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working of endocrine system dr sangu.pptx
- 1. WORKING OF ENDOCRINE SYSTEM By, Dr. Sangu Malar Selvan.R 1st yr MD (CLINICAL YOGA) SDMCNYS, Ujire
- 2. CONTENTS • INTRODUCTION • ENDOCRINE ORGANS • MECHANISM OF HORMONE RELEASE • PITUITARY GLAND • THYROID GLAND • PARATHYROID GLAND • PINEAL GLAND • PANCREASE • GONADS • PINEAL,THYMUS,KIDNEYS,HEART • LOCAL HORMONES • REFERNCES
- 3. Introduction: • All the physiological activities of the body are regulated by two major system 1. Nervous system 2. Endocrine system • Endocrine system is a ductless glands that secret hormones • Hormones are “messenger molecules” • Circulate in blood • Act on distant target cells • Target cells respond to the hormones for which they have receptors • The effect are dependent on the programmed response of the target cells • Hormones are just molecule triggers
- 4. Basic categories of hormone • Amino acid based: modified amino acids peptides (short chain of amino acids) ,and proteins (long chain amino acids) secreted by pituitary gland, parathyroid gland ,pancreas and placenta. • Steroids : lipid molecule derived from cholesterol secreted by adrenal cortex, gonads and placenta. • Tyrosine derivatives: two types of hormones namely thyroid hormone and adrenal medullary hormones are derived from the amino acid tyrosine
- 5. Endocrine organs • Purely endocrine organs 1. Pituitary gland 2. Pineal gland 3. Thyroid gland 4. Parathyroid gland 5. Adrenal gland • Endocrine cells in other organs 1. Pancreas 2. Thymus 3. Gonads 4. hypothalamus
- 7. Important three endocrine gland
- 9. Anterior pituitary or adenohypophysis • Anterior pituitary is also known as Master gland because it regulates many other glands through its hormones. • It consists of 3 parts pars distalis, pars tuberalis, pars intermedia. • Regulations: • Hypothalamus controls anterior pituitary by secreting the releasing and inhibitory hormones, which are called neurohormones • Releasing and inhibitory hormones of hypothalamus are : GHRH, GHRP, GHIH, TRH, CRH, GnRH, PIH
- 10. Hormones secreted by anterior Pituitary 1. Growth hormone (GH)or somatotropic hormone(STH) 2. Thyroid stimulating hormone(TSH) 3. Adrenocorticotropic hormone(ACTH) 4. Follicle-stimulating hormone(FSH) 5. Luteinizing hormone(LH) in females and interstitial cell stimulating hormone(ICSH)in males 6. Prolactin 7. Melanocyte stimulating hormone
- 11. Growth hormone • Source of secretion Secreted by Somatotropes which are acidophilic cells of anterior pituitary • Chemistry ,blood levels and daily output • Protein in nature having single chain polypeptide with 191 AA • Molecular weight 21,500 • Basal level of GH in blood up to 300g/dL • Daily output : 0.5 to 1.0 mg • transport Transported in blood by GH-binding proteins • Half life and metabolism 20 min Degraded in liver and kidney • Actions of growth hormone • Responsible for general growth of the body • Hypersecretion leads to gigantism • Hypo secretion leads to dwarfism • Also acts on metabolism on carbohydrates ,proteins, lipids
- 12. . Thyroid stimulating hormone • Source of secretion Secreted by anterior pituitary gland • Chemistry ,blood levels and daily output Is a peptide with one alpha and one beta chain • Half life and plasma level Half life 60 min Plasma level 2 U/mL • Actions of TSH • Increases number of follicular cells of thyroid • Immediate effect of TSH is proteolysis of the thyroglobulin, by which thyroxine is released within 30 min • Mode of action Is by AMP mechanism
- 13. Adrenocorticotropic hormone(ACTH) • Source of secretion Secreted from anterior pituitary gland • Chemistry ,blood levels and daily output Single chain polypeptide with 39 AA Daily output- 10 ng Plasma level- 3ng/dL • Synthesis Synthesized from a protein called prepro- opiomelanocortin. • Half life and metabolism 30 min • Actions of ACTH It is necessary for the structural integrity and secretary activity of adrenal cortex
- 14. Follicle stimulating hormone(FSH) • Source of secretion • Secretes from anterior pituitary gland • Chemistry ,blood levels and daily output • Glycoprotein made up one alpha subunits(92 AA) and a beta subunits(118) • Half life and metabolism • 3 to 4 hours • Actions of growth hormone • In males acts along testosterone and accelerates the process of spermatogenesis • In females causes the development of graffian follicle from primordial follicle
- 15. Luteinizing hormone • chemistry • Glycoprotein made up of one alpha(92AA) subunit and one beta subunit(141AA) • Half life • 60 min • action • In male LH known as interstitial cell stimulating hormone because it simulates the interstial cells of leydig in testes • In females causes maturation of vesicular follicle into graffian follicle along with FSH • It is responsible for ovulation
