are releasing hormones lipophilic or hydrophilic
I. The lipophilic hormones (steroids and thyroid hormones) bind to nuclear receptor proteins, which function as ligand-dependant transcription factors. A. Some steroid hormones bind to cytoplasmic receptors, which then move into the nucleus. The release of posterior pituitary hormones is controlled by neuroendocrine reflexes. III. Secretions of the anterior pituitary are controlled by hypothalamic hormones that stimulate or inhibit these secretions. A. Hypothalamic hormones include TRH, CRH, GnRH, PIH, somatostatin, and a growth hormone-releasing-hormone. I. Hormones are chemicals that are secreted into the blood by endocrine glands. A. The chemical classes of hormones include amines, polypeptides, glycoproteins and steroids. B. Nonpolar hormones, which can pass through the cell membrane of their target cells, are called lipophilic hormones. II. Precursors of active hormones may be classified as either prohormones or prehormones. A. Prohormones are relatively inactive precursor molecules made in the endocrine cells. A) Hydrophilic hormones diffuse through the blood plasma more quickly than lipophilic hormones do. B)Hydrophilic hormones do not have to diffuse through the cytoplasm to bind to a nuclear receptor, as most lipophilic hormones do. C) Hydrophilic hormones activate (or inactivate) pre-existing proteins. Synthesis of new proteins is generally not required. D) Hydrophilic hormone molecules are generally smaller and thus can diffuse through the membrane of the target cell more quickly. Vasopressin/Antiduretic Hormone/ADH. hydrophilic, polypeptide non-tropic hormone produced by hypothalmus secreted by posterior pituitary increases H2O reabsorption within kidney tubules; causes vasoconstriction of blood vessels. 1 Hormones are chemicals that are secreted into the blood by endocrine glands. 2  The chemical classes of hormones include amines, polypeptides, glycoproteins and steroids. 3  Nonpolar hormones, which can pass through the cell membrane of their target cells, are called lipophilic hormones. Parathyroid Hormone/PTH. Hydrophilic, polypeptide non tropic hormone produced and secreted by parathyroid glands increases plasma concentration of Ca2+ by increasing calcium absorption within the intestines and kidneys and by releasing calcium from bones. • Lipophilic Hormones (Hydrophobic Hormones): •Hormones that are not soluble in aqueous medium, but soluble in lipid; •They can easily cross the cell membrane, •Thus, they can enter target cells and bind to intracellular receptors to carryout their action; •Examples: Thyroid hormones, Steroid hormones; Hypothalmic Releasing and Inhibiting Hormones. Hydrophilic, peptide hormones PIH is an amine/catecholamine tropic hormone produced and secreted by hypothalmus stimulate or inhibit secretion of anterior pituitary hormones anterior pituitary. hydrophilic, polypeptide non tropic hormone produced/secreted by alpha cells of the Islets of Langerhans of the endocrine pancreas increases the synthesis and release of glucose from glycogen stores (within liver) thus increasing blood glucose levels.
Hypothalamic hormones