All Topics  
Pituitary gland

 

 
   Email Print
   Bookmark   Link
 

 

Pituitary gland
 
 
  Topics Pituitary gland Topic Home

The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g (0.02 oz.). It is a protrusion off the bottom of the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
 at the base of the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
, and rests in a small, bony cavity (sella turcica
Sella turcica

The sella turcica literally...
) covered by a dural
Dura mater

The dura mater , or pachymeninx, is the tough and inflexible outermost of the three layers of the meninges surrounding the brain and spinal cord....
 fold (diaphragma sellae
Diaphragma sellae

The diapragma sellae or sellar diaphragm is the circular fold of dura mater that almost completely roofs the fossa hypophyseos in the sphenoid bone of the skull....
). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid
Sphenoid

Sphenoid may refer to:* In anatomy, the sphenoid bone* In geometry, a tetrahedron with mirror symmetry...
 bone in the middle cranial fossa
Middle cranial fossa

The middle fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior cranial fossa by the Clivus and the petrous crest....
 at the base of the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
.

The pituitary gland secretes hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s regulating homeostasis
Homeostasis

Homeostasis is the property of a system, either open system or closed system, that regulates its internal environment and tends to maintain a stable, constant condition....
, including tropic hormones that stimulate other endocrine glands
Endocrine glands

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct....
.






Discussion
Ask a question about 'Pituitary gland'
Start a new discussion about 'Pituitary gland'
Answer questions from other users
Full Discussion Forum



Encyclopedia


The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g (0.02 oz.). It is a protrusion off the bottom of the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
 at the base of the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
, and rests in a small, bony cavity (sella turcica
Sella turcica

The sella turcica literally...
) covered by a dural
Dura mater

The dura mater , or pachymeninx, is the tough and inflexible outermost of the three layers of the meninges surrounding the brain and spinal cord....
 fold (diaphragma sellae
Diaphragma sellae

The diapragma sellae or sellar diaphragm is the circular fold of dura mater that almost completely roofs the fossa hypophyseos in the sphenoid bone of the skull....
). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid
Sphenoid

Sphenoid may refer to:* In anatomy, the sphenoid bone* In geometry, a tetrahedron with mirror symmetry...
 bone in the middle cranial fossa
Middle cranial fossa

The middle fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior cranial fossa by the Clivus and the petrous crest....
 at the base of the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
.

The pituitary gland secretes hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s regulating homeostasis
Homeostasis

Homeostasis is the property of a system, either open system or closed system, that regulates its internal environment and tends to maintain a stable, constant condition....
, including tropic hormones that stimulate other endocrine glands
Endocrine glands

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct....
. It is functionally connected to the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
 by the median eminence
Median eminence

The median eminence is part of the inferior boundary for the hypothalamus part of the human brain. A small swelling on the tuber cinereum posterior to the infundibulum - atop the pituitary stalk - the median eminence lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region...
.

Sections

Located at the base of the brain, the pituitary is linked in function to the hypothalamus. It is composed of two lobes: the adenohypophysis and neurohypophysis. The adenohypophysis, also referred to as the anterior pituitary is divided into anatomical regions known as the pars tuberalis, pars intermedia, and pars distalis. The neurohypophysis, also referred to as the posterior pituitary. The pituitary is functionally linked to the hypothalamus by the pituitary stalk
Pituitary stalk

The pituitary stalk is the connection between the hypothalamus and the posterior pituitary.It carries axons from the magnocellular neurosecretory cells of the hypothalamus down to the posterior pituitary where they release their hormones into the blood....
, whereby hypothalamic releasing factors are released and, in turn, stimulate the release of pituitary hormones. The pituitary gland is known as the master endocrine gland. But the hypothalamus truly is the master endocrine gland, because it controls both lobes of the pituitary gland.

Anterior pituitary (Adenohypophysis)

The anterior pituitary
Anterior pituitary

The anterior pituitary comprises the Anterior#Usage in human anatomy lobe of the pituitary gland and is part of the endocrine system. Unlike the posterior pituitary, the anterior lobe is genuinely glandular, hence the root adeno in its name....
 synthesizes and secretes important endocrine hormones, such as ACTH
Adrenocorticotropic hormone

Adrenocorticotropic hormone is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress ....
, TSH
Thyroid-stimulating hormone

Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland....
, PRL
Prolactin

Prolactin or Luteotropic hormone is a peptide hormone primarily associated with lactation. In breastfeeding, the act of an infant suckling the nipple stimulates the production of prolactin, which fills the breast with milk via a process called lactogenesis, in preparation for the next feed....
, GH
Growth hormone

Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland....
, endorphin
Endorphin

Endorphins are endogenous opioid polypeptide compounds. They are produced by the pituitary gland and the hypothalamus in vertebrates during strenuous exercise, excitement, pain, and orgasm, and they resemble the opiates in their abilities to produce analgesia and a sense of well-being....
s, FSH
Follicle-stimulating hormone

Follicle-stimulating hormone is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body....
, and LH. These hormones are released from the anterior pituitary under the influence of hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
. Hypothalamic hormones are secreted to the anterior lobe by way of a special capillary
Capillary

Capillaries are the smallest of a body's blood vessels, measuring 5-10 micrometre in diameter, which connect arterioles and venules, and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissue s....
 system, called the hypothalamic-hypophyseal portal system. The anterior pituitary develops from a depression in the dorsal wall of the pharynx (stomodial part) known as Rathke's pouch
Rathke's pouch

In embryogenesis, Rathke's pouch is a depression in the roof of the developing mouth in front of the buccopharyngeal membrane. It gives rise to the anterior pituitary, a part of the endocrine system....
.

