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Pituitary Gland: Anatomy

The pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland, also known as the hypophysis, is considered the “master endocrine gland” because it releases hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus, which is the primary regulator of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland. The pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland has 2 lobes: the anterior lobe Anterior lobe Cerebellum: Anatomy (the adenohypophysis) and the posterior lobe Posterior lobe Cerebellum: Anatomy (the neurohypophysis). Each lobe has its own regulation, set of secretory products, and feedback loops. Abnormalities in the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland can lead to a wide range of clinical conditions, some of which include hyperprolactinemia Hyperprolactinemia Hyperprolactinemia is defined as a condition of elevated levels of prolactin (PRL) hormone in the blood. The PRL hormone is secreted by the anterior pituitary gland and is responsible for breast development and lactation. The most common cause is PRL-secreting pituitary adenomas (prolactinomas). Hyperprolactinemia, acromegaly Acromegaly A condition caused by prolonged exposure to excessive human growth hormone in adults. It is characterized by bony enlargement of the face; lower jaw (prognathism); hands; feet; head; and thorax. The most common etiology is a growth hormone-secreting pituitary adenoma. Acromegaly and Gigantism, hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism or hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism, and central diabetes insipidus Diabetes Insipidus Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus.

Last updated: 5 Jul, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

The pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland is known as the “master endocrine gland.” This gland receives stimulatory input from the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus and secretes multiple different hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types, which target multiple different end organs and have wide-ranging effects throughout the body.

Location

  • Located in the sella turcica of the sphenoid bone Sphenoid bone An irregular unpaired bone situated at the skull base and wedged between the frontal, temporal, and occipital bones (frontal bone; temporal bone; occipital bone). Sphenoid bone consists of a median body and three pairs of processes resembling a bat with spread wings. The body is hollowed out in its inferior to form two large cavities (sphenoid sinus). Orbit and Extraocular Muscles: Anatomy
  • Just below the optic chiasm Optic Chiasm The x-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes. The Visual Pathway and Related Disorders
  • Connected to the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus by the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types stalk 
  • Lies outside the dura
Hypothalamic–pituitary complex

Hypothalamic– pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types complex:
The image shows the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland, made up of the anterior and posterior lobes, in relation to the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.

Image: “1806 The Hypothalamus-Pituitary Complex” by OpenStax College. License: CC BY 3.0

General structure

The pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland is divided into 2 primary components: 

  • Adenohypophysis (also known as the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
  • Neurohypophysis (also known as the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types)

The 2 halves function independently, as 2 separate glands, each with their own:

  • Embryologic origins
  • Anatomy
  • Connections to the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus
  • Regulatory controls
  • Functions

Development and Gross Anatomy

Development

Anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types:

  • Develops from outpocket of the oropharynx Oropharynx The middle portion of the pharynx that lies posterior to the mouth, inferior to the soft palate, and superior to the base of the tongue and epiglottis. It has a digestive function as food passes from the mouth into the oropharynx before entering esophagus. Pharynx: Anatomy (Rathke pouch)
  • Derived from oral ectoderm Ectoderm The outer of the three germ layers of an embryo. Gastrulation and Neurulation 

Posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types:

Gross anatomy

Major components of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland include:

  • Pars distalis: the bulk of the glandular portion/anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
  • Pars nervosa: the bulk of the neurosecretory portion/posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
  • Pars intermedia: a thin wedge separating the pars distalis from the pars nervosa
  • Pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types stalk:
    • Connects the pea-like lobes of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types (the pars distalis and the pars nervosa) to the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus
    • Consists of: 
Major subdivisions of the pituitary gland hypophysis

Major subdivisions of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland (hypophysis)

Image by Lecturio.

Connection to the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus

Adenohypophysis/anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types: via the hypothalamohypophyseal portal system (i.e., connected via the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment): 

  1. Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types are secreted by neurosecretory cells within the median eminence of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.
  2. Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types enter the primary capillary plexus of the portal system in the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.
  3. Primary capillary plexus drains into venules Venules The minute vessels that collect blood from the capillary plexuses and join together to form veins. Veins: Histology known as portal veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology.
  4. Portal veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology carry these regulatory hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types down the pars tuberalis to the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types.
  5. A secondary capillary plexus surrounds the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types cells.
  6. Regulatory hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types leave the portal system and act on their target cells in the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types.
  7. Cells within the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology their hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types into the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  8. Pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types are taken up by the surrounding veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology and travel to peripheral target organs.

