The Endocrine System 1-3 (2024) PDF

WEEK 18 MPharm Programme Normal Systems The Endocrine System 1 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 The Endocrine System WEEK 18...

WEEK 18 MPharm Programme Normal Systems The Endocrine System 1 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 The Endocrine System WEEK 18 Outline of Lecture General principles of endocrine function Types of hormones & signalling pathways or mechanisms Broad divisions of the endocrine system The Central Endocrine Glands & their hormones The Peripheral Endocrine Glands & their hormones Slide 2 of 85 MPharm PHA115 The Endocrine System  Learning Outcomes WEEK 18 At the end of this lecture, you should be able to: Give a general description of the basic principles of endocrine signalling Describe the major divisions of the endocrine system Give a detailed account of the major hormones of the central endocrine glands & their actions Give a detailed account of the major hormones of the peripheral endocrine glands & their actions Predict what might happen during over- or under- secretion of the major hormones Slide 3 of 85 MPharm PHA115 The Endocrine System WEEK 18 General Principles of Endocrine Function Slide 4 of 85 MPharm PHA115 The Endocrine System  The Endocrine System WEEK 18 무관생 분비물을 , " 관을 통해 배출 X 직접혈류아 조직액으로부대 , Consists of specialised I ductless glands (and 내분비샘 = ) neurosecretory cells) scattered throughout body Ls Nevrous that seaetebrmonesntoblodlink e endocrane prodvce & nervous Clls) , allowaynenalguar tooguwn Glands/cells secrete biologically active chemical messengers (hormones) into the blood stream The hormones are carried in the blood stream to interact with distant target cells Interaction leads to specific target cell response in terms of metabolism, growth or reproduction Slide 5 of 85 MPharm PHA115 The Endocrine System  The Endocrine System WEEK 18 darkmes and ight thminmsponse carcadsamrhy to Niegulate pea - shaped endocrine systean , (세상하붕) located at base of braan. 체온 식욕조절 : 대사율 조절 ,. 호르몬 생성 regaulatly physalagical process 무신 s ortis. ,알도스테로 ,드드로렌분비 이 Slide 6 of 85 MPharm PHA115 The Endocrine System  The Endocrine System WEEK 18 Slide 7 of 85 MPharm PHA115 The Endocrine System  Functions of the Endocrine System WEEK 18 One of the body’s two major regulatory systems Regulates, integrates, coordinates & controls ^ important cellular, organ & body functions ~ Cellular metabolism, and water & electrolyte balance Cell growth, development and reproduction Adaptive changes to help the body cope with stressful situations Control & integration of the circulatory & digestive systems Slide 8 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Endocrine System Chemical Classification of Hormones Amines & Amino Acid derivatives NA, AD, DA, melatonin, T3 & T4 Polypeptides, Proteins & Glycoproteins TRH, ADH, GH, FSH, insulin Steroids – derived from cholesterol Cortisol, testosterone, estradiol, progesterone Hydrophilic vsoesiunis mplcatr. S Lipophilic hormones dissolue ablood ' Slide 9 of 85 MPharm PHA115 The Endocrine System  Synthesis & Transport of Hormones WEEK 18 Synthesis Vesicle-mediated pathway tormone peptide. Synthesised in rER & packaged in secretory vesicles polypeptide / protein hormones Non-vesicle-mediated pathway Synthesised in sER & directly released steroid hormones Transport kphphwilkfhrdisalma blid s freuabound. ~ Free & unbound – peptide hormones & amines _ Carrier protein-bound – steroid & thyroid hormones splophalic. Slide 10 of 85 MPharm Gspeesalket plasma PHA115 proten - The Endocrine System bendg topotein glubuinund suaually 」 WEEK 18 Synthesis & Transport of Hormones Slide 11 of 85 MPharm PHA115 The Endocrine System WEEK 18 Control