Function of Tyroxin

Functions of Thyroxin: The thyroid hormone emulates the heat production in body. On consumption, basal metabolic rate increases. It helps in maintaining normal body temperature. It also helps in increase in cellular metabolism like carbohydrate metabolism, protein metabolism, lipid metabolism etc. The thyroid hormone along with growth hormone & insulin helps in overall body growth. The thyrocalcitonin which is released from parafollicular cell or C-cell controls the calcium & phosphorus content in the body fluid & it helps in lowering of Ca ion in the body. Diagnosis/Clinical Action: Hyperthyroidism: - It is also known as exophthalmic goiter or Grave's disease. - Thyroid gland increases in its size. Hypothyroidism: This leads to Grave's disease which is an autoimmune disease in which an antibody produce against the TSH receptor (Thyroid Stimulating Hormone globulin - TSIG). Pancrease: The pancreas plays both exocrine and endocrine function, situated below stomach near duodenum. It is a leaf like structure, the exocrine part is mainly meant for the digestive purpose while the endocrine part is meant for different hormones secretion like insulin, glucagon, pancreatic polypeptides & somatostatin. Among these four hormones the insulin & glucagon are major hormones secreted - almost 90% of the endocrine cells. Pancrease: The endocrine part of pancreas contains four types of cells: α-cell, β-cell, δ-cell & F cell. These cells are present in endocrine part and known as islets of Langerhans, while the cells present in endocrine part are known as pancreatic acini. The exocrine part of pancreas is highly vascularized. Islets of Langerhans α-Cells β-Cells δ-Cells F-Cells Pancreatic Hormones endocrine α-Cells secrete glucagon (20%) pars β-Cells secrete Insulin (70%) δ-Cells secrete somatostatin (8%) F-Cells secrete pancreatic polypeptide (1%) Insulin: → Insulin was isolated from the islets of Langerhans of pancreas in 1922 by Banting & Best. → It consists of 2 polypeptide chains i.e. A chain of 21 amino acids & B-chain of 30 amino acids. → Both A & B chains are joined together by the C-chain & present in the form of preproinsulin in ER. → After removal of signal peptide, the preproinsulin is converted into proinsulin in ER, then the A & B chains are joined together by disulfide linkage to finally the removal of C-chain produce the insulin. Synthesis of Insulin: Preproinsulin | Signal peptide | B C A | B C A | B A | B A | Insulin Function of Insulin: The insulin have the half life of about 6 minutes. Normally it is responsible for body glucose metabolism that means in high blood sugar level it normalizes the blood glucose. Normally histamine condition the muscle membrane is slightly permeable to glucose, except the skeletal muscle which is stimulated by insulin. The insulin receptors are present in liver, skeletal muscle & adipose tissue. In liver after binding of insulin, the liver cell stop the process of gluconeogenesis. Functions of Insulin: → The normal blood sugar level in fasting condition varies from 80-120 mg/100 ml of blood. After taking food, it increases up to 120-180 mg/100 ml of blood. But after the intake of ordinary food, it may exceed up to 300-350 mg/100 ml of blood. This high blood sugar is maintained by insulin. In fast Metabolism: → Insulin promotes the fat metabolism that means more of the fatty acids are converted in liver from triglycerides (storage fat). → The insulin along with GH & thyroxin promotes the overall growth of the body.