- 16. Hyperactivity Hypo activity 1. Gigantism 2. Acromegaly 3. Acromegalic gigantism 4. Cushing disease 1. Dwarfism 2. Acromicria 3. Simmond disease
- 17. Posterior pituitary or neurohypophysis • Parts: 1. Pars nervosa 2. Neural stalk or infundibular stem 3. Median eminence • Hormones of posterior pituitary 1. Antidiuretic hormone(ADH) 2. oxytocin
- 18. Antidiuretic hormone • Source of secretion • Supraoptic nucleus of hypothalamus • Chemistry and half life • ADH is a polypeptide containing 9 AA • 18-20 min • actions 1. Retention of water 2. Vasopressor action • regulation • ADH secretion depends upon the volume of the body fluid and osmolality of the body fluids
- 19. oxytocin Source of secretion • Paraventricular nucleus of hypothalamus Chemistry and half life • Oxytocin is a polypeptide having 9 AA 6 min Actions in females 1. Action of oxytocin on mammary glands 2. Milk ejection reflex 3. Action on uterus 4. On pregnant uterus 5. On non pregnant uterus Action in males • The release of oxytocin increases during ejaculation • It facilitates the release of sperm into urethra by causing contraction of smooth muscles in reproductive tract Mode of action of oxytocin • Oxytocin acts on mammary gland and uterus by activating G-protein coupled oxytocin receptor
- 21. Synthesis of thyroid hormones • It takes place in thyroglobulin present in follicular cavity. • Iodine and tyrosine are essential for the formation of thyroid hormones • Iodine consumed through diet converted into iodide absorbed from GI tract • Tyrosine is also consumed through diet and absorbed from GI tract Storage of thyroid hormones • After synthesis the thyroid hormones remain in the form of vesicles within thyroglobulin and are stored for long period Transport: • - thyroxine binding globulin • -Thyroxine binding pre albumin • -albumin
- 22. Thyroxine and tri iodothyronine • chemistry Iodine containing derivatives if aminoacid thyrosine • Potency and Duration of action • The potency of T3 is four times more than T4 • T4 acts longer period than T3 • Duration of T4 action is four times more than T3 action • Half life • T3- 7 days • T4- vary between 10 to 24 hours • Rate of secretion • T4 =80-90 ug/day • T3= 4 to 5 ug/day • Plasma level • T3 0.12 ug/dL • T4 8 ug/ dL • Metabolism • Occurs in muscles liver and kidneys
- 23. calcitonin Source of secretion • Parafollicular cells situated among the follicle in thyroid gland Chemistry and synthesis • Calcitonin is a polypeptide chain with 32 AA • Molecular weight 3400 • Synthesized from procalcitonin Plasma levels and half life • Plasma level 1 to 2 ng/dL • Half life 5 to 10 min metabolism • Calcitonin is degraded and excreted by liver and kidneys
- 24. Functions of thyroid hormones 1. Action on basal metabolic rate 2. Action on protein metabolism 3. Action on carbohydrate metabolism 4. Action on fat metabolism 5. Action o plasma and liver fats 6. Action n vitamin metabolism 7. Action on body temperature 8. Action on growth 9. Action on body weight 10 . on blood 11.Action on CVS 12. Action on respiration 13. Action on GIT 14. Action on CNS 15. Action on skeletal muscle 16. Action on sleep 17. Action on sexual function 18. Action on other endocrine glands
- 25. Regulation Low BMR Leptin Melanocyte stimulating hormone Excess iodine intake Stress Somatostatin dopamine hypothalamus Thyrotropin releasing hormone Anterior pituitary TSH Thyroid gland T3/ T4 stimulation inhibition FEEDBACK INHIBITION
- 26. Disorders of thyroid gland 1. Hyperthyroidism 2. Hypothyroidism 3. goiter
- 30. Sex hormones
- 36. Catecholamine's • Half life is about 2 min. • Synthesized from AA tyrosine. • Metabolism- 85% are taken up by the sympathetic adrenergic neurons and 15% are degraded • Pheochromocytoma- condition due to hypersecretion of catecholamine 1. Adrenaline or epinephrine 2. Noradrenaline or norepinephrine 3. dopamine
- 40. Insulin Source of secretion • Secreted by B cells in the islets of Langerhans of pancreas Chemistry and half life • Polypeptide with 51 AA • Molecular weight – 5808 • Half life – 5 min Plasma level • 10 üU/mL synthesis • Preproinsulin to proinsulin • Proinsulin to insulin metabolism • Binding of insulin receptor is essential for removal from circulation and degradation • Degraded in liver and kidneys Actions of insulin • Increases transport and the uptake of glucose by the cells • Promotes peripheral utilization • Promotes glucogenesis • Inhibits glycogenolysis
- 41. Glucagon Source of secretion Secreted from A cell in islets of langerhans Chemistry and half life Glucagon is polypeptide contains 29 AA Molecular weight- 3485 Half life – 3 to 6 min synthesis Synthesized from preproglucagon Preproglucagon to proglucagon Proglucagon to glucagon metabolism Degraded in kidney and liver Action of glucagon Action of glucagon is antagonistic to those of insulin
- 45. REFERENCES • ESSENTIAL OF MEDICAL PHYSIOLOGY
- 46. THANK YOU