of Hormonal Secretion 코티 bat ightPs peaksrstbefore gat Timing/Pattern of secretion Pulsatile or cyclical ' t before bettine Diurnal or circadian rhythm. Negative-feedback control 뇌하는체 End-product inhibition Slide 12 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hormonal Signalling Hormones produce their effects on target cells by interacting with specific receptors Target cell receptors are linked to specific effector systems in the cell ∞ Two broad types of hormonal receptors: Cell surface receptors < membrane outside f plasma -. Receptor-ion channels G-protein coupled receptors Tyrosine kinase-linked receptors Intracellular or kprophslic ≈ nuclear receptors Slide 13 of 85 MPharm PHA115 The Endocrine System  Endocrine Disorders WEEK 18 May result from: Hyposecretion JPobopiseaty! ∅ Endocrine gland secretes too little of its hormone 옮인 Primary, Secondary or Tertiary ? 함진중 ? Hypersecretion ∅ Endocrine gland secretes too much of its hormone Primary, Secondary or Tertiary Abnormal Target Cell Responsiveness Receptor down-regulation Receptor up-regulation Slide 14 of 85 MPharm PHA115 The Endocrine System  The Endocrine System WEEK 18 Two broad anatomical divisions The Central Endocrine Glands Hypothalamus Pituitary Gland Pineal Gland The Peripheral Endocrine Glands Thyroid glands Adrenal glands Endocrine pancreas Parathyroid glands The Gonads (ovaries & testes) Slide 15 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Central Endocrine Glands Slide 16 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Hypothalamus & Pituitary Gland Both located in the diencephalon Function cooperatively as ‘master regulators’ of the endocrine system  control of critical homeostatic & metabolic functions Both structures connected ( Enter , related ) 'are - blad netuork poun " l cpllay →Veinss rotlh by blood flow via the hypophysealO portal system cpillay (hypothalamus  anterior pituitary) 통부하기 apate portal ? ven via the hypothalamo-hypophyseal nerve tract (hypothalamus  posterior pituitary) Slide 17 of 85 MPharm PHA115 The Endocrine System  The Hypothalamus & Pituitary Gland WEEK 18 Slide 18 of 85 MPharm PHA115 The Endocrine System  The Hypothalamus & Pituitary Gland WEEK 18 Slide 19 of 85 MPharm PHA115 The Endocrine System WEEK 18 18 The Hypothalamus Brain’s coordinating centre for endocrine, behavioural & autonomic nervous system function Acts as neuroendocrine transducer or bridge receives & integrates multiple brain signals converts the electrical signals into chemical messages releases chemical messengers (hormones) to control secretion of pituitary hormones ? _ pituitary hormones MPharm MPH116 control the Normal Systems - Theactivity of peripheral Endocrine System ☆ ~ endocrine glands ? Slide 20 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hypothalamic Hormones Hormones That Regulate Anterior Pituitary Secretions ~ A( + ) Stimulatory Growth hormone-releasing hormone (GHRH) Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Inhibitory ( - ) θ Somatostatin (Growth hormone-inhibiting hormone; GHIH) ∞ Dopamine (Prolactin-inhibiting hormone; PIH) Slide 21 of 85 MPharm PHA115 The Endocrine System  Hypothalamic Releasing Hormones WEEK 18 Hypothalamus makes ^ ^ releasing hormones They are sent to the anterior pituitary The anterior pituitary releases its ~ stored tropic hormones into the systemic circulation They tell other endocrine organs in the body to grow & secrete their hormones Slide 22 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Major Hypothalamic Hormones Slide 23 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hypothalamic Hormones Hormones That Are Transported & Stored in The Posterior Pituitary Vasopressin or Antidiuretic hormone (ADH) Oxytocin Slide 24 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Pituitary Gland Hypophysis – located in diencephalon The ‘Master Gland’ – secretes hormones that control the function of many target glands & cells Consists of two anatomically & functionally distinct lobes Anterior pituitary (Adenohypophysis) Secretes & releases 6 major hormones Posterior pituitary (Neurohypophysis) ~ Stores & releases ? 