Neurohypophysis/posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types: via the hypothalamohypophyseal tract (i.e., directly connected via the nerves)

  • Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types are synthesized within the hypothalamic nuclei:
    • Paraventricular nuclei: oxytocin
    • Supraoptic nuclei: antidiuretic hormone Antidiuretic hormone Antidiuretic hormones released by the neurohypophysis of all vertebrates (structure varies with species) to regulate water balance and osmolarity. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a cystine. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the kidney collecting ducts to increase water reabsorption, increase blood volume and blood pressure. Hypernatremia (ADH)
  • Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types travel down the neuronal axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology in the infundibulum Infundibulum Uterus, Cervix, and Fallopian Tubes: Anatomy in the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types stalk and are stored in the axon terminals.
  • Axon terminals are located within the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types.
  • When the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus is stimulated, the signal travels down the axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology in the hypothalamohypophyseal tract → triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of the stored hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types directly into circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment within the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
  • Note: The posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types can be thought of as an extension Extension Examination of the Upper Limbs of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.

Microscopic Anatomy

Adenohypophysis (anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types)

General characteristics:

  • Glandular portion of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
  • Consists of endocrine cells and dense capillary networks
  • Categorization Categorization Types of Variables:
    • The endocrine cells can be categorized as chromophils or chromophobes, based on staining characteristics. 
    • Specific cell types can be differentiated by immunocytochemical staining.
  • Endocrine cells get their stimulation from hypothalamic hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types secreted into the primary capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology of the hypothalamohypophyseal portal system.

Chromophils:

  • Basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation
    • Corticotropes: 
      • Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology adrenocorticotropic hormone Adrenocorticotropic hormone An anterior pituitary hormone that stimulates the adrenal cortex and its production of corticosteroids. Acth is a 39-amino acid polypeptide of which the n-terminal 24-amino acid segment is identical in all species and contains the adrenocorticotropic activity. Upon further tissue-specific processing, acth can yield alpha-msh and corticotropin-like intermediate lobe peptide (clip). Adrenal Hormones (ACTH) 
      • 15%–20% of endocrine cells
    • Thyrotropes: 
      • Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology thyroid-stimulating hormone Thyroid-stimulating hormone A glycoprotein hormone secreted by the adenohypophysis. Thyrotropin stimulates thyroid gland by increasing the iodide transport, synthesis and release of thyroid hormones (thyroxine and triiodothyronine). Thyroid Hormones (TSH)
      • 5% of endocrine cells
    • Gonadotropes: 
      • Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology luteinizing hormone ( LH LH A major gonadotropin secreted by the adenohypophysis. Luteinizing hormone regulates steroid production by the interstitial cells of the testis and the ovary. The preovulatory luteinizing hormone surge in females induces ovulation, and subsequent luteinization of the follicle. Luteinizing hormone consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity. Menstrual Cycle) and follicle-stimulating hormone ( FSH FSH A major gonadotropin secreted by the adenohypophysis. Follicle-stimulating hormone stimulates gametogenesis and the supporting cells such as the ovarian granulosa cells, the testicular sertoli cells, and leydig cells. Fsh consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity. Menstrual Cycle)
      • 10% of endocrine cells
  • Acidophils: 
    • Lactotropes: 
      • Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology prolactin Prolactin A lactogenic hormone secreted by the adenohypophysis. It is a polypeptide of approximately 23 kd. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Breasts: Anatomy
      • 15%–20% of endocrine cells 
    • Somatotropes: 
      • Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology growth hormone (GH)
      • 50% of endocrine cells

Chromophobes:

  • Cells that do not take up stain well
  • Function is unclear.
Microanatomy histology_of_pars_distalis_of_the_anterior_pituitary_with_chromophobes

Microanatomy of the pars distalis in the anterior lobe Anterior lobe Cerebellum: Anatomy of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland showing chromophobes, basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation, and acidophils

Image: “Microanatomy of the pars distalis showing chromophobes, basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation, and acidophils” by Mikael Häggström. License: CC0 1.0

Neurohypophysis (posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types)

The neurohypophysis is filled with the terminal axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology of neurosecretory cells, supporting cells known as pituicytes, and dense networks of fenestrated capillaries Fenestrated capillaries Wall contains multiple fenestrations, or “pores”, with continuous basal lamina. Capillaries: Histology.

