Hormones & Endocrine system - PowerPoint Presentation

1. Hormones & Endocrine systemMuthanna University-vet-medicine college physiology and chemistry department By Hayder Hussein

2. organic substances, produced in small amounts by specific tissues (endocrine glands), secreted into the blood stream to control the metabolic and biological activities in the target cells. Hormones may be regarded as the chemical messengers involved in the transmission of information from one tissue to another and from cell to cell.Secreted in very small amountsTransported, usually, in the bloodTarget cells have specific receptorsHormones 4/16/2017hayder hussein .. muthanna university

3. Behavioral EndocrinologyThe study of the relationship between hormones and behaviorHormones affect behavior and behavior feeds back to affect hormonesHormones↔Behavior Hayder H. ABED

4. The body’s slow chemical communication system; a set of glands that secrete hormones into the blood stream.The Endocrine System

5. Metabolism and tissue maturation.Ion regulation.Water balance.Immune system regulation.Heart rate and blood pressure regulation.Control of blood glucose and other nutrients.Control of reproductive functions.Uterine contractions and milk release.Functions of the Endocrine System

6. How Do Hormones Work?Hormones travel through the blood and influence the activity of other glands and organs. They produce short- and long-term changes in various cells and organs by acting like neurotransmitters at specific receptors. A hormone can only influence cells that have specific target receptors for that particular hormone.

7. CLASSIFICATION OF HORMONESI. Based on the chemical natureThe hormones can be categorized into threegroups considering their chemical nature.Peptides & Proteins: Most hormones are either peptides or proteins and are usually referred to as peptide hormones.Amines: Amine hormones are derivatives of the amino acid tyrosine. Lipids & Steroids: Steroid hormones are produced by the adrenal cortex and the gonads. 4/16/2017hayder hussein .. muthanna university

8. PolypeptidesSteroidsAmino acid derivativesInsulinglucagonsomatotropinFSHLHvasopressinOxytocinthyrotropinACTHEstrogentestosteronecortisolAldosteronecorticosteroneProgesteroneEpinephrinenorepinephrinedopamineThyroxine, T3 and T4MelatoninSerotoninHayder H. ABED

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10. CLASSIFICATION OF HORMONESII. Based on the mechanism ofactionHormones are classified into two broad groups (I and II) based on the location of the receptors to which they bind and the signals used to mediate their action.Group І Hormones that cannot pass through the plasma membrane.Group II Hormones that can pass through the plasma membrane.4/16/2017hayder hussein .. muthanna university

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12. Mechanism of action of group l hormonesThese hormones are lipophilic in nature and can easily pass across the plasma membrane.They act through the intracellular receptors located either in the cytosol or the nucleus.The hormone-receptor complex binds to specific regions on the DNA called hormone responsive element (HRE) and causes increased expression of specific genes.4/16/2017hayder hussein .. muthanna university

13. Mechanism of action of group ll hormonesThese hormones are considered as the first messengers. They exert their action through mediatory molecules, collectively called second messengers.4/16/2017hayder hussein .. muthanna university

14. Mechanism of action of group ll hormonesGroup I hormones are subdivided into three categories based on the chemical nature of the second messengers.(a) The second messenger is cAMP e.g. ACTH, FSH, LH, PTH, glucagon, calcitonin.(b) The second messenger is phosphatidylinositol/ calcium e.g. TRH, GnRH, gastrin, CCK.(c) The second messenger is unknown e.g. growth hormone, insulin, oxytocin, prolactin.4/16/2017hayder hussein .. muthanna university

15. cAMP—THE SECOND MESSENGERCyclic AMP (cAMP, cyclic adenosine 3`,5’-monophosphate) is a ubiquitous nucleotide. It consists of adenine, ribose and a phosphate (linked by 3’,5’ linkage). cAMP acts as a second messenger for a majority of polypeptide hormones. The membrane-bound enzyme adenylate cyclase converts ATP to cyclic AMP. cAMP is hydrolysed by phosphodiesterase to 5’-AMP .4/16/2017hayder hussein .. muthanna university

16. cAMP—THE SECOND MESSENGER Adenylate cyclase systemA series of events occur at the membrane level that influence the activity of adenylate cyclase leading to the synthesis of cAMP. This process is mediated by G-proteins, so designated due to their ability to bind to guanine nucleotides.4/16/2017hayder hussein .. muthanna university

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18. Hormones control the rates of many activities in the body.The rate at which each hormone secreted is controlled by a negative feedback mechanism.Three major patterns of regulation:Non-hormone substance (e.g. insulin)Stimulation by the nervous system (e.g. epinephrine)Hormone from another endocrine tissue (e.g. TRH, TSH) Control of Secretion RatesHayder H. ABED

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22. Hormones are dissolved in the blood plasma and transported in free form or bound to a protein carrier.As a result, hormones can be distributed throughout the body relatively quickly.Hormones diffuse from the capillary to the interstitial space.Transport and Distribution in the BodyHayder H. ABED

23. Small structure at the base of the brain Regulates many body functions, including appetite and body temperatureRegulates the pituitary glandThe HypothalamusHayder H. ABED

24. Seven releasing hormones are made in the hypothalamusThyrotropin-releasing hormone (TRH)Corticotropin-releasing hormone (CRH)Gonadotropin-releasing hormone (GnRH)Growth hormone-releasing hormone (GHRH)Growth hormone-release inhibiting hormone (GHIH)Prolactin-releasing factor (PRF)Prolactin-inhibiting hormone (PIH)Hypothalamic Releasing HormonesHayder H. ABED