2 hormones Slide 25 of 85 MPharm PHA115 The Endocrine System  The Pituitary Gland WEEK 18 시사상택 , & pineal gland prolactin연결 Slide 26 of 85 MPharm PHA115 The Endocrine System  The Pituitary Gland WEEK 18 Slide 27 of 85 MPharm PHA115 The Endocrine System WEEK 18 Anterior Pituitary Hormones secrete somatostatin. s Growth hormone (GH, somatotropin) ~ Primary hormone for regulation of overall body growth Stimulates growth of soft tissues & bone ( 연조직 & A여의 성장 촉진) Stimulates cell division & protein synthesis  tissue hyperplasia & hypertrophy ( 세포분화 인 한백질 합성 In Mumberof aals LS조렉비채쯤 s An Encraase En can fissme ~→ 이로밀해incaeasethewolemeo f organ or tessare dere to enlargencut of its compoment Lalls. ongan or Promotes cartilage & bone growth (in length & thickness) 관절 Growth-promoting effects are mediated via stimulated release of insulin-like growth factors (IGFs) or somatomedins by the liver gwoth prowty Hect IImtmtens. fr twe. Slide 28 of 85 MPharm PHA115 The Endocrine System  Anterior Pituitary Hormones WEEK 18 Growth hormone (cont’d) Important role in intermediary metabolism. Exerts largely anti-insulin effects Increases lipolysis   free fatty acid (FFA) mobilization & use as fuel 야기 " Inhibits peripheral cellular glucose uptake   blood glucose levels and  use of glucose as fuel Secretion modulated by GHRH & somatostatin from hypothalamus Ghrelin from gastric fundus Slide 29 of 85 MPharm PHA115 The Endocrine System  Functions of Growth Hormone WEEK 18 D ↑ adlescent somatostaton 지망력 Slide 30 of 85 MPharm PHA115 The Endocrine System WEEK 18 GH – Control of Release & Functions Igrowth hormones : s release groutlh lormones OTmottolamy ⑦ Slide 31 of 85 MPharm PHA115 The Endocrine System WEEK 18 MPharm Programme Normal Systems The Endocrine System 2 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 The Endocrine System WEEK 18 Anterior Pituitary Hormones Thyroid-stimulating hormone (TSH) Promotes vascularisation & growth of the thyroid gland Stimulates secretion of thyroid hormones Secretion stimulated by TRH from hypothalamus Adrenocorticotropic hormone (ACTH) Controls growth of the adrenal cortex Stimulates secretion of cortisol by adrenal cortex Secretion stimulated by CRH from hypothalamus Slide 33 of 85 MPharm PHA115 The Endocrine System WEEK 18 Anterior Pituitary Hormones Follicle-stimulating hormone (FSH) Stimulates growth & development of ovarian follicles (F) Promotes ovarian secretion of oestrogen (F) _ Required for sperm production (M) ① from the hypothalamus Secretion stimulated by GnRH hormones gonadotropiu- releassy Slide 34 of 85 MPharm PHA115 The Endocrine System WEEK 18 Anterior Pituitary Hormones prelease Luteinizing hormone (LH) Responsible for ovulation & development of the corpus luteum (F) Regulates ovarian secretion of sex hormones (F) Stimulates testes to secrete testosterone (M) α Secretion stimulated by GnRH from hypothalamus 여 Prolactin (PRL) Enhances breast development & milk production (F) _ i Secretion inhibited by sDA from hypothalamus dopamine Slide 35 of 85 MPharm PHA115 The Endocrine System  Anterior Pituitary Hormones WEEK 18 THK TEHI2 Slide 36 of 85 MPharm PHA115 The Endocrine System  뻥 WEEK 18 elease hormones Slide 37 of 85 MPharm PHA115 The Endocrine System WEEK 18 Posterior Pituitary Hormones 째 여경영 ‰ ypotkalamus - heur blood Eapallary IP Slide 38 of 85 MPharm PHA115 The Endocrine System WEEK 18 Posterior Pituitary Hormones lest name historical = decrease urine production 2 hormones Vasopress. bllod vessel 2. 