  • Neurosecretory cells (nerve cells):
    • Cell bodies are within the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.
    • Unmyelinated axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology travel down the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types stalk.
    • Axon terminals are located within the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types.
  • Herring bodies: 
  • Pituicytes: 
    • Nerve cells similar to astrocytes Astrocytes A class of large neuroglial (macroglial) cells in the central nervous system – the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from ‘star’ cells) are irregularly shaped with many long processes, including those with ‘end feet’ which form the glial (limiting) membrane and directly and indirectly contribute to the blood-brain barrier. They regulate the extracellular ionic and chemical environment, and ‘reactive astrocytes’ (along with microglia) respond to injury. Nervous System: Histology found in the CNS
    • Supporting cells that wrap around the axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology and capillary vessels
    • Maintain the integrity of the blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier
    • Assist in regulating hormone release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology from the axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology

Vasculature

Arterial supply

  • Superior hypophyseal artery:
    • Supplies the primary capillary plexus in the median eminence of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus (forms the 1st part of the hypothalamohypophyseal portal system)
    • Originates from the internal carotid artery Internal carotid artery Branch of the common carotid artery which supplies the anterior part of the brain, the eye and its appendages, the forehead and nose. Carotid Arterial System: Anatomy
  • Trabecular artery: connects the superior and inferior hypophyseal arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology
  • Inferior hypophyseal artery: 
    • The major arterial supply for the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
    • Originates from the meningohypophyseal trunk (a branch of the internal carotid artery Internal carotid artery Branch of the common carotid artery which supplies the anterior part of the brain, the eye and its appendages, the forehead and nose. Carotid Arterial System: Anatomy)
    • Fenestrated capillaries Fenestrated capillaries Wall contains multiple fenestrations, or “pores”, with continuous basal lamina. Capillaries: Histology → allow for hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types secreted in the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types to easily enter systemic circulation Systemic circulation Circulation is the movement of blood throughout the body through one continuous circuit of blood vessels. Different organs have unique functions and, therefore, have different requirements, circulatory patterns, and regulatory mechanisms. Systemic and Special Circulations
    • Note: The anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types lacks a direct major arterial supply → gets its supply from the portal system capillary network

Venous drainage

Both the anterior and posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types drain into:

  • Hypophyseal veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology, which drain into:
    • Cavernous sinus → petrosal sinuses → internal jugular veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology

Functions

The pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland’s primary function is to secrete a variety of regulatory hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types.

Anterior pituitary hormones Anterior pituitary hormones Hormones secreted by the adenohypophysis. Structurally, they include polypeptide, protein, and glycoprotein molecules. Hypothalamic and Pituitary Hormones

Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types secreted by the anterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment many of the other major endocrine glands Endocrine glands Ductless glands that secrete hormones directly into the blood circulation. These hormones influence the metabolism and other functions of cells in the body. Glandular Epithelium: Histology in the body. Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types are part of complex regulatory systems known as “axes.” These axes are summarized in the table below.

