1 / 49

Basics of Endocrinology

Basics of Endocrinology. Hasan AYDIN , MD Yeditepe University Medical Faculty Endocrinology and Metabolism. Definitions. Endocrinology- the study of hormone and glandular abnormalities Hormones- biologically active substances secreted by glands

race
Download Presentation

Basics of Endocrinology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Basics of Endocrinology Hasan AYDIN, MD Yeditepe University Medical Faculty Endocrinology and Metabolism

  2. Definitions • Endocrinology- the study of hormone and glandular abnormalities • Hormones-biologically active substances secreted by glands • Endocrine- hormones that have a biological effect far away • Paracrine- hormones that have a biological effect nearby • Autocrine- hormones that have a local effect

  3. Endocrine System Neuroendocrine System Nervous System Secretory cell Neuron H H H Target

  4. Paracrine Actions • Paracrine-actions • sex steroids inthe ovary • angiotensin II in the kidney • platelet-derived growth factor released by platelets. • Juxtacrine actions • somehematopoietic growth factors

  5. Autocrine Action • Insulin released by the pancreatic islet B cells • Somatostatin can inhibit its own release from pancreatic D cells

  6. Hormones • Substances released by endocrine glands and transported through the bloodstream to tissues where they act to regulate specific functions. • These actions are mediated by binding of the hormone to receptor molecules. • Allosteric effectors that alter conformation of the receptors to which they bind.

  7. Functions of Hormones • Growth and development: Thyroid, GH, Sex Steroids, Cortisol • Reproduction: Estrogen, Testosterone, FSH, LH, Thyroid • Homeostasis: Thyroid, Cortisol • Changes in environment: Cortisol, Thyroid Aldosterone

  8. Hormones can interact with each other Gluco neo genesis Protein synthesis Temp Metab HR Organ growth Sex steroids T-4 GH Skeletal growth

  9. Hormone Classification • Proteins- TSH, insulin, PTH • Amino acids-thyroid hormones (T3 and T4), epinephrine • Steroids-cortisol, aldosterone, testosterone

  10. Mechanism of Action of Hormones • Circulate in blood stream bound to transporter proteins or free • Free hormone is the active hormone • Enter cells to alter biological activity

  11. I I I I Hormone Action: peptide and cathecolamines R TSH TSH TSH R 2nd messenger protein T-4 effect

  12. T-3 R R T-3 Hormone Action: Steroid, Thyroid T-3 TBG T-3 R T-3 Increased HR β-receptors

  13. Hormone Regulation • Feedback loops • Circadian rhythms • Receptor specificity • Receptor concentration

  14. Phenomenon of Negative Feedback

  15. Phenomenon of Positive Feedback

  16. Feedback Regulation of the Anterior Pituitary: Hypothalamus - - Short Loop Feedback - ? Long Loop Feedback + - Pituitary + Target Organ

  17. Feedback Mechanisms: Rhythms Circhoral rhythmsare ''about an hour,'' Circadian rhythms are ''about a day'' Circatrigantan rhythms are''about a month,'' Circannual rhythms are ''about ayear.'‘

  18. Endocrine Rhythms ACTH LH GH 0800 2000 0800 0800 2000 0800 0800 2000 0800 Cortisol TSH Testosterone 0800 2000 0800 0800 2000 0800 0800 2000 0800

  19. The Subunit Confers Specificity α- Subunit β - Subunits hCG LH TSH FSH

  20. Precursors of Hormones Precursor Type of compound Example of hormone Protein Growth hormone Peptide ACTH Protein Amino acid Thyroxine Cortisol Steroid Cholesterol 1,25 OHD3 Modified amino acid Epinephrine Tripeptide TRH Amino acid Retinoid Retinoic acid Eicosanoid Prostoglandin E1 Fatty acid

  21. Receptors

  22. Receptors • Cellular proteins that have bifunctional properties of both • Recognition • Signal activation

  23. Catecholamines Prostoglandins ACTH Glukagon PTH TSH LH Somatostatin Insulin GH TGF-b Receptors • Cell surface receptors:

