The pituitary pituitary or gland How does the adenohypophysis system work?

The pituitary pituitary or gland is a small endocrine gland the size of a pea located at the base of the brain, under the hypothalamus and weighs 0.5 grams in humans. It is often considered the "master gland" of the body, since it regulates most of the other endocrine glands and plays an important role in growth regulation, metabolism, reproduction and other bodily functions.

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• Pituitary pituitary gland function or gland
  • The hypothalamus and its relationship with the pituitary gland
  • Adenohypophysis
• Hypothalamus hypophysary system
  • How hormones are released
  • Hormones segregated by the previous pituitary
• Cortico -adrenal hypophytic hypothalamus axis
  • Functions of adrenocortical hormones
  • Adrenocortical hormones deficit
  • Excess corticosupranal hormones
• Hypothalamus hypophytic thyroid
  • Functions of thyroid hormones
  • Hypothyroidism
  • Hyperthyroidism
• Gonadal hypophytic hypothamphy
  • Functions of sex hormones
    • Andogens
    • The estrogens
    • The progestogens
• Prolactin axis
• Growth hormone axis
  • References

Pituitary pituitary gland function or gland

The pituitary gland is often called the master gland Because it controls other hormonal glands in your body, including thyroid and adrenal glands, ovaries and testicles.

The pituitary gland It is divided into three lobes: The anterior lobe, the intermediate lobe and the posterior lobe.

• He anterior lobe is responsible for the production and secretion of hormones As growth hormone, thyroid stimulating hormone, adrenocortopic hormone and stimulating follicle hormone and luteinizing hormone, which are responsible for growth regulation, metabolism and function of sexual glands.
• The intermediate lobe Release a hormone that stimulates melanocytes, cells that control pigmentation (skin color) through melanin production.
• He posterior lobe, On the other hand, it does not produce hormones, but Store and release two hormones produced by the hypothalamus: Antidiuretic hormone (ADH) and oxytocin. ADH regulates the amount of water reabsorbed by the kidneys, while oxytocin is responsible for uterine contraction during childbirth and milk release during breastfeeding.

The pituitary is controlled by the hypothalamus, a structure in the brain that produces hormones that stimulate or inhibit the secretion of pituitary hormones. Hypothalamic hormones are transported to the pituitary gland through a network of blood vessels called the pituitary portal system. This relationship between the hypothalamus and the pituitary is known as the hypothalamus-hypopysarian axis.

Secret hormones of both the anterior and from the back of the gland. Hormones are chemical substances that transport messages from one cell to another through their bloodstream.

The hypothalamus and its relationship with the pituitary gland

This organs serves as a communications center for the pituitary gland, by sending messages or signals to the pituitary gland in the form of hormones that travel through the bloodstream and nerves through the pituitary stem. These signals, in turn, control the production and release of other hormones of the pituitary gland that are sent to other glands and organs in the body.

The hypothalamus influences the functions of temperature regulation, food intake, thirst intake and water, sleep and vigil patterns, emotional behavior and memory.

Adenohypophysis

Adenohypophysis, also known as anterior lobe of the pituitary, It is one of the two parts of the pituitary gland, a small endocrine gland located at the base of the brain. Adenohypophysis is responsible for the production and secretion of several hormones that are essential for growth regulation, reproduction, metabolism and other body functions.

Adenohypophysis is composed of different types of cells, each of which produces a specific hormone. These types of cells include:

1. Somatotropas cells: They produce growth hormone (GH), which stimulates cell growth and reproduction in humans and other animals.
2. Lactropas cells: They produce the hormone prolactin (PRL), which stimulates milk production in women after childbirth.
3. Corticotropic cells: They produce the adrenocortopic hormone (ACTH), which stimulates the production of steroid hormones in the adrenal glands.
4. Thyrootropic cells: They produce thyroid stimulating hormone (TSH), which stimulates the production and secretion of thyroid hormones by the thyroid gland.
5. Gonadotropas cells: They produce the stimulating follicle hormone (FSH) and the luteinizing hormone (LH), which are essential for reproductive function in men and women.