Table: Hypothalamic-pituitary axis Axis The second cervical vertebra. Vertebral Column: Anatomy (HPA) hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types and targets
Hypothalamic hormone Pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types target cell Pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types hormone Target organ End effects
Corticotropin-releasing hormone Corticotropin-releasing hormone A peptide of about 41 amino acids that stimulates the release of adrenocorticotropic hormone. Crh is synthesized by neurons in the paraventricular nucleus of the hypothalamus. After being released into the pituitary portal circulation, crh stimulates the release of acth from the pituitary gland. Crh can also be synthesized in other tissues, such as placenta; adrenal medulla; and testis. Hypothalamic and Pituitary Hormones (CRH) Corticotropes ACTH Adrenal cortex Adrenal Cortex The outer layer of the adrenal gland. It is derived from mesoderm and comprised of three zones (outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis) with each producing various steroids preferentially, such as aldosterone; hydrocortisone; dehydroepiandrosterone; and androstenedione. Adrenal cortex function is regulated by pituitary adrenocorticotropin. Adrenal Glands: Anatomy Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of corticosteroids Corticosteroids Chorioretinitis
Thyrotropin-releasing hormone Thyrotropin-releasing hormone A tripeptide that stimulates the release of thyrotropin and prolactin. It is synthesized by the neurons in the paraventricular nucleus of the hypothalamus. After being released into the pituitary portal circulation, TRH stimulates the release of TSH and PRL from the anterior pituitary gland. Hypothalamic and Pituitary Hormones (TRH) Thyrotropes TSH Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy gland Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of thyroid hormones Thyroid hormones The 2 primary thyroid hormones are triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized and secreted by the thyroid, and they are responsible for stimulating metabolism in most cells of the body. Their secretion is regulated primarily by thyroid-stimulating hormone (TSH), which is produced by the pituitary gland. Thyroid Hormones
Gonadotropin-releasing hormone Gonadotropin-releasing hormone A decapeptide that stimulates the synthesis and secretion of both pituitary gonadotropins, luteinizing hormone and follicle stimulating hormone. Gnrh is produced by neurons in the septum preoptic area of the hypothalamus and released into the pituitary portal blood, leading to stimulation of gonadotrophs in the anterior pituitary gland. Puberty (GnRH) Gonadotropes FSH FSH A major gonadotropin secreted by the adenohypophysis. Follicle-stimulating hormone stimulates gametogenesis and the supporting cells such as the ovarian granulosa cells, the testicular sertoli cells, and leydig cells. Fsh consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity. Menstrual Cycle
  • Gonads Gonads The gamete-producing glands, ovary or testis. Hormones: Overview and Types
  • Ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries: Anatomy
  • Testes Testes Gonadal Hormones
Development of ovarian follicles and sperm production
LH LH A major gonadotropin secreted by the adenohypophysis. Luteinizing hormone regulates steroid production by the interstitial cells of the testis and the ovary. The preovulatory luteinizing hormone surge in females induces ovulation, and subsequent luteinization of the follicle. Luteinizing hormone consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity. Menstrual Cycle
  • Gonads Gonads The gamete-producing glands, ovary or testis. Hormones: Overview and Types
  • Ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries: Anatomy
  • Testes Testes Gonadal Hormones
  • Androgen production (both sexes)
  • Stimulates ovulation Ovulation The discharge of an ovum from a rupturing follicle in the ovary. Menstrual Cycle (females)
Growth hormone–releasing hormone ( GHRH GHRH A peptide of 44 amino acids in most species that stimulates the release and synthesis of growth hormone. GHRF (or GRF) is synthesized by neurons in the arcuate nucleus of the hypothalamus. After being released into the pituitary portal circulation, GHRF stimulates gh release by the somatotrophs in the pituitary gland. Hypothalamic and Pituitary Hormones) Somatotropes GH Many organs Anabolic effects
Somatostatin Somatostatin A 14-amino acid peptide named for its ability to inhibit pituitary growth hormone release, also called somatotropin release-inhibiting factor. It is expressed in the central and peripheral nervous systems, the gut, and other organs. SRIF can also inhibit the release of thyroid-stimulating hormone; prolactin; insulin; and glucagon besides acting as a neurotransmitter and neuromodulator. In a number of species including humans, there is an additional form of somatostatin, srif-28 with a 14-amino acid extension at the n-terminal. Gastrointestinal Secretions (inhibitor) Somatotropes GH (inhibited) Many organs Anabolic effects inhibited with somatostatin Somatostatin A 14-amino acid peptide named for its ability to inhibit pituitary growth hormone release, also called somatotropin release-inhibiting factor. It is expressed in the central and peripheral nervous systems, the gut, and other organs. SRIF can also inhibit the release of thyroid-stimulating hormone; prolactin; insulin; and glucagon besides acting as a neurotransmitter and neuromodulator. In a number of species including humans, there is an additional form of somatostatin, srif-28 with a 14-amino acid extension at the n-terminal. Gastrointestinal Secretions
Dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS (inhibitor) Lactotropes Prolactin Prolactin A lactogenic hormone secreted by the adenohypophysis. It is a polypeptide of approximately 23 kd. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Breasts: Anatomy (inhibited) Mammary glands Milk production inhibited with dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS

Posterior pituitary hormones Posterior pituitary hormones Hormones released from the neurohypophysis. They include a number of peptides which are formed in the neurons in the hypothalamus, bound to neurophysins, and stored in the nerve terminals in the posterior pituitary. Upon stimulation, these peptides are released into the hypophyseal portal vessel blood. Hypothalamic and Pituitary Hormones

