The EndocrineThe EndocrineSystemSystem
Endocrine HistoryClaude Bernard (mid 1800s)pancreas, liverbrain, smooth ms.internal environA.A. Berthold (1849)reproductiv...
Endocrine HistoryCharles Brown-Sequard (1889)Harvard 1864-1868M.D. in NY 1873-1878bull testis extracts
Important PhysiologistsWalter Cannonhomeostasissympathetic nervous systemBodily Changes in Hunger, Fear, and Rage
Overview of the Endocrine System System of ductless glands that secretehormones Hormones are “messenger molecules” Circ...
HormoneTypes:•peptide or protein = at least 3 amino acids• peptides (short chains of amino acids), and proteins (longchain...
7Endocrine Organs Purely endocrine organs Pituitary gland Pineal gland Thyroid gland Parathyroid glands Adrenal: 2 g...
Mechanismsof hormonerelease(a) Humoral: in response to changinglevels of ions or nutrients in the blood(b) Neural: stimula...
Control of Endocrine FunctionA. PositiveB. or NegativeFeedbackmechanismsSelf-regulating system
STIMULUSHypothalamusReleasing Hormone(Release-InhibitingHormone)PituitaryStimulatingHormoneGlandHormoneTarget
Positive Feedback• Not common• Classic example:• Action ofOXYTOCIN onuterine muscleduring birth.
Positive Feedback• Baby pushes on cervix• Nervous signal to Hypothalamus• Hypothal. manufactures OXY• OXY transported to P...
Negative Feedback• Most commoncontrol mechanism• Level of hormone inblood or body’sreturn tohomeostasis shutsoff loop athy...
Negative Feedback: Thyroid
Basic Structure of FeedbackLoop• Environmental Stimulus• Stimulates Control Center (Brain-hypothal.)• Hypothalamic hormone...
16Hypothalamic Hormomes• Release Inhibiting Hormones• Somatostatin• Prolactin release inhibiting hormone-PIH• Releasing Ho...
17Number of Receptors• Down-regulation: is the decrease ofhormone receptors which decreasesthe sensitivity to that hormone...
Pituitary__________(hypophysis)Hypothalamus___________Hypothalamus__Anterior pituitary__(adenohypophysis)_____________Post...
Hypothalamus (general)Connection to pituitaryNeuronal to POSTERIORPITUITARYEndocrine to ANTERIORPITUITARYRH = Pituitary re...
Two divisions: Anterior pituitary(adenohypophysis) Posterior pituitary(neurohypophysis)Sits in hypophyseal fossa: depres...
What the letters stand for… TSH: thyroid-stimulating hormone ACTH: adrenocorticotropic hormone FSH: follicle-stimulatin...
Hypothalamus controls anterior pituitaryhormone release Releasing hormones (releasing factors)Secreted like neurotransmit...
What the letters mean… Releasing hormones (releasing factors) of hypothalamusTRH (thyroid releasing hormone) -----turns o...
So what do the pituitary hormones do? TSH stimulates the thyroid to produce thyroidhormone ACTH stimulates the adrenal c...
The others from the anterior pituitary… GH (aka somatrotropic hormone)stimulates growth of skeletal epiphysealplates and ...
26From the posterior pituitary (neurohypophysis)structurally part of the brain ADH (antidiuretic hormone AKA vasopressin)...
Anterior Pituitary HormonesHORMONE TARGET FUNCTIONThyroid (TSH)StimulatingThyroid gland TH synthesis &releaseGrowth (GH) M...
28Pituitary__________(hypophysis)Hypothalamus___________Now try and remember the anatomy
29The Thyroid Gland Anterior neck on tracheajust inferior to larynx Two lateral lobes and anisthmus Produces two hormon...
30 Thyroid is composed of spherical follicles Follicle cells: produce thyroglobulin, theprecursor of thryoid hormone (th...