Posterior pituitary (Neurohypophysis)


The hormones secreted by the posterior pituitary are
  • Oxytocin
    Oxytocin

    Oxytocin is a mammalian hormone that also acts as a neurotransmitter in the brain.It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating childbirth and breastfeeding, respectively....
    , most of which is released from the paraventricular nucleus
    Paraventricular nucleus

    The paraventricular nucleus is a neuronal nucleus in the hypothalamus. It contains multiple subpopulations of neurons that are activated by a variety of stressful and/or physiological changes....
     in the hypothalamus
    Hypothalamus

    The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
  • Antidiuretic hormone (ADH, also known as vasopressin
    Vasopressin

    Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a hormone found in most mammals, including humans....
     and AVP, arginine vasopressin), the majority of which is released from the supraoptic nucleus
    Supraoptic nucleus

    The supraoptic nucleus is a nucleus of magnocellular neurosecretory cells in the hypothalamus of the mammalian brain. The nucleus is situated at the base of the brain, adjacent to the optic chiasm, and, in humans, it contains about 3,000 neurons....
     in the hypothalamus
    Hypothalamus

    The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....


Oxytocin is one of the few hormones to create a positive feedback loop. For example, uterine contractions stimulate the release of oxytocin from the posterior pituitary, which, in turn, increases uterine contractions. This positive feedback loop continues throughout labor.

Intermediate lobe

There is also an intermediate lobe
Pars intermedia

Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells - Anterior pituitary basophils, chromophobes, and colloid-filled cysts....
 in many animals. For instance, in fish, it is believed to control physiological color change. In adult humans, it is just a thin layer of cells between the anterior and posterior pituitary. The intermediate lobe produces melanocyte-stimulating hormone
Melanocyte-stimulating hormone

The melanocyte-stimulating hormones are a class of peptide hormones that in nature are produced by cells in the intermediate lobe of the pituitary gland....
 (MSH), although this function is often (imprecisely) attributed to the anterior pituitary.

Functions

The pituitary hormones help control some of the following body processes:
  • Growth
    Human development (biology)

    Human development is the process of growing to maturity. In biological terms, this entails growth from a one-celled zygote to an adult human being....
  • Blood pressure
    Blood pressure

    Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
  • Some aspects of pregnancy
    Pregnancy

    Pregnancy is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of a female. In a pregnancy, there can be multiple gestations, as in the case of twins or Multiple birth....
     and childbirth
    Childbirth

    Childbirth is the culmination of a human pregnancy or gestation period with the delivery of one or more newborn infants from a woman's uterus. The process of normal human childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and delivery of the infant, and delivery of the placenta.....
     including stimulation of uterine contractions during childbirth
  • Breast milk
    Breast milk

    Breast milk refers to the milk produced by a mother to feed her baby. It provides the primary source of nutrition for newborns before they are able to eat and digest other foods; older infants and toddlers may continue to be breastfeeding....
     production
  • Sex organ
    Sex organ

    A sex organ, or primary sexual characteristic, as narrowly defined, is any of the anatomical parts of the body which are involved in sexual reproduction and constitute the reproductive system in a complex organism; in mammals, these include:...
     functions in both women and men
  • Thyroid gland function
  • The conversion of food into energy
    Energy

    In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
     (metabolism
    Metabolism

    Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
    )
  • Water
    Water

    Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
     and osmolarity regulation in the body


Pathology

Disorders involving the pituitary gland include:

Condition Direction Hormone >- | Acromegaly
Acromegaly

Acromegaly is a syndrome that results when the pituitary gland produces excess human growth hormone after epiphyseal plate closure. A number of disorders may affect the pituitary to create this circumstance, although most commonly it involves a GH producing tumor derived from a distinct type of cells and called pituitary adenoma....
 		 overproduction growth hormone
Growth hormone

Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland....
 |- | Growth hormone deficiency
Growth hormone deficiency

Growth Hormone Deficiency is a medical condition in which the body does not produce enough growth hormone . Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction....
 		 underproduction growth hormone
Growth hormone

Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland....
 |- | Syndrome of inappropriate antidiuretic hormone
Syndrome of inappropriate antidiuretic hormone

The syndrome of inappropriate antidiuretic hormone is a condition commonly found in the hospital population, especially in patients being hospitalized for central nervous system injury....
 		 overproduction vasopressin
Vasopressin

Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a hormone found in most mammals, including humans....
 |- | Diabetes insipidus
Diabetes insipidus

Diabetes insipidus is a disease characterized by polydipsia and excretion of large amounts of severely diluted polyuria, with reduction of fluid intake having no effect on the latter....
 		 underproduction vasopressin
Vasopressin

Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a hormone found in most mammals, including humans....
 |- | Sheehan syndrome 		underproduction any pituitary hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
 |- | Pituitary adenoma
Pituitary adenoma

Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 10% of intracranial neoplasia. They often remain undiagnosed, and small pituitary tumors have an estimated prevalence of 16.7% ....
 		 overproduction - | Hypopituitarism
Hypopituitarism

Hypopituitarism is the decreased secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain....
 		 underproduction any pituitary hormone


Additional images


See also

  • Head and neck anatomy
    Head and neck anatomy

    Head and neck anatomy focuses on the structures of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat....


External links