The 2 major posterior pituitary hormones Posterior pituitary hormones Hormones released from the neurohypophysis. They include a number of peptides which are formed in the neurons in the hypothalamus, bound to neurophysins, and stored in the nerve terminals in the posterior pituitary. Upon stimulation, these peptides are released into the hypophyseal portal vessel blood. Hypothalamic and Pituitary Hormones are ADH and oxytocin, which are not involved in regulatory axes the way the anterior pituitary hormones Anterior pituitary hormones Hormones secreted by the adenohypophysis. Structurally, they include polypeptide, protein, and glycoprotein molecules. Hypothalamic and Pituitary Hormones are. These hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types act directly on end target organs.

Table: Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types of posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types
Hormone Synthesis Synthesis Polymerase Chain Reaction (PCR) Target organ Function
Antidiuretic hormone Antidiuretic hormone Antidiuretic hormones released by the neurohypophysis of all vertebrates (structure varies with species) to regulate water balance and osmolarity. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a cystine. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the kidney collecting ducts to increase water reabsorption, increase blood volume and blood pressure. Hypernatremia (ADH) Supraoptic nuclei of hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus Kidney
Oxytocin Paraventricular nuclei of hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus Breast Stimulates milk ejection Milk ejection Expulsion of milk from the mammary alveolar lumen, which is surrounded by a layer of milk-secreting epithelial cells and a network of myoepithelial cells. Contraction of the myoepithelial cells is regulated by neuroendocrine signals. Breastfeeding during lactation Lactation The processes of milk secretion by the maternal mammary glands after parturition. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including estradiol; progesterone; prolactin; and oxytocin. Breastfeeding
Uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy Stimulates uterine contractions during labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor

Clinical Relevance

  • Hypopituitarism Hypopituitarism Hypopituitarism is a condition characterized by pituitary hormone deficiency. This condition primarily results from a disease of the pituitary gland, but it may arise from hypothalamic dysfunction. Pituitary tumors are one of the most common causes. The majority of cases affect the anterior pituitary lobe (adenohypophysis), which accounts for 80% of the gland. Hypopituitarism: condition characterized by a deficiency of all the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types. Because these hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types regulate multiple different organs, the effects of pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types hypofunction are multisystemic. Causes include pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types masses, congenital Congenital Chorioretinitis syndromes, trauma, infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, and vascular damage. Diagnosis is via a combination of clinical findings, hormone levels, provocation tests, and brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification imaging. Treatment is hormonal replacement and addressing the underlying etiology.
  • Pituitary adenoma Pituitary adenoma Pituitary adenomas are tumors that develop within the anterior lobe of the pituitary gland. Non-functioning or non-secretory adenomas do not secrete hormones but can compress surrounding pituitary tissue, leading to hypopituitarism. Secretory adenomas secrete various hormones depending on the cell type from which they evolved, leading to hyperpituitarism. Pituitary Adenomas: tumors that develop within the anterior lobe Anterior lobe Cerebellum: Anatomy of the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland. Pituitary adenomas Pituitary adenomas Pituitary adenomas are tumors that develop within the anterior lobe of the pituitary gland. Non-functioning or non-secretory adenomas do not secrete hormones but can compress surrounding pituitary tissue, leading to hypopituitarism. Secretory adenomas secrete various hormones depending on the cell type from which they evolved, leading to hyperpituitarism. Pituitary Adenomas are classified by size (either microadenomas or macroadenomas) and their ability to secrete hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types. Nonfunctioning or nonsecretory adenomas do not secrete hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types but can compress surrounding pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types tissue, leading to hypopituitarism Hypopituitarism Hypopituitarism is a condition characterized by pituitary hormone deficiency. This condition primarily results from a disease of the pituitary gland, but it may arise from hypothalamic dysfunction. Pituitary tumors are one of the most common causes. The majority of cases affect the anterior pituitary lobe (adenohypophysis), which accounts for 80% of the gland. Hypopituitarism. Secretory adenomas secrete various hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types depending on the cell type from which they evolve, leading to hyperpituitarism Hyperpituitarism Disease of the glandular, anterior portion of the pituitary resulting in hypersecretion of adenohypophyseal hormones such as growth hormone; prolactin; thyrotropin; luteinizing hormone; follicle stimulating hormone; and adrenocorticotropic hormone. Hyperpituitarism usually is caused by a functional adenoma. Hyperprolactinemia
  • Hyperprolactinemia Hyperprolactinemia Hyperprolactinemia is defined as a condition of elevated levels of prolactin (PRL) hormone in the blood. The PRL hormone is secreted by the anterior pituitary gland and is responsible for breast development and lactation. The most common cause is PRL-secreting pituitary adenomas (prolactinomas). Hyperprolactinemia: elevated levels of prolactin Prolactin A lactogenic hormone secreted by the adenohypophysis. It is a polypeptide of approximately 23 kd. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Breasts: Anatomy in the blood. The most common cause of hyperprolactinemia Hyperprolactinemia Hyperprolactinemia is defined as a condition of elevated levels of prolactin (PRL) hormone in the blood. The PRL hormone is secreted by the anterior pituitary gland and is responsible for breast development and lactation. The most common cause is PRL-secreting pituitary adenomas (prolactinomas). Hyperprolactinemia is a prolactin-secreting adenoma known as a prolactinoma Prolactinoma A pituitary adenoma which secretes prolactin, leading to hyperprolactinemia. Clinical manifestations include amenorrhea; galactorrhea; impotence; headache; visual disturbances; and cerebrospinal fluid rhinorrhea. Hyperprolactinemia. Presentations can include galactorrhea Galactorrhea Excessive or inappropriate lactation in females or males, and not necessarily related to pregnancy. Galactorrhea can occur either unilaterally or bilaterally, and be profuse or sparse. Its most common cause is hyperprolactinemia. Hyperprolactinemia (milky discharge), oligomenorrhea Oligomenorrhea Polycystic Ovarian Syndrome, erectile dysfunction Erectile Dysfunction Erectile dysfunction (ED) is defined as the inability to achieve or maintain a penile erection, resulting in difficulty to perform penetrative sexual intercourse. Local penile factors and systemic diseases, including diabetes, cardiac disease, and neurological disorders, can cause ED. Erectile Dysfunction, and in the case of large tumors, headaches and visual changes. 
  • Acromegaly Acromegaly A condition caused by prolonged exposure to excessive human growth hormone in adults. It is characterized by bony enlargement of the face; lower jaw (prognathism); hands; feet; head; and thorax. The most common etiology is a growth hormone-secreting pituitary adenoma. Acromegaly and Gigantism and gigantism Gigantism The condition of accelerated and excessive growth in children or adolescents who are exposed to excess human growth hormone before the closure of epiphyses. It is usually caused by somatotroph hyperplasia or a growth hormone-secreting pituitary adenoma. These patients are of abnormally tall stature, more than 3 standard deviations above normal mean height for age. Acromegaly and Gigantism: caused by excess production of pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types GH. Typically, gigantism Gigantism The condition of accelerated and excessive growth in children or adolescents who are exposed to excess human growth hormone before the closure of epiphyses. It is usually caused by somatotroph hyperplasia or a growth hormone-secreting pituitary adenoma. These patients are of abnormally tall stature, more than 3 standard deviations above normal mean height for age. Acromegaly and Gigantism refers to the tall stature seen in excess GH states in children before growth plate closure, and acromegaly Acromegaly A condition caused by prolonged exposure to excessive human growth hormone in adults. It is characterized by bony enlargement of the face; lower jaw (prognathism); hands; feet; head; and thorax. The most common etiology is a growth hormone-secreting pituitary adenoma. Acromegaly and Gigantism is the result of excess GH after growth plate closure leading to large extremities and characteristic facies. 