Transportation of T.hormones Thyroxine binding globuline Thyroxine binding prealbumine Albumine (one tenth)31
32Some Effects of Thyroid Hormone(Thyroxine) Increases the basal metabolic rate The rate at which the body uses oxygen t...
 Increases RBC production Promotes growth Increases heart rate Increases rate and force of respiration Increases the ...
RegulationIncreases Low basal metabolic rate Leptin Alfa melanocytestimulating hormoneDecreases Excessive iodide intak...
35The Effects of Calcitonin Secreted from thyroid parafollicular (C)cells when blood calcium levels are high Calcitonin ...
36The Parathyroid Glands Most people have four On posterior surface ofthyroid gland(sometimes embedded)
37Parathyroids(two types of cells) Rare chief cells Abundant oxyphil cells(unknown function) Chief cells produce PTH P...
38Function of PTH(parathyroid hormone or “parathormone”) Increases blood Ca++ (calcium)concentration when it gets too low...
Regulation Increase in blood ca+ levels decreasesPTH secretion Excessive ca+ in diet Increases vit D synthesis Increas...
Importance of ca+ Bone and teeth formation Neuronal activity Skeletal muscle activity Cardiac activity Smooth muscle ...
41Adrenal (suprarenal) glands(“suprarenal” means on top of the kidney) Each is really two endocrine glands Adrenal corte...
42Adrenal Gland Adrenal cortex Secretes lipid-based steroid hormones, called“corticosteroids” – “cortico” as in “cortex”...
Transport Mineralocorticoids-globuline Glucocorticoids-Glucocorticoids bindingglobuline Around 6% flows freely in plasm...
Fate of corticosteroids Degraded in liver 25% 0f corticosteroids are excreted in bileand feces Remaining 75% in urin44
Mineralocorticoids Act on minerals particularly sodium andpotassium Those are Aldosteron 11-deoxycorticosterone Secre...
46Aldosterone, the main mineralocorticoid Secreted by adrenal cortex in response toa decline in either blood volume or bl...
Function Increases reabsorption of sodium (renaltebules & sweat gland) Increases in ECF volume Increases potassium excr...
Regulation Increase potassium conc. In ECF Decrease sodium conc. In ECF Decreases in ECF volume Adrenocorticotropic ho...
Glucocorticoids Mainly work on glucose metabolism Secreted from zona faciculata Three of them Cortisol Corticosterone...
50Cortisol, the most important glucocorticoid(Glucocorticoid receptors are found in the cells of most vertebrate tissues)...
Cont… Mobilization of fatty acid from adiposetissue Increases the utilization of fat as energy Blood ca++ levels decrea...
Cont… Needed for normal functioning of CNS Increases the resistance to stress It has a anti-inflamatory effect Prevent...
53Cortisol, continued Keeps blood glucose levels high enough to supportbrain’s activity Forces other body cells to switc...
54Hormonal stimulation of glucocorticoidsHPA axis (hypothalamic/pituitary/adrenal axis) With stress, limbic system is sti...
55 Steroid-secreting cellshave abundant smoothER As opposed to rough ERin protein-secreting cells Steroids directly dif...
Sex hormones Secreted from Zona Reticularis Androgens (male sex hormones) Dehydroepiandrosterone (most activated) Andr...
57Adrenal medulla Part of autonomicnervous system Spherical chromaffincells are modifiedpostganglionicsympathetic neuron...
Adrenaline & Noradrenaline Two types of receptor Alpha adrenargic hormone Beta adrenargic hormone Increases oxygen con...
Cont… Increases heart rate Increases force of contraction of the heart Increases conductivity of cardiac muscle Causes...
Cont… Increases glycogenolysis Causes vasodilatation in skeletal muscle Enhances cortical arousal Increases salivary s...
Dopamine Secrated by adrenal medula Also secretion by dopaminargic neuronsof basal ganglia Almost same action as noradr...
