<prompt> GnRH is a ?PeptideAmineSteroidNone  <response>: Ans. is a i.e., PeptideThree general classes of hormone exist : ?1 Proteins and polvpeptide The peptideprotein hormones are:i Hypothalamus :- Thyrotropin releasing hormone TRH, coicotropin-releasing hormone CRH, Growth-hormone releasing hormone GHRh, Growth hormone inhibitory hormone GHIn, i.e., somatostatin, Gonadotropin-releasing hormone GnRH.ii Anterior pituitary :- Growth hormone, thyroid stimulating hormone THS or thyrotropin, adrenocoicotropin hormone ACTH, prolactin, follicle stimulating hormone FSH, leutinizing hormone LH.iii Posterior pituitary :- Antidiuretic hormone ADHvasopressin, oxytocin.iv Thyroid gland :- Calcitoninv Pancreas :- Insulin, glucagon.vi Parathyroid :- Parathormonevii Placenta :- Human chorionic gonadotropin HCG, Human somatomammotropin.viii Kidney :- Renin, erythropoietinix Hea :- Atrial natriuretic peptide ANPx Stomach :- Gastrinxi Small intestine :- Secretin, Cholecystokinin CCKxii Adipocytes LeptinSome of these peptide hormones are glycoproteins, i.e., they have sugar associated with proteins. Glycoprotein hormones are FSH, LH, TSH, human chorionic gonadotropin, erythropoietin.2 Steroid hormones Steroid hormones are : ?i Adrenal coex :- Coisol Glucocoicoids, Aldosterone mineralocoicoids.ii Gonads :- Testosterone, estrogen, progesterone.iii Kidney :- 1, 25 - Dihydroxycholecalciferol3 Amine hormones These hormones are derivatives of amino acid tyrosine. These hormones are : ?i Thyroid gland :- Thyroxine T4 and Triiodothyronine T3.ii Adrenal medulla :- Norepinephrine Noradrenaline, Epinephrine adrenalineiii Hypothalamus :- Dopamine or Prolactin inhibiting factor PIF. 