  • Secondary adrenal insufficiency Secondary adrenal insufficiency Deficiency in pituitary adrenocorticotropic hormone (ACTH) secretion. Adrenal Insufficiency and Addison’s Disease: condition in which there is insufficient production of ACTH in the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland, resulting in atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation of the adrenal glands Adrenal Glands The adrenal glands are a pair of retroperitoneal endocrine glands located above the kidneys. The outer parenchyma is called the adrenal cortex and has 3 distinct zones, each with its own secretory products. Beneath the cortex lies the adrenal medulla, which secretes catecholamines involved in the fight-or-flight response. Adrenal Glands: Anatomy and adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison’s Disease. Secondary adrenal insufficiency Secondary adrenal insufficiency Deficiency in pituitary adrenocorticotropic hormone (ACTH) secretion. Adrenal Insufficiency and Addison’s Disease presents clinically with signs of low glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids ( fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, and hypoglycemia Hypoglycemia Hypoglycemia is an emergency condition defined as a serum glucose level ≤ 70 mg/dL (≤ 3.9 mmol/L) in diabetic patients. In nondiabetic patients, there is no specific or defined limit for normal serum glucose levels, and hypoglycemia is defined mainly by its clinical features. Hypoglycemia), low mineralocorticoids Mineralocorticoids Mineralocorticoids are a drug class within the corticosteroid family and fludrocortisone is the primary medication within this class. Fludrocortisone is a fluorinated analog of cortisone. The fluorine moiety protects the drug from isoenzyme inactivation in the kidney, allowing it to exert its mineralocorticoid effect. Mineralocorticoids ( hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia, and hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia), and low androgens Androgens Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens and Antiandrogens (low libido, loss of sexual hair, and amenorrhea Amenorrhea Absence of menstruation. Congenital Malformations of the Female Reproductive System in women).
  • Central diabetes insipidus Diabetes Insipidus Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus ( DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus): condition in which the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy are unable to concentrate urine because of a lack of circulating ADH. These low levels of ADH are due to either decreased production within the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus or decreased release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology from the posterior pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland. Presentation is with polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation, nocturia Nocturia Frequent urination at night that interrupts sleep. It is often associated with outflow obstruction, diabetes mellitus, or bladder inflammation (cystitis). Diabetes Insipidus, and polydipsia Polydipsia Excessive thirst manifested by excessive fluid intake. It is characteristic of many diseases such as diabetes mellitus; diabetes insipidus; and nephrogenic diabetes insipidus. The condition may be psychogenic in origin. Diabetes Insipidus. Central and nephrogenic DI Nephrogenic DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). In nephrogenic DI, the kidneys fail to respond to circulating ADH. Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus are differentiated based on measured ADH levels and response to the water deprivation test Water Deprivation Test Diabetes Insipidus. Central DI Central DI A genetic or acquired polyuric disorder caused by a deficiency of vasopressins secreted by the neurohypophysis. Clinical signs include the excretion of large volumes of dilute urine; hypernatremia; thirst; and polydipsia. Etiologies include head trauma; surgeries and diseases involving the hypothalamus and the pituitary gland. This disorder may also be caused by mutations of genes such as arvp encoding vasopressin and its corresponding neurophysin (neurophysins). Diabetes Insipidus is treated with desmopressin Desmopressin Hemophilia.
  • Syndrome of inappropriate antidiuretic hormone Antidiuretic hormone Antidiuretic hormones released by the neurohypophysis of all vertebrates (structure varies with species) to regulate water balance and osmolarity. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a cystine. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the kidney collecting ducts to increase water reabsorption, increase blood volume and blood pressure. Hypernatremia ( SIADH SIADH Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). SIADH is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. S Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)):  disorder of impaired water excretion due to the inability to suppress the secretion Secretion Coagulation Studies of ADH. This syndrome can be due to various causes, including increased production by the pituitary Pituitary A small, unpaired gland situated in the sella turcica. It is connected to the hypothalamus by a short stalk which is called the infundibulum. Hormones: Overview and Types gland due to trauma, disease, or certain medications, the ectopic secretion Secretion Coagulation Studies of ADH by cancer, or hereditary causes (nephrogenic SIADH SIADH Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). SIADH is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. S Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)). Syndrome of inappropriate antidiuretic hormone Antidiuretic hormone Antidiuretic hormones released by the neurohypophysis of all vertebrates (structure varies with species) to regulate water balance and osmolarity. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a cystine. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the kidney collecting ducts to increase water reabsorption, increase blood volume and blood pressure. Hypernatremia should be suspected in any individual with hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia, hypoosmolality, and high urine osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation.

References

  1. Welt, C. K. (2021). Hypothalamic-pituitary axis. UpToDate. Retrieved August 13, 2021, from https://www.uptodate.com/contents/hypothalamic-pituitary-axis 
  2. Ganapathy, M.K. (2021). Anatomy, head and neck, pituitary gland. StatPearls. Retrieved August 13, 2021, from https://www.statpearls.com/articlelibrary/viewarticle/692/ 
  3. M.D., A. K. L., & M.D., T. L. (2019). Histology and Cell Biology: An Introduction to Pathology, 5th ed. Elsevier.

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