The production and release of these hormones is regulated by the hypothalamus, a brain structure that produces liberating and inhibitory hormones that control the secretion of adenohypophysis hormones. These hypothalamic hormones are transported to adenohypophysis through a system of blood vessels called a pituitary portal system.

Adenohypophysis disorders can have a significant impact on the health and well -being of a person. Hyperfunction of adenohypophysis can result in an excess of hormones produced, which can cause a variety of symptoms, such as changes in weight, physical appearance, sexual function and mood. On the other hand, the hypipophysis pituitary.

Hypothalamus hypophysary system

The hypothalamus-hydrophysarian carrier system is a specialized blood vessel system that Connect the hypothalamus with the pituitary. This system is essential for the regulation of pituitary hormones, which are produced and secreted by the pituitary.

The hypothalamus-hypopysarian portal system consists of two pairs of blood vessels: the previous pituitary carrier system and the posterior pituitary system. The anterior hypophyseal holder system connects the hypothalamus with the adenohypophysis or anterior lobe of the pituitary.

In the anterior hypophyseal portal system, neuroendocrine cells of the hypothalamus synthesize and release specific liberating hormones and inhibitors that are transported by blood vessels to adenohypophysis. These hormones act on specific cells in adenohypophysis, stimulating or inhibiting the release of specific pituitary hormones. Two other specific hormones, antidiuretic hormone (ADH) and oxytocin also release, which are transported by blood vessels to neurohypophysis. These hormones are stored and then released by neurohypophysis in response to specific hypothalamus signs.

Adenohypophysis It works as a true endocrine gland, since it is formed by neurosecretory cells. But, in addition, it is also under strict hormonal control by the hypothalamus.

Hypothalamus hormones are generally small peptides and are called liberating factors or Liberating hormones, AND INHIBIT FACTORS U inhibitory hormones, depending whether they act by stimulating or inhibiting the hormonal secretion of the previous pituitary.

How hormones are released

There are hypothalamic nuclei, from the periventricular zone (for example, the arched, the periventricular, the medial preoptic area) that synthesize and send the release or inhibition factors in the portal circulation (the capillaries of the average eminence). From there they are transported to adenohypophysis, where they stimulate or inhibit cells that secrete pituitary hormones.

Adenohypophyseal hormones act on other glands of the body, and stimulate the release of blood hormones. Some of these glands are the adrenal glands, the thyroid, the gonads, the mammary glands.

Hormones segregated by the previous pituitary

Of the hormones segregated by adenohypophysis, four are tropic hormones, that is, they have as target another gland on which they act to regulate their hormonal production. These are the following:

• Adrenocortopic or corticotropin (Acth) hormone (ACTH). The acronym with which hormones are usually known corresponds to their English denomination (Acth, adrenocorticotropic hormone).
• Thyroid stimulating hormone (TSH) or thyrotropin

They include the folk -stimulating hormone (FSH) and luteinizing hormone (LH)

Apart from these tropic hormones, also secret adenohypophysis:

• Prolactin
• Growth hormone (GH) or somatotropin

Taking into account the target organ of pituitary hormones, we can distinguish different hormonal axes:

• Corticoadrenal hypotalamohypophytic axis
• Thyroid hypothalamohypophytic axis
• Gonadal hypotalamohypophytic axis
• Prolactin axis
• Growth hormone axis

The accurate regulation of the hypothalamus-hydrophyseal system is essential for the appropriate hormonal balance in the human body. Dysfunction of the hypothalamus-hypofysarian port.

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Cortico -adrenal hypophytic hypothalamus axis

The hypothalamus-hypophyseal-adrenal axis (HHA), also known as hypothala-hypophyseal-critical-rendic axis, is a Complex communication system between hypothalamus, pituitary glands and adrenal glands (also known as adrenal glands). This axis is essential for the body's response to stress and for the regulation of cortisol levels, a steroid hormone produced by the adrenal glands.