7 loy tocin Vasopressin I samename. \ < → Antidiuretic hormone (ADH) Regulates urinary H2O loss & water balance in the body ancreasedsolukof blod get detydratim sgiay to louse waten. Promotes renal water re-absorption  regulation of plasma volume & osmotic pressure decrease s urineprodoctrom ☆ Oxytocin tormones s vey important Stimulates uterine contraction during childbirth & milk ejection during breast-feeding Secretion stimulated by birth canal & breast suckling reflexes Slide 39 of 85 MPharm PHA115 The Endocrine System  Posterior Pituitary Hormones WEEK 18 Slide 40 of 85 MPharm PHA115 The Endocrine System  → seaeete melatonar ahichinflrence , carcadsanhythm WEEK 18 pEneaalocytes synthessze cerebro spinalfluid, aalah Seasetson of formome s melatonan talees st dareatly anto into bluod daylight ,withlewelsflanctuatay Controllad The Pineal Gland [ doy & seasous. 출방울점 ) Tiny, pinecone-shaped gland – located in diencephalon Secretes melatonin – ‘hormone of darkness’ Fmelanin [피부관련 ) Production stimulated by suprachiasmatic nucleus (SCN) – body’s master ‘biological clock’ → circadian cyce [ 생체리듬 ] Main functions: Synchronizes body’s circadian rhythms with the 24-hr ‘day-night’ or ‘light-dark’ cycle 생체리듬 Promotes sleep Influences reproductive activity – onset of puberty Slide 41 of 85 MPharm PHA115 The Endocrine System  Pineal Gland & Melatonin Secretion WEEK 18 Slide 42 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Peripheral Endocrine Glands Slide 43 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Thyroid Gland Located in the neck, just below the larynx Voice box Two lobes of endocrine tissue joined in middle by narrow strip of gland (isthmus) rigut/ 연결하는 ≈ ( 1e가 pyramidal 부분 ) + lobe (thard lobe) from isthmus apwand extand Consists of 2 distinct secretory cell types Follicular cells Secrete two iodine-containing hormones Tetra-iodothyronine (T4 secreted ㅇ or thyroxine) s mostly t. Tri-iodothyronine ① (T3) actiuate form. ~ Parafollicular or C cells Secrete calcitonin (peptide hormone) ~ Slide 44 of 85 MPharm PHA115 The Endocrine System  The Thyroid Gland WEEK 18 장 이없 써나 !. fracheor. Calcstonn - calkiam omeostasis para alorgside 뜻! = Slide 45 of 85 MPharm PHA115 The Endocrine System WEEK 18 Thyroid Hormone Synthesis, Storage & Release (I-) τGB Formed from iodide & tyrosine. 책에 앉 e. Synthesis of tyrosine-containing thyroglobulin (TG) in ( TGB) YGB follicular cells & export into colloid. s release TGButo lumen offollicle , 2Is L2 Active uptake of iodide (I-) by follicular cells, oxidation (to ‘active’ iodide) & diffusion into colloid Attachment of iodide to tyrosine residues in TG  MIT & DIT π T Todothyoane 2 - hw dothyonme &Ds. Coupling of. - MIT & DIT  Tri-iodothyronine (T3) DIT & DIT  Tetra-iodothyronine (T4) T3 & T4 are attached to TG & stored in colloid until release nblood Slide 46 of 85 MPharm PHA115 The Endocrine System WEEK 18 Thyroid Hormone Synthesis, Storage & Release Release stimulated by TSH Endocytosis of synthesised TG-containing colloid by follicular cells Proteolytic digestion of TG to release T3 & T4 MIT & DIT Secretion / diffusion of T3 & T4 into blood & transportation in carrier (TBG)-bound form T4 converted to active T3 in the liver & kidneys Iodide removed from MIT & DIT and recycled Slide 47 of 85 MPharm PHA115 The Endocrine System WEEK 18 Thyroid Hormone Synthesis, Storage & Release I Slide 48 of 85 MPharm PHA115 The Endocrine System WEEK 18 Thyroid Hormone Synthesis, Storage & Release 건너뜀 ? Slide 49 of 85 MPharm PHA115 The Endocrine