anterior pituitary gland

(noun)

A major organ of the endocrine system that regulates several physiological processes including stress, growth, reproduction, and lactation.

Examples of anterior pituitary gland in the following topics:

  • 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.

  • 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.
    • The fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary.
    • The anterior pituitary is composed of multiple parts:
    • 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).

  • 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.

  • 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

    • A collection of endocrine glands makes up the endocrine system: the pituitary (anterior and posterior lobes), thyroid, parathyroid, adrenal (cortex and medulla), pancreas and gonads.
    • The pituitary gland consists of two major regions, the anterior pituitary gland (adenohypophysis) and the posterior pituitary gland (neurohypophysis).
    • These hormones are released into a capillary network that supplies the anterior pituitary.
    • The hormones then diffuse from this secondary plexus into the anterior pituitary, where they initiate the production of specific hormones by the anterior pituitary.
    • Differentiate among the types of endocrine glands (pituitary [posterior pituitary, anterior pituitary], thyroid, parathyroid, adrenal, and pancreas) in the endocrine system

  • The Posterior Pituitary

    • 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 derived from the hypothalamus and is distinct from the more fleshy, vascularized anterior lobe.
    • The posterior pituitary is composed of two parts:
    • Identify the location of the posterior pituitary and the hormones associated with it

  • 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.

  • Overview of the Thyroid Gland

    • The thyroid gland, in the anterior neck, controls body metabolism, protein synthesis, and a body's responsiveness to other hormones.
    • In vertebrates, the thyroid gland is one of the largest endocrine glands.
    • The hormonal output from the thyroid is regulated by thyroid-stimulating hormone (TSH) produced by the anterior pituitary, which itself is regulated by thyrotropin-releasing hormone (TRH) produced by the hypothalamus .
    • The organ is situated on the anterior side of the neck, lying against and around the larynx and trachea, reaching posteriorly the oesophagus and carotid sheath.
    • Thyroid function is regulated by the actions of the hypothalamus and pituitary gland.

  • The Stress Response

    • The body's stress response is mediated by the sympathetic nervous system and the hypothalmic-pituitary-adrenal (HPA) axis.
    • The body's stress response is mediated by the interplay between the sympathetic nervous system (SNS) and the hypothalmic-pituitary-adrenal (HPA) axis.
    • A complex interaction of direct influences and indirect feedback mechanisms among the SNS, the hypothalmus, the pituitary gland and the adrenal glands contributes to the neuroendocrine regulation involved in reactions to stress.
    • These two hormones regulate the anterior lobe of the pituitary gland and stimulate the release of adrenocorticotropic hormone (ACTH), also known as corticotropin.
    • CRH gets transported to the anterior pituitary through the circulatory system and vasopressin is transported by axonal transport to the anterior pituitary.

  • 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 .
    • Most of the hormones in the anterior pituitary are each part of an axis that is regulated by the hypothalamus.
    • 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.