25. Is influenced by emotionsCan be influenced by the metabolic state of the individualDelivered to the anterior pituitary via the hypothalamic-hypophyseal portal systemUsually initiates a three-hormone sequenceHypothalamus Releasing Hormones Secretion :Hayder H. ABED

26. Divided into a posterior and anterior portion.Posterior pituitary is also known as the neurohypophysis, because it is continuous with the brain.Anterior pituitary is also known as the adenohypophysis, because it acts more as a gland. Pituitary GlandHayder H. ABED

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29. This is called ‘the master gland’ as it produces at least 10 hormones which influence the other endocrine glands via the hypothalamus. It consists of two separate regions.The anterior pituitary and the posterior pituitary each share distinct connections with the hypothalamus.hypothalamusPosterior pituitaryVasopressin and oxytocinGH, ACTH, TSH, FSH, LH and prolactinAnterior pituitaryBlood supply

30. FSH (follicle stimulating hormone) LH (luteinizing hormone)The above two are called gonadotropinsTSH (thyroid stimulating hormone, thyrotropin)ACTH (adrenocorticotropic hormone)GH (growth hormone; somatotropin or somatotropic hormone) PRL (prolactin)Tropic (trophic) hormones-- target other endocrine glands to release their own hormones Hormones secreted by anterior pituitaryHayder H. ABED

31. 1.3.2.2-313 hormonal families of the anterior lobe: Table 2.1 (ALL proteins)

32. TSH– to stimulate the secretion of thyroid hormoneFSH & LH– important for the function of the testes and the ovariesFSH– growth of ovarian follicles and formation of spermLH (in women)– induce ovulation and the formation of the corpus luteum; stimulate the ovarian production of estrogen and progesteroneLH (in men)– stimulates the production of Testosterone; what cells?

33. 3-ACTH (adrenal corticotropic hormone) regulates hormone secretion by the cortex of the adrenal glands.4-Growth hormone (GH) is required for proper adult stature.Species specificity: primates for primate GH Metabolic effects5-Prolactin (PRL) is required for milk production in post-partum women. Hayder H. ABED

34. ADH (Antidiuretic Hormone)Target organ/tissue-- ? water retention, reduce urinealso functions as neurotransmitterOxytocinlabor contractions, lactation (milk ejection)possible role in sperm transport . . .emotional bondingposterior pituitary hormones Hayder H. ABED

35. Thyroid hormones diffuse through the target cell membrane.Thyroid hormones affect nearly every tissue in the body.Factors such as metabolism, growth, and maturation are affected.Thyroid Gland & HormonesHayder H. ABED

36. TRH & TSH help control thyroid hormone levels.Exposure to stress and cold increases TRH.Prolonged fasting decreases TRH.Regulation of Thyroid Hormone SecretionHayder H. ABED

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39. The Adrenal GlandsA pair of endocrine glands just above the kidneysIn common with the pituitary, adrenals are two glands with distinct embryological origins.Adrenal medullaAdrenal cortexBoth parts of the adrenals work together to regulate metabolism and stress.4/16/2017hayder hussein .. muthanna university

40. HORMONES OF ADRENAL CORTEXAs many as 50 steroid hormones (namely adrenocorticosteroids), produced by adrenal cortex, have been identified. However, only a few of them possess biological activity.Adrenocorticosteroids are classified into three groups according to their dominant biological action. However, there is some overlap in their functions.GlucocorticoidsMineralocorticoidsAndrogens and estrogens4/16/2017hayder hussein .. muthanna university

41. HORMONES OF ADRENAL MEDULLAAdrenal medulla is an extension of sympathetic nervous system. It produces two important hormones:Epinephrine (formerly adrenaline) Norepinephrine (formerly noradrenaline).Dopamine is another catecholamine, produced as an intermediate during the synthesis of epinephrine.These hormons are important neurotransmitters in the brain and autonomic nervous system.4/16/2017hayder hussein .. muthanna university

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43. HORMONES OF GONADSThe gonads (testes in males, ovaries in females) perform closely related dual functions.1. Synthesize sex hormones;2. Produce germ cells.The steroid sex hormones are responsible for growth, development, maintenance and regulation of reproductive system. Sex hormones are essentially required for the development of germ cells.4/16/2017hayder hussein .. muthanna university

44. HORMONES OF GONADSThe sex hormones are categorized into three groups1-Androgens or male sex hormones which are C-19 steroids.2. Estrogens or female sex hormones which are C-18 steroids. Ring A of steroid nucleus is phenolic in nature and is devoid of C-19 methyl group.3. Progesterone is a C-21 steroid produced during the luteal phase of menstrual cycle and also during pregnancy.Sex hormones are primarily responsible for growth, development, maintenance and regulation of reproductive system.4/16/2017hayder hussein .. muthanna university

45. Testosterone and MarriageHayder H. ABED

46. GASTROINTESTINAL (OR GUT) HORMONESThe digestion and absorption of nutrients is a complicated process which is regulated by the autonomic nervous system. This occurs in association with peptide hormones of gastrointestinal tract (GIT).1. Gastrin :It stimulates the secretion of gastric HCI and pepsinogen (proenzyme of pepsin).2. Secretin : Secretin stimulates pancreatic cells to produce bicarbonate (HCO3 – ) in order to neutralize HCI in duodenum.3. Cholecystokinin (CCK) : It stimulates the contraction of gall bladder and increases the flow of bile into duodenum. It also promotes the secretion of digestive enzymes and HCO3 – from pancreas.

47. Other hormones Besides the hormones discussed above, there are a few other important hormones which are not referred to in this lecture . Home work :Write short acounts about following hormones :Insulin and glucagon parathyroid hormone and calcitonin4/16/2017hayder hussein .. muthanna university

48. Thank you for listening 4/16/2017hayder hussein .. muthanna university