Pituitary gland

Pituitary gland

Pituitary gland

Pituitary gland is considered as the master gland as it controls the functions and secretion of most of the endocrine glands. The gland is located beneath the brain and in connection with the hypothalamus, The gland consists of 2 parts:

• Adenohypophysis: It consists of the anterior and middle lobe - developed embryonically from the roof of the mouth.
• Neurohypophysis: It consists of the posterior lobe and a part of the brain called the infundibulum ( a stalk connecting the gland to the brain) - developed from the back of the forebrain.

****Note: Hypophysis means Pituitary,..Plural: hypophyses

Hormones of the Adenohypophysis ( anterior lobe of the pituitary gland):

1. Growth hormone (G.H.)

It controls metabolism especially protein synthesis, accordingly it controls the physical growth of the body.

Hypo-secretion ( Hypo=less or weak) of this hormone during childhood causes Dwarfism and its hyper-secretion ( hyper=over) during the same period causes Gigantism.

Hyper-secretion of G.H. in adults causes Acromegaly which is characterized by increased bone growth at the extremities and characterized by enlarged hands, feet, fingers and bones of the face.

      2. Pituitary Trophins:

A group of hormones that affect the activity and secretion of other glands and includes:

1. Thyrotrophin (thyroid stimulating hormones) (TSH) ---> check out this brief topic about thyroid gland at - http://allaboutbiologyworld.blogspot.com/2016/05/thyroid-gland-brief-notes.html
2. Adrenocorticotrophic hormone (ACTH) which affects the function of the adrenal (Suprarenal) cortex.
3. Gonadotrophic hormones - Affect the function of gonads ( ovaries in females and testes in males).

This group includes:

1. Follicle stimulating hormone (FSH) which affects the growth of the ovarian follicles and formation of Graafian follicles in females and formation of seminiferous tubules, spermatozoa in male.
2. Lutinizing hormone (LH) which stimulates the formation of corpus luteum in females and the formation and secretion of interstitial cells in the testes of males.

These two hormones are important for sexual maturity as they are responsible for secretion of male and female sex hormones

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         3. Prolactin: stimulates milk formation and secretion from mammary glands ( breasts).

Hormones of the neurohypophysis ''Posterior lobe of the pituitary gland'':

Two hormones are secreted from the nerve cells in the hypothalamus and called the secretary neurons, and reach the neurohypophysis ( posterior lobe of pituitary) through the infundibulum after which they are released to the blood stream.

The two hormones are:

1. Antiduretic hormone (ADH) (Vasopression):

This hormone increases the re-absorption of water from the kidney tubules and decreasing the volume of urine excreted. In addition it increases blood pressure.

        2. Oxytocin:

This hormone affects the uterine contraction and increases it during delivery ( labour). Gynecologists use this hormone to accelerate the birth of a baby by stimulating strong contractions of uterine muscles ( synthetic type '' Pitocin'' of Oxytocin) 

In addition oxytocin stimulates the release of milk from mammary glands with the beginning of lactation ( milk letting hormone).

References used:

https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/018261s031lbl.pdf

https://www.khanacademy.org/science/health-and-medicine/advanced-endocrine-system/endocrine-system-introduction/v/hypothalamus-and-pituitary-gland

http://www.audioenglish.org/dictionary/hypophysis.htm

+My highschool Biology book which provided a lot of content.

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