACTIN, and THYROID-STIMULATING HORMONE,

Pituitary gland

The pituitary gland is sometimes referred to as the "master gland." As the most important of the endocrine glands (glands which release hormones directly into the bloodstream), it regulates and controls not only the activities of other endocrine glands but also many body processes.

pituitary gland

endocrine gland at the base of the brain, attached by the pituitary stalk carrying blood vessels and nerve fibres from the hypothalamus. See also anterior pituitary, posterior pituitary.

pi·tu·i·tar·y gland

(pi-tū'i-tar-ē gland) [TA]
Unpaired compound gland suspended from base of the hypothalamus by a short extension of infundibulum; the infundibular or pituitary stalk.
Synonym(s): hypophysis [TA] .

pituitary gland,

n an endocrine gland suspended beneath the brain in the pituitary fossa of the sphenoid bone. It produces a number of hormones essential for growth, metabolism, reproduction, and vascular control.