62The PancreasExocrine and endocrine cells Acinar cells (forming most of the pancreas) Head and body Exocrine function...
63Pancreatic isletendocrine cellsAlpha cells: secrete glucagonraises blood sugarmostly in peripheryBeta cells: secrete ins...
Insuline Antidiabetic hormone Increases transport and uptake of glucose Promote peripheral utilization of glucose Prom...
Regulation When blood sugar levels goes up Excess amino acid in blood By secretion of gastric hormones likegastrin,secr...
Glucagon Increases glycogenolysis in liver Increases blood sugar levels Inhibits secretion of gastric juices Increases...
RegulationIncreases Exercise stress Gastrin Cortisol cholicystokinindecreases Somatostatin Insuline Free fatty aci...
68The Gonads (testes and ovaries)main source of the steroid sex hormones Testes Interstitial cells secrete androgens Pr...
69The Pineal Gland At the end of a short stalk on the roof ofthe diencephalon Pinealocytes with dense calcium particles...
70Endocrine cells in various organs The heart: atrial natriuretic peptide (ANP) Stimulates kidney to secrete more salt ...
71Endocrine cells in various organs continued The placenta secretes steroid and protein hormones Estrogens, progesterone...
Thank you…72
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Endocrinology

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Endocrinology

  1. 1. The EndocrineThe EndocrineSystemSystem
  2. 2. Endocrine HistoryClaude Bernard (mid 1800s)pancreas, liverbrain, smooth ms.internal environA.A. Berthold (1849)reproductive hormones andbehavior
  3. 3. Endocrine HistoryCharles Brown-Sequard (1889)Harvard 1864-1868M.D. in NY 1873-1878bull testis extracts
  4. 4. Important PhysiologistsWalter Cannonhomeostasissympathetic nervous systemBodily Changes in Hunger, Fear, and Rage
  5. 5. Overview of the Endocrine System System of ductless glands that secretehormones Hormones are “messenger molecules” Circulate in the blood Act on distant target cells Target cells respond to the hormones for which theyhave receptors The effects are dependent on the programmedresponse of the target cells Hormones are just molecular triggers
  6. 6. HormoneTypes:•peptide or protein = at least 3 amino acids• peptides (short chains of amino acids), and proteins (longchains of amino acids)•steroid = derived from cholesterol•amine = derived from single amino acids(tryptophan, tyrosine)
  7. 7. 7Endocrine Organs Purely endocrine organs Pituitary gland Pineal gland Thyroid gland Parathyroid glands Adrenal: 2 glands Cortex Medulla Endocrine cells in otherorgans Pancreas Thymus Gonads Hypothalamus
  8. 8. Mechanismsof hormonerelease(a) Humoral: in response to changinglevels of ions or nutrients in the blood(b) Neural: stimulation by nerves(c) Hormonal: stimulation received fromother hormones
  9. 9. Control of Endocrine FunctionA. PositiveB. or NegativeFeedbackmechanismsSelf-regulating system
  10. 10. STIMULUSHypothalamusReleasing Hormone(Release-InhibitingHormone)PituitaryStimulatingHormoneGlandHormoneTarget
  11. 11. Positive Feedback• Not common• Classic example:• Action ofOXYTOCIN onuterine muscleduring birth.
  12. 12. Positive Feedback• Baby pushes on cervix• Nervous signal to Hypothalamus• Hypothal. manufactures OXY• OXY transported to POSTERIORPITUITARY & released• OXY stimulates uterine contraction• Loop stops when baby leaves birth canal
  13. 13. Negative Feedback• Most commoncontrol mechanism• Level of hormone inblood or body’sreturn tohomeostasis shutsoff loop athypothalamus andpituitary
  14. 14. Negative Feedback: Thyroid
  15. 15. Basic Structure of FeedbackLoop• Environmental Stimulus• Stimulates Control Center (Brain-hypothal.)• Hypothalamic hormones stim. Pituitary• Pituitary hormone stim. Target area• Target area produces change• Change acts negatively or positively on thecycle.