System WEEK 18 Functions of Thyroid Hormone Effect on Normal Growth & CNS Development Effects on normal growth mediated via GH & IGF-1 … Stimulates GH secretion & hepatic production of IGF-1 Promotes GH & IGF-1 effects on protein synthesis & skeletal growth Required for normal development of the nervous system in infants & children Promotes normal CNS activity in adults Slide 50 of 85 MPharm PHA115 The Endocrine System WEEK 18 Functions of Thyroid Hormone 고 Effect on Metabolic Rate & Heat Production Increases the overall basal metabolic rate & heat production (‘calorigenic effect’) main regulator of resting O2 consumption & energy expenditure Effect on Intermediary Metabolism Biphasic effects on carbohydrate, fat & protein metabolism Effect on Sympathetic Activity Increases cellular responsiveness to catecholamines via - receptor up-regulation   myocardial contractility & HR Slide 51 of 85 MPharm PHA115 The Endocrine System  TH – Control of Release & Functions WEEK 18 Slide 52 of 85 MPharm PHA115 The Endocrine System WEEK 18 Control of Thyroid Secretion Slide 53 of 85 MPharm PHA115 The Endocrine System  ∞ WEEK 18 The Adrenal Glands ‘Adrenal’ –e ‘next to the kidney’ Paired organs that cap the kidneys ^ Each consists of 2 distinct secretory organs: Aan outer adrenal cortex ≈ Secretes 3 types of steroid hormones ≈mamm I Mineralocorticoids (aldosterone) Glucocorticoids (cortisol) Sex hormones (Dehydroepiandrosterone, DHEA) O , an inner adrenal medullasympathetic neurons Secretes catecholamines – AD & NA Slide 54 of 85 MPharm PHA115 The Endocrine System  The Adrenal Glands WEEK 18 comprse 320Ma Slide 55 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Adrenal Cortex Consists of three layers or zones: Zona glomerulosa important , s is released ∞ Mineralocorticoids (aldosterone) Regulate Na+ & K+ balance & BP homeostasis Zona fasciculata s middle layer , Dnstres Glucocorticoids (cortisol) maagon tormone. Long-term control of metabolism Adaptation to stress Zona reticularis s secrete supplemeatal of sex fornones. Sex hormones (Dehydroepiandrosterone, DHEA) Supplement gonadal sex steroids Slide 56 of 85 MPharm PHA115 The Endocrine System WEEK 18 MPharm Programme Normal Systems The Endocrine System 3 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 The Endocrine System WEEK 18 The Adrenocortical Hormones Mineralocorticoids (aldosterone) essential for life maintain Na+ & K+ balance and ECF volume diumWater. & principal site of action is the distal & collecting tubules of the kidney promote Na+ retention & K+ excretion   fluid retention & expansion of ECF volume actions mediated via intracellular receptors secretion regulated by angiotensin II (RAAS), elevated serum K+ levels & ACTH (minor) Slide 58 of 85 MPharm PHA115 The Endocrine System WEEK 18 Control of Aldosterone Release Q Slide 59 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Adrenocortical Hormones fo Glucocorticoids (cortisol) - hotf propare trevtress involved in the regulation of carbohydrate, protein & fat metabolism  gluconeogenesis and  cellular glucose uptake and utilisation   blood glucose levels  protein synthesis and  protein catabolism in muscle   mobilisation of free amino acids  lipolysis   mobilisation & oxidation of free fatty acids play a key role in adaptation to stress exert anti-inflammatory & immunosuppressive effects entesiued gluco andetrs n. Slide 60 of 85 MPharm PHA115 The Endocrine System  Cortisol – Control of Release & Actions WEEK 18 Cortisol velease ⑦ - Hornone. ⑦ Iicoa F σ Slide 61 of 85 MPharm PHA115 The Endocrine System WEEK 18 The HPA Feedback System Ipitholamwo adendnitoy Slide 62 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Anti-inflammatory & Immunosuppressive Actions of Cortisol Slide 63 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Adrenocortical Hormones Sex hormones (‘androgenic’ DHEA) supplement sex hormones secreted by gonads exert minor effects on reproductive function physiologically significant in females Growth of pubic & axillary hair Enhancement of pubertal growth spurt Development & maintenance of female sex drive promote protein anabolism & growth Slide 64 of 85 MPharm PHA115 The Endocrine System WEEK The Adrenal Medulla Are 18 ? A modified sympathetic postganglionic neuron Innervated by preganglionic sympathetic axons arnmoffer Secretes el ' asrete 「 Adrenaline & Noradrenaline (& dopamine) Main functions Reinforce∞ “fight-or-flight” responses Maintenance of arterial blood pressure  heart rate, cardiac output & respiratory rate  glycogenolysis   glucose mobilisation  lipolysis   mobilisation of free fatty acids Slide 65 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Endocrine Pancreas Consists of clusters or ‘islands’ of secretory cells, called islets of Langerhans Comprise 3 types of secretory cells  (alpha) cells Secrete glucagon  (beta) cells Secrete insulin D (delta) cells Secrete somatostatin Secretions regulated by changes in blood glucose concentration Slide 66 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Pancreas & Secretory Cells Slide 67 of 85 MPharm PHA115 The Endocrine System  Pancreas Hormones WEEK 18 ☆ Insulin ∞ Important anabolic hormone – regulates fuel metabolism ~ Promotes cellular uptake & storage of glucose, fatty acids & amino acids   blood levels Enhances their conversion into glycogen, triglycerides & proteins glveose iglylyen storge furl - (  glycogenesis,  glycogenolysis & gluconeogenesis √ Jyuger sglverse  triglyceride synthesis and  lipolysis miscelprontk  protein synthesis and  protein degradation Effects mediated via insulin receptors (TK-linked) Slide 68 of 85 MPharm PHA115 The Endocrine System  Main Actions of Insulin WEEK 18 Slide 69 of 85 MPharm PHA115 The Endocrine System  Insulin – Control of Release & Actions WEEK 18 Incretontrothew ? Slide 70 of 85 MPharm PHA115 The Endocrine System WEEK 18 Pancreas Hormones Glucagon Canti - asulin ) Generally opposes actions of insulin Mobilizes energy-rich molecules from storage sites into blood stream   blood levels  glycogenesis,  glycogenolysis & gluconeogenesis   hepatic glucose production & release  lipolysis & ketogenesis,  triglyceride synthesis adpe fre. aid fottysynthesis and  protein degradation  protein Secreted in response to a direct effect of a fall in for blood glucose concentration blud yucan ad _. Slide 71 of 85 MPharm PHA115 The Endocrine System WEEK 18 Complementary Interactions of. Glucagon and insulin ⑦ 혈당인 , 혈상기 ≈ Slide 72 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hormones Involved in Calcium ∅ 、 Cast brre Homeostasis ^ symaln , fomatn. muscles. fun ateh. Parathyroid hormone (PTH) ☆ lveleased) lome frersastfer cean ,. Secreted by parathyroid glands (4 rice grain-sized glands ∞ located on dorsal surface of thyroid glands) Single most important regulator of blood Ca++ levels ([Ca++]) Raises plasma Ca++ levels via 3 mechanisms:  bone resorption   release of Ca++ into blood 「 ^ ∞  renal reabsorption of Ca++   blood [Ca++] ~  renal activation of vitamin D   intestinal absorption of : - Ca++   blood [Ca++] l "< , kidry ( apraea ' tay. Secretion regulated by blood Ca levels ++ Slide 73 of 85 MPharm PHA115 The Endocrine System  Regulation of Plasma [Ca++] by PTH WEEK 18 I Slide 74 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hormones Involved in Calcium Homeostasis ∞ ⑨ Vitamin D (cholecalciferol) 「 Synthesized by the skin & activated in the liver & 「 kidneys