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Renin Angiotensin Mechanism.

Pituitary Gland.

 

Introduction.

  • Most important gland in the human body, also called “Master Gland”.

  • Pituitary gland along with Hypothalamus forms a “Hypothalamus-Pituitary Complex” which is considered the “Command Center” for the entire endocrine system.

  • Location:

    • It is located below the hypothalamus in the “hypophyseal fossa” of the sphenoid bone.

    • It is connected to the hypothalamus with a string called “Infundibulum”.

  • Structure:

    • Pituitary gland is a bean shaped gland.

    • 1 to 1.5 cm in length.

    • 500 mg in weight.

    • It is divided into two lobes,

      • Anterior Lobe (Adenohypophysis)

      • Posterior Lobe (Neurohypophysis)

  • Anterior Lobe of pituitary gland:

    • Also called “Adenohypophysis”.

    • Secretion of hormones is controlled by hypothalamic hormones.

    • It secretes six hormones as follows,

  • 1) Growth Hormone / Somatotropin (GH). (promotes growth).

  • 2) Thyroid Stimulating Hormone / Thyrotropin (TSH). (Stimulates the thyroid gland).

  • 3) Adrenocorticotropic Hormone (ACTH). (Stimulates Adrenal Gland).

  • 4) Follicle Stimulating Hormone (FSH). (Stimulates ovaries and testes)

  • 5) Luteinizing Hormone (LH): (Stimulates sex hormone production in gonads).

  • 6) Prolactin: (Stimulates milk production in breasts).

  • Posterior Lobe of pituitary gland:

    • Also called “Neurohypophysis”.

    • It is made up of neural tissues.

    • The hormones from this lobe are actually produced in the hypothalamus, it just acts as a storage reservoir.

    • It secretes two hormones as follows;

  • 1) Oxytocin (OT): (Contractions of uterus and ejection of milk).

  • 2) AntiDiuretic Hormone  / Vasopressin (ADH): (Increase water reabsorption)

Disorders of Pituitary Gland:

  • 1) Pituitary Dwarfism:

    • Characterized by low levels of GH causing impaired growth of the childrens.

  • 2) Gigantism: 

    • Characterized by high levels of GH causing overgrowth of the childrens.

  • 3) Acromegaly:

    • Characterized by high levels of GH causing overgrowth of the feet / face/ limb bones of adults whose growth is stopped.

  • 4) Diabetes insipidus:

    • Characterized by abnormally low levels of ADH causing increased urine formation leading to water loss and hence dehydration

Commonly Asked Questions.

  1. Which gland is called the “Master Gland”? Name its different hormones.

  2. Write a short note on Pituitary Gland.
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