Importance of the Pituitary Gland – The Master Gland
What is Pituitary Gland? Where is it Present? What are its functions?
The Pituitary gland is called as the master gland as it regulates the functions of all other endocrine glands by secreting hormones.
Lobes of Pituitary Gland and their Location:
Pituitary gland has 2 lobes. The lobe which is present towards the front of the head is called as the anterior lobe and which is located at the back is called as the posterior lobe. These lobes are located at the base of the brain about midway between the ears at the eye level. These two lobes are connected by a tiny bridge of tissue. Each lobe has distinct activities.
The Posterior Lobe and the Hypothalamus:
The posterior lobe does not secrete any hormones but acts as a store house for the hormones secreted by the hypothalamus. Hypothalamus is located in the cerebellum of the brain and acts as an endocrine gland. It controls the autonomic nervous system. It also acts as a connecting link between the cerebral cortex of the brain and the pituitary gland. The posterior lobe of the pituitary gland releases 2 hormones secreted by the hypothalamus namely oxytocin and vasopressin into the blood stream.
1. Vasopressin :
Vasopressin plays an important role in regulating the fluid balance in the body.
2. Oxytocin :
Oxytocin is thought to pace the onset and progress of labor during child birth.
The Anterior Lobe of the Pituitary:
The Anterior Lobe secretes 6 hormones which stimulate the production of hormones by other glands.
1. Somatotrophic Hormone or Growth Stimulating Hormone (GSH) :
It is also called as the growth hormone. It controls the growth rate and multiplication of all cells and tissues in the body like muscle, bone and all specialised organs.
Defects in secretion of Somatotrophic Hormone or Growth Stimulating Hormone leads to:
Gigantism: If growth hormone is secreted in excess amounts by the pituitary in the childhood, it leads to over stimulation of the growth processes causing a disorder known as gigantism. The people with this disorder grow to a height of nine feet and also weigh about 500 pounds.
Dwarfism: When the growth hormone is secreted in small amounts, dwarfism occurs. The people with this disorder are small in size but well proportioned. Neither gigantism nor dwarfism affects the basic intelligence of the patient.
Acromegaly: When the secretion is more after the full size is reached, may be because of tumour affecting the pituitary, acromegaly occurs. In this condition the bones enlarge abnormally especially of the bones of hands, feet and face.
2. Adrenocorticotrophic Hormone (ACH) :
Adrenocorticotrophic hormone stimulates the production of hormones by the adrenal cortex of the adrenal gland.
3. Thyroid Stimulating Hormone (TSH) :
Thyroid stimulating hormone is also called as thyrotrophin. Thyrotrophin stimulates the production of hormone named as thyroxine by the thyroid gland.
4. Follicle Stimulating Hormone (FSH) :
Follicle stimulating hormone stimulates the production of estrogen and testosterone. Estrogen is the female sex hormone produced by the ovaries in women whereas testosterone is the male sex hormone which produces sperms by the testicles. Follicle here refers to the Graffian follicles in the ovary which contain the developing female egg. This eggs growth is stimulated by the FSH. In males, semimal vescicles are present on either side of the prostate gland to store mature sperms.
5. Luteinizing Hormone (LH) :
Luteinizing hormone transforms the graffian follicle, after it has released the mature egg cell, into a specialised tissue called as corpus luteum. This corpus luteum produces the hormone named as progesterone to prepare the mucous lining of the uterus called as endometrium to receive the fertilized egg.
6. Luteotrophic Hormone (LTH) :
It is also called as lactogenic hormone and stimulates the mother’s mammary glands to produce milk. It also helps in the production of progesterone by the sex glands along with the LH. The Follicle Stimulating hormone, Luteinizing hormone and Lactogenic hormone are called as Gonadotrophic hormones as they all stimulate the activity of the gonads.
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