Endocrinology

PANCREAS & ITS HORMONES PANCREAS ·      Pancreas in an organ that lies at the upper left abdomen. ·      Pancreas is made up of two major types of cells. ü Acini-which secretes digestive juice into the duodenum. ü Islets of Langerhans –which secretes hormones. (25%)α Islets of Langerhans – Glucagon. (60%)β Islets of Langerhans – Insulin. (15%)δ Islets of Langerhans – Somatostatin.        INSULIN: v Insulin is a protein hormone secreted by β cells of islets of Langerhans of pancreas.    Chemistry: v Molecular weight around 6000 Daltons. v It consist of 2 polypeptide chains-A chain & B chain. v A chain has 21 amino acids & B chain has 30 amino acids. v A chain & B chain are connected by 2 inter disulphide bridges at cysteine 7 of A chain and cysteine 7 of B chain and cysteine 20 of A chain and 19 of B chain. v ‘A’ chain has intra disulphide bridge between cys...

PARATHYROID GLAND:   o   There are 4 parathyroid glands in humans o      They are located immediately behind the thyroid gland o      Each gland is about 6mm long, 3mm wide and 2mm thick. o   It secretes parathormone (PTH) or Para thyroid hormone Parathyroid Hormone Or Parathormone Chemistry ü PTH is a linear polypeptide with 84 amino acids. ü Has 9500 Daltons mol. weight. ü N-terminal of PTH is Alanine C-terminal of PTH is Glutamine Synthesis ü PTH is synthesized in chief cells of Parathyroid gland. ü Initially it is synthesized as Pre Pro PTH with 115 amino acids from Polysomes adhered on RER. ü Before the formation of complete Pre Pro PTH, the N-terminal end protruding from lumen of ER is cleaved by signal peptidase hydrolyzing 25 amino acid and leaving Pro PTH with 90 amino acids. ü Pro PTH from ER moves to Golgi where Clipase enzyme cleaves 6 amino acid, thus converting Pro PTH to PTH with 84 amin...

THYROID GLAND o   Thyroid Gland is located immediately below the larynx on its either side and anterior to trachea. o   It weighs about 15-20gms o   Thyroid gland has number of follicles filled with colloid and lined by Cuboid epithelial cells. o   The major component of colloid is a large glycoprotein Thyroglobulin which contains the thyroid hormones within it. o   Thyroid gland secretes 2 major hormones Ø   Tetra-Iodo Thyronine(or) Thyroxine (or) T4 Ø   Tri-Iodo Thyronine(or)T3 THYROID HORMONES o   The principle hormones secreted by the follicular epithelial cells are T3 and T4 o   About 93% of metabolically active hormones secreted by thyroid gland is T4 and 7% are T3. o   T3 is more potent than T4 o   T3 has short half-life than T4 Chemistry o   Both Thyroxine and Tri Iodo thyronine are formed from Tyrosine of Thyroglobulin by Iodination. T3 (Tri Iodo thyronine) o   Molecular weight -65...