  24. Receptors Nuclear receptors: • Steroid hormones • Vitamin D • Thyroid hormones • Retinoids

  25. Regulation of Responsiveness to Hormones Effector1 Effector2 Response Hormone Receptor ± ± ±

  26. Interaction Between Hormone Response System H1 R1 G1 E1 Range of Possible Pathways H2 R2 G2 E1

  27. Classification of Hormones: Types of Ligands: • Agonist • Antagonist • Partial agonist-partial antagonist • Mixed or Heterologous Agonists-Antagonists

  28. Classes of Hormone Action Glucocorticoid Agonist Cortisol Mineralocorticoid Progestin Partial agonist-antagonist Progesterone Glucocorticoid Mixed agonist-antagonist Estrogen Tamoxifen Estrogen Mineralocorticoid Spironolactone Antagonist Androgen

  29. Neuroendocrinology • Neurotransmitter • Synthesized in the cell body of the neuron • Travels down the axon • Stored in synaptic vesicles • Released upon depolarization • Mediates synaptic transsmission between two neurons • Paracrine action

  30. Nicotinic cholinergic Serotonergic Dopaminergic GABA Muscarinic Alfa 1 adrenergic Alfa 2 adrenergic Beta 1 adrenergic Beta 2 adrenergic Neurotransmitter Receptors

  31. Catecholamines TRH Dopamine CRH CGRH Somatostatin GnRH VIP Gastrin Secretin Cholecystokinin Neurotransmitter and Hormones

  32. Hypothalamic-Pituitary Relations • The hypothalamus regulates • temperature, • appetite, • thirst, • sexual behavior, • defensive reactions such as rage and fear, • body rhythms • The hypothalamus contains two types of neurosecretory cells • Neurohypophysial neurons traverse the hypothalamic-pituitary stalk and release vasopressin (ADH) and oxytocin from nerve endings in the posterior pituitary • Hypophysiotropic neurons release hormones into the median eminence and thence into the hypothalamic-pituitary vessels.

  33. Hypothalamic- Anterior Pituitary Relations • Stimulating hormones (releasing hormones) • TRH, • GnRH, • CRH, • GHRH, • Prolactin-releasing factorand • ADH • Inhibitory hormones • Somatostatin and • Dopamine.

  34. Precursor Phenomenon(Prehormones)

  35. Biosynthesis of Hormones: Precursors Pro-Opiomelanocortin (POMC) β-LPH N-Terminal Peptide ACTH LPH β-Endorphin α-MSH

  36. Bind to plasma protein Steroid Thyroid hormones Vitamin D GH Vasopressin Oxytocin Free Peptid hormones (ACTH, insulin, glucagon, PTH etc) Hormone Transport

  37. Regulation of the Endocrine System • Hormone concentration • Production rates • Delivery to the target tissue • Degradation • Freestanding

  38. Actions of Hormones • Developmental effects • Cell growth & cancer • Central nervous system effects • Effects on metabolism • Effects on cardiovascular & renal function • Effects on mineral & water metabolism • Effects on skeletal functions • Effects on reproductive function • Release of other hormones • Effects on immunologic functions

  39. Clinical Endocrinology • Hypofunction of a gland • Hyperfunction of a gland • Receptor defect • Second messenger defect

  40. Endocrine Hypofunction • Congenital defects in hormone biosynthesis • Autoimmune destruction of glands • Surgery or trauma to glands • Infiltration by tumors, infection

  41. Endocrine Hyperfunction • Hormone secreting pituitary tumor • End organ secreting tumor • Autoimmune disease • Inflammation/Infection • Iatrogenic/Facticious • Ectopic hormone secreting tumor

  42. Causes of Hypo or Hyperfunction

  43. Defects in Sensitivity to Hormones • Partial or complete resistance to the hormone • Secondary hormone hypersecretion

  44. Down-regulation

  45. Assessment of Glandular Activity • Measure the end organ hormone • Measure the pituitary regulating hormone • Suppression tests-to evaluate for hormone overactivity • Stimulation tests-to evaluate for underactivity • Imaging studies

  46. ThePlayers • Other endocrine organs • endothelial vascular cells • adipocytes • heart • bone • liver • kidney • ????

  47. Conclusions • Hormones are essential for normal growth, development, metabolism, energy, reproduction etc. • Hormones are tightly regulated by multiple systems • Both over and underproduction of hormones leads to clinical disease

More Related