  16. 16. 16Hypothalamic Hormomes• Release Inhibiting Hormones• Somatostatin• Prolactin release inhibiting hormone-PIH• Releasing Hormones• Thyrotropin releasing hormone-TRH• Growth hormone releasing hormone-GHRH
  17. 17. 17Number of Receptors• Down-regulation: is the decrease ofhormone receptors which decreasesthe sensitivity to that hormone• Up-regulation: is the increase in thenumber of receptors which causes thecell to be more sensitive to a particularhormone
  18. 18. Pituitary__________(hypophysis)Hypothalamus___________Hypothalamus__Anterior pituitary__(adenohypophysis)_____________Posterior pituitary(neurohypophysis)Learn the 3 endocrine organs on this slide:HypothalamusPituitary (hyophysis)Pineal
  19. 19. Hypothalamus (general)Connection to pituitaryNeuronal to POSTERIORPITUITARYEndocrine to ANTERIORPITUITARYRH = Pituitary releasing hormonesRIH = Pituitary release inhibitinghormones
  20. 20. Two divisions: Anterior pituitary(adenohypophysis) Posterior pituitary(neurohypophysis)Sits in hypophyseal fossa: depression in sella turcica ofsphenoid bonePituitary secretes 9 hormonesThe Pituitary1. TSH2. ACTH3. FSH4. LH5. GH6. PRL7. MSH8. ADH (antidiuretic hormone), or vasopressin9. Oxytocin_________________________________________________________________The first four are “tropic”hormones, they regulate thefunction of other hormones________
  21. 21. What the letters stand for… TSH: thyroid-stimulating hormone ACTH: adrenocorticotropic hormone FSH: follicle-stimulating hormone LH: luteinizing hormone GH: growth hormone PRL: prolactin MSH: melanocyte-stimulating hormone ADH: antidiuretic hormone Oxytocin
  22. 22. Hypothalamus controls anterior pituitaryhormone release Releasing hormones (releasing factors)Secreted like neurotransmitters from neuronal axonsinto capillaries and veins to anterior pituitary(adenohypophysis)TRH-----turns on TSHCRH-----turns on ACTHGnRH (=LHRH)---turns on FSH and LHPRF-----turns on PRLGHRH----turns on GH Inhibiting hormonesPIF-----turns off PRLGH inhibiting hormone ---turns off GH
  23. 23. What the letters mean… Releasing hormones (releasing factors) of hypothalamusTRH (thyroid releasing hormone) -----turns on* TSHCRH (corticotropin releasing hormone) -----turns on ACTHGnRH (gonadotropin releasing hormone) ---turns on FSH and LHPRF (prolactin releasing hormone) -----turns on PRLGHRH (growth hormone releasing hormone) ----turns on GH Inhibiting hormones of hypothalmusPIF (prolactin inhibiting factor) -----turns off PRLGH (growth hormone) inhibiting hormone ---turns off GH
  24. 24. So what do the pituitary hormones do? TSH stimulates the thyroid to produce thyroidhormone ACTH stimulates the adrenal cortex to producecorticosteroids: aldosterone and cortisol FSH stimulates follicle growth and ovarianestrogen production; stimulates spermproduction and androgen-binding protein LH has a role in ovulation and the growth of thecorpus luteum; stimulates androgen secretion byinterstitial cells in testesThe four tropic ones regulate the function of other hormones:
  25. 25. The others from the anterior pituitary… GH (aka somatrotropic hormone)stimulates growth of skeletal epiphysealplates and body to synthesize protein PRL stimulates mammary glands in breastto make milk MSH stimulates melanocytes; mayincrease mental alertness
  26. 26. 26From the posterior pituitary (neurohypophysis)structurally part of the brain ADH (antidiuretic hormone AKA vasopressin)stimulates the kidneys to reclaim more waterfrom the urine, raises blood pressure Oxytocin prompts contraction of smoothmuscle in reproductive tracts, in femalesinitiating labor and ejection of milk frombreasts
