DrShashikant RSitre Department of Zoology NSScience and Arts College Bhadrawati Hormones of Adenohypophysis The Adenohypophyis of the pituitary gland is characteristically glandular in nature and ID: 1046375
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1. HORMONES OF ADENOHYPOPHYSISDr.Shashikant R.SitreDepartment of ZoologyN.S.Science and Arts College, Bhadrawati
2. Hormones of AdenohypophysisThe Adenohypophyis of the pituitary gland is characteristically glandular in nature and secretes six different hormones which, are the trophic hormones.A trophic hormone stimulates some other endocrine gland as its target organ to secret its own hormones.
3. Trophic HormonesThe trophic hormones are - Gonadotropins – FSH (Follicle stimulating HormoneLH (luteinizing Hormone) in female ICSH (Interstitial Cell Stimulating Hormone) in MalesLuteotropic hormone or Lactogenic HormoneACTH (Adrenocorticotrophic Hormone) adrenaal cortex stimulatorTSH (Thyroid Stimulating Hormone)Adipose kinetic hormones
4. The production of these hormones is due to secretion of certain chemical messengers or regulation factors or releasing factors by the neurosecretory cells of the hypothalamus which after passing down into the sinusoids of adenohypophysis through the hypophyseal portal system, stimulates the various hormone producing cells of the pituitary gland to discharge their products. The chemical messengers or releasing factors in turn are secreted in response to various chemical and nervous stimuli.
5. Somatotropin (Growth Hormone)The growth hormone is a protein, secreted by Acidophilic cells of the adenohypophisis.The growth hormone of humans has amolecular weight of 21500 and consist of 190 amino acids.Its basic function is to stimulate both body weight and rate of growth of body for muscle tissue, bon structure, cartilage etc.
6. Somatotropin….It also influences the protein, carbohydrate and fat metabolism to a great extent.
7. Somatotropin….Hyposecretion – DwarfismOf the growth hormone during the years of skeletal growth of an individual results in a stunted skeletal development and retarded growth is called Dwarfism.
8. Somatotropin…Hypersecretion –Hypersecretion of growth hormone prior to puberty results in Gigantism, a condition showed by a general overgrowth of the skeleton resulting in individuals of 7 or 8 feet or more in height. The limbs are disproportinally long.Hypersecretion of the hormone after usual age of skeletal growth results in Acromegaly. In this disease overgrowth of bones of the hands, feet and in particular jaws and cheeks takes place. Excessive growth of fibrous tissue resulting in thickened nose, lips, eyelids and broadened fingertips.
9. 2. TSH (Thyroid Stimlulating Hormone)This hormone is produced by Basophilic cells of adenohypophysis.It is a glycoprotein of about 10,000 molecular weight. It controls the various aspects of the thyroid gland function including the development and maintainance. Thyrotropin also stimulates iodine accumulation, the conversion of iodine into the thyroid hormones, and their release from the gland into the circulation.If there is an excess of secretion there is increase in the size of thyroid gland.
10. 3. ACTH (Adrenocorticotropic Hormone)This hormone is secreted by basophilic cells of the adenohypophysis and stimulates the adrenal cortex, causing the adrenal cortex to grow and to secrete all of its normal hormones at an increased rate. The adrenal cortex is the main target organ upon which ACTH acts. The steroid hormonal secretions of adrenal cortex act throughout the body to –Increae the rate of gluconeogenesisTo increase the rat of protein catabolismTo increase the rate of fat catabolismo
11. Therefore ACTH has profound effects on carbohydrate, protein and fat metabolism.
12. Deficiency & Oversecretion of ACTH…Deficiency of ACTH causes acute Psoriasis, and Dermatitis. Its over secretion causes Cushing Disease which is characterized by obesity of trunk , face and buttocks but not the limbs, Cynosis of face,hands and feet, Pigmentation of skin and excessive growth of hair, demineralization of bones, loss of sexual functions and hyperglycemia.
13. 4. GTH (Gonadotropic Hormones) =3The FSH, LH in female and ICSH in male and Prolactin are referred as to Gonadotropin Hormones.Three Gonadotropic hormones are secreted by adenohypophysis are proteins.FSH and LH are Glycoproteins while LTH is Polypeptide. The gonatdotrophic hormones stimulate various activities of the gonads.
14. a) FSH Follicle Stimulating Hormone – The FSH stimulates the growth of the ovarian follicles upto the point ovulation in the female and in male with the development of seminiferous tubules and maintainance of spermatogenesis.
15. b) ICSH or LH In the female the LH (Luteinizing hormone) works with the FSH and is responsible for the final maturation of the ovarian follicles and ovulation. These two gonadotropins are also responsible for stimulatin of ovaries to produce estrogen and androgen in males.
16. ICSH…In males Interstitial Cell stimulating hormones stimulates the Leydig cells of the testes for the secretion of male hormone testosterone.
17. c. Prolactin or LTH It is connected with reproduction of mammals. In mammals this hormone induces milk secretin in mammary glands shortly after birth. It maintains corpus luteum which is necessary for maintainance of pregnany.