The HHA axis begins in the hypothalamus, where neurons produce and secrete a corticotropin liberating hormone (CRH). CRH travels through the pituitary portal system and reaches adenohypophysis, where it stimulates the production and secretion of adrenocortopic hormone (ACTH) in corticotropic cells. Acth is released in blood circulation and travels through the body until reaching the adrenal glands.

In the adrenal glands, the ACTH stimulates the production and release of cortisol, a steroid hormone that helps regulate metabolism, inflammatory response and stress response. Once cortisol levels in the body reach a certain threshold, hypothalamus and pituitary.

The HHA axis is also modulated by a series of negative and positive feedback mechanisms. High levels of cortisol in the body inhibit the production and release of CRH and ACTH, while low cortisol levels stimulate the production and release of these hormones.

The basic scheme is as follows:

Functions of adrenocortical hormones

Glucocorticoids:

• Increase blood glucose level, they accelerate protein degradation.
• In high concentrations, they have anti -inflammatory effects.

Mineralocorticoids:

• Cause retention of sodium ions and elimination of potassium ions by urine.

Adrenocortical hormones deficit

A hormonal deficit produces Addison's disease, which consists of a pituitary of the adrenal glands. It has the following consequences: tiredness, apathy, cognitive deficits, depression, etc.

Excess corticosupranal hormones

In chronic stress situations, a large amount of glucocorticoids are released and that makes a depression in the immune system, an increase in blood pressure, damage to nerve tissue (for example, in the hippocampus) in the immune term (for example, in the hippocampus) and muscle, growth inhibition, infertility, etc.

Hypothalamus hypophytic thyroid

The hypothalamus-hypopysarian-pyroid axis (HHT) is a complex communication system between the hypothalamus, the pituitary gland and the thyroid gland. This axis is essential for the regulation of metabolism and growth, as well as for the proper function of organs and tissues throughout the body.

The HHT axis begins in the hypothalamus, where neurons produce and secrete a thyrotropin liberating hormone (TRH). The THR travels through the pituitary portal system and reaches adenohypophysis, where it stimulates the production and secretion of thyroid stimulating hormone (TSH) in thyrotropic cells. The TSH is released in the blood circulation and travels through the body until it reaches the thyroid gland.

In the thyroid gland, TSH stimulates the production and release of thyroid hormones, such as thyroxine (T4) and triiodothyronin (T3). These hormones are essential for normal growth and development, as well as for metabolism and function of organs and tissues throughout the body. Once the levels of thyroid hormones in the body reach a certain threshold, the hypothalamus and the pituitary gather.

The HHT axis is also modulated by a series of negative and positive feedback mechanisms. High levels of thyroid hormones in the body inhibit the production and release of TRH and TSH, while low levels of thyroid hormones stimulate the production and release of these hormones.

The basic scheme is as follows:

Functions of thyroid hormones

The main role is to regulate the metabolic processes and especially of the use of carbohydrates.

It also influences growth and development, both bodily and the nervous system.

Hypothyroidism

Thyroxine is the only substance produced by the body that contains iodine; so that, The manufacture of this hormone depends critically on the supply of iodine. In areas where the food content in food is poor, many people develop hyperthyroidism. In these cases, the thyroid is enlarged in an attempt to produce more hormone, a situation known as goiter. Iodized salts are currently used to prevent this alteration.

If it is during development, there is an arrest of body growth, facial malformations and reduction in the size and cell structure of the brain. This entails a congenital deficiency that is called cretinism.

If it occurs later, behavioral disorders such as apathy, depression, delayed speech, etc.

Hyperthyroidism

Generally, physiological and behavioral alterations: insomnia, irritability, nervousness, increase in heart rate and blood pressure, temperature alterations, weight decrease, etc.

Gonadal hypophytic hypothamphy

This axis is very important for sexual development and reproduction. This axis regulates the production and release of sex hormones, including estrogens, progesterone and testosterone, which are essential for the development and maintenance of secondary sexual characteristics, as well as for the regulation of the menstrual cycle and fertility.