  27. 27. Anterior Pituitary HormonesHORMONE TARGET FUNCTIONThyroid (TSH)StimulatingThyroid gland TH synthesis &releaseGrowth (GH) Many tissues growthAdrenocortico-Tropin (ACTH)Adrenal cortex Cortisol release(androgens)Prolactin (Prl) Breast Milk productionFollicle (FSH) Gonads Egg/sperm prod.Luteinizing(LH)Gonads Sex hormones
  28. 28. 28Pituitary__________(hypophysis)Hypothalamus___________Now try and remember the anatomy
  29. 29. 29The Thyroid Gland Anterior neck on tracheajust inferior to larynx Two lateral lobes and anisthmus Produces two hormones Thyroid hormone:tyrosine based with 3 or 4iodine molecules T4 (thyroxine) and T3 Calcitonin involved withcalcium and phosphorusmetabolism
  30. 30. 30 Thyroid is composed of spherical follicles Follicle cells: produce thyroglobulin, theprecursor of thryoid hormone (thyroxin) Colloid lumen is of thyroglobulin Parafollicular “C” cells: produce calcitonin
  31. 31. Transportation of T.hormones Thyroxine binding globuline Thyroxine binding prealbumine Albumine (one tenth)31
  32. 32. 32Some Effects of Thyroid Hormone(Thyroxine) Increases the basal metabolic rate The rate at which the body uses oxygen to transformnutrients (carbohydrates, fats and proteins) intoenergy Affects many target cells throughout the body;some effects are Protein synthesis Bone growth Decrease blood ca+ levels Neuronal maturation Cell differentiation
  33. 33.  Increases RBC production Promotes growth Increases heart rate Increases rate and force of respiration Increases the appetite Increases secretion of digestivehormones Essential for normal sexual function Increases the demand of other hormones33
  34. 34. RegulationIncreases Low basal metabolic rate Leptin Alfa melanocytestimulating hormoneDecreases Excessive iodide intake Stress Somatostatin Glucocorticoids Dopamine34
  35. 35. 35The Effects of Calcitonin Secreted from thyroid parafollicular (C)cells when blood calcium levels are high Calcitonin lowers Ca++ by slowing thecalcium-releasing activity of osteoclasts inbone and increasing calcium secretion bythe kidney Acts mostly during childhood
  36. 36. 36The Parathyroid Glands Most people have four On posterior surface ofthyroid gland(sometimes embedded)
  37. 37. 37Parathyroids(two types of cells) Rare chief cells Abundant oxyphil cells(unknown function) Chief cells produce PTH Parathyroid hormone, orparathormone A small protein hormone
  38. 38. 38Function of PTH(parathyroid hormone or “parathormone”) Increases blood Ca++ (calcium)concentration when it gets too low Mechanism of raising blood calcium1. Stimulates osteoclasts to release more Ca++ frombone2. Decreases secretion of Ca++ by kidney3. Activates Vitamin D, which stimulates the uptake ofCa++ from the intestine Has opposite effect on calcium ascalcitonin (which lowers Ca++ levels)
  39. 39. Regulation Increase in blood ca+ levels decreasesPTH secretion Excessive ca+ in diet Increases vit D synthesis Increases reabsorption of ca+ from bones39
  40. 40. Importance of ca+ Bone and teeth formation Neuronal activity Skeletal muscle activity Cardiac activity Smooth muscle activity Secretary activity of glands Cell division and growth Coagulation of blood40
  41. 41. 41Adrenal (suprarenal) glands(“suprarenal” means on top of the kidney) Each is really two endocrine glands Adrenal cortex (outer) Adrenal medulla (inner) Unrelated chemicals but all help with extreme situations
  42. 42. 42Adrenal Gland Adrenal cortex Secretes lipid-based steroid hormones, called“corticosteroids” – “cortico” as in “cortex” MINERALOCORTICOIDS– Aldosterone is the main one GLUCOCORTICOIDS– Cortisol (hydrocortisone) is the main one Sex hormones Adrenal medulla Secretes epinephrine, norepinephrine anddopamine
