pituitary gland

(noun)

An endocrine gland, about the size of a pea, that sits in a small, bony cavity at the base of the brain whose secretions control the other endocrine glands and influence growth, metabolism, and maturation.

Related Terms

Examples of pituitary gland in the following topics:

  • Control of the Pituitary Gland by the Hypothalamus

    • The pituitary gland consists of the anterior pituitary and the posterior pituitary.
    • The pituitary gland consists of two components: the anterior pituitary and the posterior pituitary, and is functionally linked to the hypothalamus by the pituitary stalk (also named the infundibular stem, or simply the infundibulum).
    • Whilst the pituitary gland is known as the master endocrine gland, both of the lobes are under the control of the hypothalamus: the anterior pituitary receives its signals from the parvocellular neurons, and the posterior pituitary receives its signals from magnocellular neurons.
    • The posterior lobe of the pituitary gland develops as an extension of the hypothalamus.
    • The anterior and posterior lobes of the pituitary (hypophysis) gland are shown.

  • Overview of the Pituitary Gland

    • The pituitary gland is connected to the hypothalamus and secretes nine hormones that regulate body homeostasis.
    • The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea.
    • The pituitary gland secretes hormones that regulate homeostasis.
    • The pituitary gland is divided into two parts, the anterior pituitary and the posterior pituitary.
    • In this image, the pituitary gland is referred to by its other name, the hypophysis.

  • The Posterior Pituitary

    • The posterior pituitary secretes two important endocrine hormones—oxytocin and antidiuretic hormone.
    • The posterior pituitary (or neurohypophysis) comprises the posterior lobe of the pituitary gland and is part of the endocrine system.
    • Despite its name, the posterior pituitary gland is not a gland; rather, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary gland.
    • The posterior pituitary is composed of two parts:
    • Identify the location of the posterior pituitary and the hormones associated with it

  • Control of Thyroid Hormone Release

    • The production of thyroxine and triiodothyronine is regulated by thyroid-stimulating hormone (TSH) that is released from the anterior pituitary.
    • The production of thyroxine (T4) and triiodothyronine (T3) is primarily regulated by thyroid-stimulating hormone (TSH) that is released from the anterior pituitary gland.
    • Thyroid hormones also provide negative feedback to the hypothalamus and anterior pituitary gland.
    • Thyroid hormones are produced from the thyroid under the influence of thyroid-stimulating hormone (TSH) from the anterior pituitary gland, which is itself under the control of thyroptropin-releasing hormone (TRH) secreted by the hypothalamus.

  • Hormonal Regulation of the Male Reproductive System

    • However, it is known that initiation of spermatogenesis occurs at puberty due to the interaction of the hypothalamus, pituitary gland, and Leydig cells.
    • If the pituitary gland is removed, spermatogenesis can still be initiated by follicle-stimulating hormone (FSH) and testosterone.
    • Gonadotropin Releasing Hormone (GnRH) is mainly made in the preoptic area of the hypothalamus from where it travels to the pituitary gland.
    • Follicle Stimulating Hormone is released by the anterior pituitary gland.
    • Luteinizing Hormone is released by the anterior pituitary gland.

  • Overview of Endocrine Glands

    • The pituitary gland (hypophysis) is found in the inferior part of the brain, attached to the bottom of the hypothalamus by a slender stalk called the infundibulum.
    • The pituitary gland consists of two major regions, the anterior pituitary gland (adenohypophysis) and the posterior pituitary gland (neurohypophysis).
    • The hypothalamus also controls the glandular secretion of the pituitary gland.
    • There are four parathyroid glands, all located on the thyroid gland.
    • Differentiate among the types of endocrine glands (pituitary [posterior pituitary, anterior pituitary], thyroid, parathyroid, adrenal, and pancreas) in the endocrine system

  • The Anterior Pituitary

    • A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis) is the glandular, anterior lobe of the pituitary gland.
    • Its regulatory functions are achieved through the secretion of various peptide hormones that act on target organs including the adrenal gland, liver, bone, thyroid gland, and gonads.
    • Prolactin is a polypeptide hormone whose target is the ovaries and mammary glands.
    • Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the hypothalamus.
    • At this site, these neurons can release substances into the small blood vessels that travel directly to the anterior pituitary gland (the hypothalamo-hypophysial portal vessels).

  • Pituitary Gland Disorders

    • Disorders of pituitary gland can affect hormones which regulate growth and activity of other glands in the body.
    • The pituitary is a "small, pea-sized gland" located at the base of the brain .
    • In response to the releasing hormone rate, the anterior pituitary produces its hormones (TSH, ACTH, LH, FSH, GH) that stimulate effector hormone glands in the body, although prolactin acts directly on the breast gland.
    • Pituitary adenoma affects hormones which regulate growth and the activity of other glands in the body.
    • However, with an abnormal growth or tumor in the master gland, the pituitary adenomas do not spread to other body parts and are not cancerous.

  • Adrenal Gland Disorders

    • Adrenal insufficiency can also occur when the hypothalamus or the pituitary gland, both located at the base of the skull, does not make adequate amounts of the hormones that assist in regulating adrenal function.
    • This is called secondary adrenal insufficiency and is caused by lack of production of adrenocorticotropic hormone (ACTH) in the pituitary gland or lack of corticotropin-releasing hormone (CRH) in the hypothalamus.
    • Secondary adrenal insufficiency is caused by impairment of the pituitary gland or hypothalamus.
    • Other causes are a pituitary adenoma or microadenoma, hypothalamic tumor (surgical removal of a pituitary tumor can also suppress production of ACTH and lead to adrenal deficiency), and Sheehan's syndrome, which is associated with impairment of only the pituitary gland.
    • An example of second adrenal insufficiency syndrome can be caused by craniopharyngioma which is a benign tumor that can damage the pituitary gland causing the adrenal glands not to function.

  • Overview of the Endocrine System

    • The endocrine system is a system of ductless glands that secrete hormones—chemical messengers that are carried for long distances.
    • For example, the pineal gland, located at the base of the brain, secretes the hormone melatonin, responsible for regulating sleep patterns.
    • The endocrine system is in contrast to the exocrine system, which features ducted glands that secrete substances onto an epithelial surface; for example, a sweat gland.
    • The major endocrine glands include the pituitary, pineal, ovaries, testes, thyroid, hypothalamus and adrenal glands, additionally other tissues such as the kidney and liver also display secondary adrenal functions.
    • The endocrine systems found in the head and neck include the hypothalamus, pineal, pituitary and thyroid glands.