how to be actrated esseatially Supplemented by dietary intake Second most important regulator of blood [Ca++] Controls plasma Ca++ levels via 3 mechanisms:  intestinal absorption of Ca++   blood [Ca++]  bone resorption   release of Ca++ into blood  PTH synthesis Slide 75 of 85 MPharm PHA115 The Endocrine System WEEK 18 Activation & Actions of Vitamin D σ _ [ 화 Slide 76 of 85 MPharm PHA115 The Endocrine System WEEK 18 Actions & Interactions of PTH & Vit D Slide 77 of 85 MPharm PHA115 The Endocrine System WEEK 18 Hormones Involved in Calcium Homeostasis follaukcell θ Calcitonin parnf. Secreted by parafollicular or C cells of∞ ∞ thyroid gland 습 4 Exerts opposite effects to PTH Lowers plasma Ca++ levels via 2 mechanisms:  bone resorption   release of Ca++ into blood _  renal reabsorption of Ca++   blood [Ca++] … ++ plysait- gicall Minor physiological regulator of blood [Ca ] gulcth. Secretion regulated by blood Ca++ levels Slide 78 of 85 MPharm PHA115 The Endocrine System WEEK 18 Control of PTH & calcitonin secretion Slide 79 of 85 MPharm PHA115 The Endocrine System WEEK The Gonads - 18 The gonads are the sex organs, comprising the Testes – the male sex organ =□ Ovaries – the female sex organ I The primary functions of the testes include Production of sperm (spermatogenesis) Secretion of male sex hormones (androgens) – testosterone The primary functions of the Q ovaries include Production of ova or egg cells (oogenesis ) Secretion of female sex hormones – oestrogens & progestins/progestogens (progesterone) Slide 80 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Male Sex Hormones (Androgens) Testosterone bitgicdy cctie 그 h Secreted by Leydig cells of the testes actire for Converted into dihydrotestosterone (DHT) in target tissues Production increases rapidly at puberty Key functions: Promotes development of the male reproductive organs Promotes development & maintenance of male secondary sexual characteristics – facial hair, deeper voice, etc Increases & maintains sexual drive & desire Increases bone thickness & periosteal bone formation Increases basal metabolic rate & muscle mass Promotes RBC formation & protects against anaemia Slide 81 of 85 MPharm PHA115 The Endocrine System WEEK 18 Regulation of Testosterone Production Slide 82 of 85 MPharm PHA115 The Endocrine System WEEK 18 The Female Sex Hormones Oestrogens (Oestradiol) Secreted by granulosa cells of the ovarian follicle Production increases rapidly at puberty Key functions: [ Promotes maturation & maintenance of the reproductive organs in their mature functional state Promotes development & maintenance of female secondary sexual characteristics – breasts, pubic hair, fat distribution Plays critical roles, along with progesterone, in the normal female reproductive cycle (menstruation, pregnancy & childbirth) Reduces bone resorption & increases bone density Mediates important cardio- and vaso-protective effects Slide 83 of 85 MPharm PHA115 The Endocrine System  The Female Sex Hormones WEEK 18 Progestins/Progestogens (Progesterone) Secreted by granulosa & theca cells of the ovarian follicle Production increases markedly during the luteal phase Called the “hormone of pregnancy” Key functions: Plays critical roles, along with oestradiol, in the normal female reproductive cycle Helps mediate sexual response in the brain Prepares the uterus for implantation Renders cervical canal impenetrable to sperm after implantation Inhibits uterine contractions during gestation Inhibits Na+-retaining activity of aldosterone   natriuresis   fluid retention Slide 84 of 85 MPharm PHA115 The Endocrine System WEEK 18 Mean Sex Hormone Levels in Plasma in Males and Females Slide 85 of 85 MPharm PHA115 The Endocrine System