  43. 43. Transport Mineralocorticoids-globuline Glucocorticoids-Glucocorticoids bindingglobuline Around 6% flows freely in plasma Sex hormones-Sex hormones bindingglobuline43
  44. 44. Fate of corticosteroids Degraded in liver 25% 0f corticosteroids are excreted in bileand feces Remaining 75% in urin44
  45. 45. Mineralocorticoids Act on minerals particularly sodium andpotassium Those are Aldosteron 11-deoxycorticosterone Secreted from zona glomerulosa Half life – 20mins Life saving hormone45
  46. 46. 46Aldosterone, the main mineralocorticoid Secreted by adrenal cortex in response toa decline in either blood volume or bloodpressure (e.g. severe hemorrhage) Is terminal hormone in renin-angiotensinmechanism Prompts distal and collecting tubules inkidney to reabsorb more sodium Water passively follows Blood volume thus increases
  47. 47. Function Increases reabsorption of sodium (renaltebules & sweat gland) Increases in ECF volume Increases potassium excreation47
  48. 48. Regulation Increase potassium conc. In ECF Decrease sodium conc. In ECF Decreases in ECF volume Adrenocorticotropic hormone48
  49. 49. Glucocorticoids Mainly work on glucose metabolism Secreted from zona faciculata Three of them Cortisol Corticosterone cortisone49
  50. 50. 50Cortisol, the most important glucocorticoid(Glucocorticoid receptors are found in the cells of most vertebrate tissues) It is essential for life (life protecting hormone) Helps the body deal with stressful situations withinminutes Physical: trauma, surgery, exercise Psychological: anxiety, depression, crowding Physiological: fasting, hypoglycemia, fever, infection Regulates or supports a variety of importantcardiovascular, metabolic, immunologic, andhomeostatic functions including water balance
  51. 51. Cont… Mobilization of fatty acid from adiposetissue Increases the utilization of fat as energy Blood ca++ levels decreases Stimulates osteoclastic activity Causes destruction of eosinophils inreticuloendothelial cells Increases the RBCs,platelats,neotrophils51
  52. 52. Cont… Needed for normal functioning of CNS Increases the resistance to stress It has a anti-inflamatory effect Prevents the various reaction in allargiccondition Causes decrease in number of circulatingT lymphocytes52
  53. 53. 53Cortisol, continued Keeps blood glucose levels high enough to supportbrain’s activity Forces other body cells to switch to fats and amino acidsas energy sources Catabolic: break down protein Redirects circulating lymphocytes to lymphoid andperipheral tissues where pathogens usually are In large quantities, depresses immune andinflammatory response Used therapeutically Responsible for some of its side effects
  54. 54. 54Hormonal stimulation of glucocorticoidsHPA axis (hypothalamic/pituitary/adrenal axis) With stress, limbic system is stimulated , andsends impulses to hypothalamus Hypothalamus sends CRH to anterior pituitary(adenohypophysis) Through hypothalamo-hypophysis portalcirculation Pituitary secretes ACTH ACTH goes to adrenal cortex where stimulatesglucocorticoid secretion Sympathetic nervous system can also stimulate it
  55. 55. 55 Steroid-secreting cellshave abundant smoothER As opposed to rough ERin protein-secreting cells Steroids directly diffuseacross plasmamembrane Abundant lipid droplets Raw material fromwhich steroids madeIn general:
  56. 56. Sex hormones Secreted from Zona Reticularis Androgens (male sex hormones) Dehydroepiandrosterone (most activated) Androsterone Testosterone Small quantity of estrogen andprogesterone also secreted by it56
  57. 57. 57Adrenal medulla Part of autonomicnervous system Spherical chromaffincells are modifiedpostganglionicsympathetic neurons Secrete epinephrineand norepinephrine Amine hormones Fight/flight Vesicles store thehormones
