Regulation of growth hormone secretion :::
As mentioned above (under feed back mechanism ) secretion of all hormones are regulated by hypothalamus Decrease in GH in blood hypoglycaemia exercise fasting protein meal infusion of aminoacids specially arginine increase in glucagon pyrogen or deep sleep are the stimuli which cause hypothalamus to release growth hormone releasing factor (GHRF) This stimulates anterior pituitary gland to release its growth hormone Increase in GH in blood causes inhibition of the release of GH by negative feed back mechanism
Dysfunction of acidophilic cells of anterior pitutary :::
Hypersecretion of GH in the young causes Gigantism whereas in adults it causes Acromegadi Hyposecretion of GH in young causes Dwarfism and in adults Acromicra
In gigantism the patient is very tall (7-8)ft The development of muscles and viscera is proportionally greater Patient has hyperglycemia glycosuria with increased B.M.R. and sweating Gigantism starts from adolescence
In Acromegali there is overgrowth of the two jaws the molar bones the supraorbital ridges etc Hands and feet are also enlarged and there is bowing of the spine There is increase in the amount of subcutaneous tissue of the hand feet scalp nose lips and skin The tongue is also enlarged Metabolism is also increased and the patient shows hyperglycemia glycosuria increased B.M.R. and sweating Acromegali starts after puberty
Dwarfism is characterised by decrease in the height of the patient (about 3 ft or less ) The sex organs may not grow but intelligence is normal and proportionate to age The metabolism is also normal
In acromicra the bones of hands face and feet are small There is loss of hair and sexual functions This condition however is very rare
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