The HHG axis begins in the hypothalamus, where neurons produce and secrete specific liberating hormones, such as the gonadotropin -release hormone (GNRH). The GNRH travels through the pituitary portal system and reaches the adenohypophysis, where it stimulates the production and release of gonadotropic hormones, including the luteinizing hormone (LH) and the stimulating follicle hormone (FSH).

In women, LH and FSH stimulate ovaries to produce estrogens and progesterone, which are essential for the regulation of the menstrual cycle and fertility. In man, LH stimulates Leydig cells in the testicles to produce testosterone, which is essential for male sexual function and sperm production.

The HHG axis is also modulated by a series of negative and positive feedback mechanisms. High levels of sex hormones in the body inhibit the production and release of GNRH, LH and FSH, while the low levels of sex hormones stimulate the production and release of these hormones.

The basic scheme is as follows:

The control mechanisms are similar to those explained by the previous two axes.

Functions of sex hormones

Andogens

• Promote the development, growth and maintenance of male reproductive organs.
• Promote the development of male secondary sexual characteristics (body shape, tone, beard, etc.).
• They stimulate protein metabolism.

The estrogens

• Promote the development, growth and maintenance of female reproductive organs.
• They promote the development of female secondary sexual characteristics (body shape, breasts, hair pattern, etc.).

The progestogens

• Prepare the walls of the uterus for the implantation of the fertilized ovule.
• Prepare the breasts to secrete milk.

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Prolactin axis

The prolactin axis is a communication system between the hypothalamus, the pituitary and the mammary glands, which is essential for the regulation of hormone production prolactin. Prolactin is a peptide hormone produced by the previous pituitary cell cells, and its main function is to stimulate the production and release of milk in the mammary glands after childbirth.

The prolactin axis begins in the hypothalamus, where neurons produce and secrete the prolactin -liberating hormone (PRL), also known as thyrotropin liberating hormone (TRH), which stimulates the production and secretion of prolactin in adenohypophysis. Unlike other endocrine axes, the prolactin axis is not subject to negative feedback control, which means that prolactin secretion can continue even in the presence of high levels of the hormone in the body.

Prolactin stimulates milk production by mammary glands. During breastfeeding, the hypothalamus reduces dopamine secretion so that a sufficient level of prolactin occurs and milk production does not stop.

Prolactin production is influenced by a series of factors, including pregnancy, breastfeeding, stress and nipples stimulation. During pregnancy, prolactin levels increase significantly to stimulate milk production and release. Stimulation of nipples during breastfeeding can also increase prolactin production, which can help maintain milk production.

Growth hormone axis

It is a communication system between the hypothalamus, the pituitary and the liver, which is essential for the Growth regulation and body development. GH is a protein hormone produced and secreted by the somatotropas cells of the previous pituitary gland, and its main function is to stimulate cell growth and division throughout the body.

The GH axis begins in the hypothalamus, where neurons produce and secrete the growth hormone of the growth hormone (GHRH), which stimulates the production and secretion of GH in the adenohypophysis. In turn, GH stimulates the production of hormone similar to type 1 insulin (IGF-1) in the liver and other tissues. IGF-1 is an important growth factor that stimulates cell growth and division throughout the body.

Growth or somatotropin hormone stimulates body growth through the production of substances that regulate bone growth. It is controlled by the GHRH that stimulates its production and somatostatina, which inhibits it.

GH production is influenced by a series of factors, including sleep, exercise and nutrition. During sleep, GH levels increase significantly, which can help stimulate tissue growth and repair. Exercise can also increase GH production, which can help stimulate muscle and bone growth. Proper nutrition, especially the proper protein consumption, is essential for the production of GH and IGF-1.

GH axis disorders can have a significant impact on body growth and development. GH axis hyperfunction can result in excessive GH production, which can cause a variety of symptoms, such as Gigantism in children, However, if the excess is in adulthood no longer produces gigantism because the bones cannot grow in length, but it occurs acromegaly, characterized by an increase in some tissues such as jaw and hand and feet joints.

On the other hand, GH axis pituitary can lead to GH deficiency, which can cause Growth delay, dwarfism and other health problems.

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