  58. 58. Adrenaline & Noradrenaline Two types of receptor Alpha adrenargic hormone Beta adrenargic hormone Increases oxygen consumption Increases BMR Increases blood glucose levels Mobilizes the free fatty acid from adiposetissue Decreases the blood coagulation time 58
  59. 59. Cont… Increases heart rate Increases force of contraction of the heart Increases conductivity of cardiac muscle Causes vasoconstriction Increases systolic blood pressure Increases rate and force of respiration Increases sweating59
  60. 60. Cont… Increases glycogenolysis Causes vasodilatation in skeletal muscle Enhances cortical arousal Increases salivary secretion Increases ACTH secretion Decreases latency of nerve cells Increases renin secrection60
  61. 61. Dopamine Secrated by adrenal medula Also secretion by dopaminargic neuronsof basal ganglia Almost same action as noradrenaline61
  62. 62. 62The PancreasExocrine and endocrine cells Acinar cells (forming most of the pancreas) Head and body Exocrine function Secrete digestive enzymes Islet cells (of Langerhans) Tail of the pancreas Endocrine function
  63. 63. 63Pancreatic isletendocrine cellsAlpha cells: secrete glucagonraises blood sugarmostly in peripheryBeta cells: secrete insulinlowers blood sugarcentral part (are more abundant)Also rare Delta cells:secretesomatostatininhibits glucagon/insuline
  64. 64. Insuline Antidiabetic hormone Increases transport and uptake of glucose Promote peripheral utilization of glucose Promote glycogenesis Inhibits glycogenolysis Increases the permeability for the aminoacids of the cell membrane64
  65. 65. Regulation When blood sugar levels goes up Excess amino acid in blood By secretion of gastric hormones likegastrin,secratin,cholecystokinin Parasympathetic stimulation to pancrease65
  66. 66. Glucagon Increases glycogenolysis in liver Increases blood sugar levels Inhibits secretion of gastric juices Increases secretion of bile66
  67. 67. RegulationIncreases Exercise stress Gastrin Cortisol cholicystokinindecreases Somatostatin Insuline Free fatty acid ketones67
  68. 68. 68The Gonads (testes and ovaries)main source of the steroid sex hormones Testes Interstitial cells secrete androgens Primary androgen is testosterone Maintains secondary sex characteristics Helps promote sperm formation Ovaries Androgens secreted by thecal folliculi Directly converted to estrogens by follicular granulosa cells Granulosa cells also produce progesterone Corpus luteum also secretes estrogen and progesterone
  69. 69. 69The Pineal Gland At the end of a short stalk on the roof ofthe diencephalon Pinealocytes with dense calcium particles Can be seen on x-ray (because of Ca++) Melatonin helps regulate the circadiumrhythm The biological clock Complicated feedback via retina’s visual input
  70. 70. 70Endocrine cells in various organs The heart: atrial natriuretic peptide (ANP) Stimulates kidney to secrete more salt Thereby decreases excess blood volume, highBP and high blood sodium concentration GI tract & derivatives: Diffuseneuroendocrine system (DNES)
  71. 71. 71Endocrine cells in various organs continued The placenta secretes steroid and protein hormones Estrogens, progesterone CRH HCG The kidneys Juxtaglomerular cells secrete renin Renin indirectly signals adrenal cortex to secrete aldosterone Erythropoietin: signals bone marrow to increase RBC production The skin Modified cholesterol with uv exposure becomes Vitamin D precursor Vitamin D necessary for calcium metabolism: signals intestine to absorbCA++
  72. 72. Thank you…72

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