1. Endocrine System Chapter 18

2. Endocrine System Regulates: – extracellular fluid – metabolism – biological clock – contraction of cardiac & smooth muscle – glandular secretion – some immune functions Controls growth & development Regulates reproductive system … coordinates and controls the activities of the body

3. Endocrine System vs. Nervous System Endocrine System hormones far from site of release cells throughout body seconds - hours - days long duration Nervous System neurotransmitters close to release site muscles, glands, neurons milliseconds brief duration

4. Hormones and Glands Hormones: Chemical substances that are produced in one part of the body and transported by the blood to influence activities in another part of the body

5. Endocrine vs. Exocrine Endocrine hormones into blood pituitary, thyroid, parathyroid. adrenal, pineal secondary function hypothalamus, thymus, pancreas, testes, ovaries, kidneys, stomach, GI, skin, heart, & placenta Exocrine ducts cavity/surface sweat, oil, mucous, digestive glands

6. Principles of Hormone Activity A given hormone affects only target cells Hormone receptors develop as a cell differentiates Different cells may respond in different ways to the same hormone Some hormones are present much of the time, while others appear only sporadically The amount of a circulating hormone is usually governed by negative-feedback control Hormones are usually broken down rapidly

7. Circulating Hormones

8. Cellular Response to Hormones A hormone can increase the rate at which other substances enter or leave the target cell A hormone can stimulate a target cell to synthesize enzymes, proteins, or other substances A hormone can prompt the target cell’s machinery to activate or suppress existing cellular enzymes

9. Hormone Chemistry 2 chemical classes of hormones: 1.Lipid-Soluble - Steroid hormones - Thyroid hormones - Nitric Oxide 2. Water-Soluble - Amine hormones - Peptide and Protein hormones - Eicosanoids

10. Hormone Chemistry

11. Hormone Transport in Blood Water soluble hormones circulate in ‘free’ form in blood Lipid Soluble hormones must attach to transport proteins synthesized by liver –improve transport by making them water-soluble –slow loss of hormone by filtration within kidney –create reserve of hormone

12. Lipid- Soluble Hormones

13. Water-soluble Hormones

14. Second Messengers Some hormones exert their influence by increasing the synthesis of cAMP –ADH, TSH, ACTH, glucagon and epinephrine Some exert their influence by decreasing the level of cAMP –growth hormone inhibiting hormone Other substances can act as 2nd messengers –calcium ions –cGMP Same hormone may use different 2nd messengers in different target cells

15. Amplification of Hormone Effects Single molecule of hormone binds to receptor Activates 100 G-proteins Each activates an adenylate cyclase molecule which then produces 1000 cAMP Each cAMP activates a protein kinase, which may act upon 1000’s of substrate molecules One molecule of epinephrine may result in breakdown of millions of glycogen molecules into glucose molecules

16. Hormonal Interactions Permissive effect –a second hormone, strengthens the effects of the first ex. thyroid strengthens epinephrine’s effect upon lipolysis Synergistic effect –two hormones acting together for greater effect ex. estrogen & LH are both needed for oocyte production Antagonistic effects –two hormones with opposite effects ex. insulin promotes glycogen formation & glucagon stimulates glycogen breakdown

17. Control of Hormone Secretion Regulated by signals from nervous system, chemical changes in the blood or by other hormones Negative feedback control (most common) –decrease/increase in blood level is reversed Positive feedback control –the change produced by the hormone causes more hormone to be released Disorders involve either hyposecretion or hypersecretion of a hormone

18. Endocrine Gland Stimuli 1. Hormonal - where a hormone stimulates the gland to release its hormone 2. Humoral - where the gland monitors the conditions it is going to control 3. Neural - where a nerve impulse stimulates the gland to release its hormone

19. tropic hormone - a hormone that stimulates a gland to release another hormone -tropin a suffix often used on tropic hormones Tropic Hormone

20. Hypothalamus & Pituitary Gland

21. Hormones of the Hypothalamus Oxytocin Antidiuretic hormone (ADH) Releasing hormones Inhibiting hormones

22. Negative feedback regulation of hypothalamus

23. Growth hormone (GH) Thyroid stimulating hormone (TSH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL) Adrenocorticotropin hormone (ACTH) Melanocyte-stimulating hormone (MSH) Anterior Pituitary Hormones

25. Regulation of Growth Hormone

26. Posterior pituitary

28. Regulation of ADH (vasopressin)

29. Oxytocin during Labor Stimulation of uterus by baby Hormone release from posterior pituitary Uterine smooth muscle contracts until birth of baby Baby pushed into cervix, increase hormone release More muscle contraction occurs When baby is born, positive feedback ceases

30. Thyroid Gland T3/T4 Calcitonin

31. Formation of Thyroid Hormone

32. Actions of Thyroid Hormones

33. Control of T3 & T4 Secretion

34. Thyroid Hormones Hyperthyroidism - excessive secretion high basal metabolism (Grave’s disease), high temperature, sweating, weight loss, irritability, high bp Hypothyroidism - deficiency (cretinism) weight gain, lethargy, intolerance to cold, simple goiter

35. Parathyroid Gland

36. Regulation of Calcium Blood Levels

37. Actions of Parathyroid Hormones

38. Adrenal Gland

39. Adrenal Hormones Medulla (catecholamines) epinephrine norepinephrine Cortex mineralocorticoids aldosterone glucocorticoids cortisol corticosterone cortisone androgens dehydroepiandrosterone (DHEA)

40. Cortex –3 zones Medulla Histology of Adrenal Gland

41. Adrenal medulla chromaffin cells - receive innervation from sympathetic nervous system - release epinephrine and norepinephrine in response to stress Produces rapid, drastic effects involving several targets that augment the fight or flight response.

42. Adrenal Cortex Mineralocorticoids aldosterone Glucocorticoids cortisol corticosterone cortisone Androgens dehydroepiandrosterone (DHEA)

43. Mineralocorticoids Aldosterone - increase reabsorption of Na + with Cl - - bicarbonate HCO 3 - and H 2 O follow - promotes excretion of K + and H +

44. Regulation of Aldosterone

45. Glucocorticoids Cortisol - 95% of glucocorticoid activity - protein catabolism - glucose formation - stimulate lipolysis - resistance to stress - anti-inflammatory effects - depression of immune responses

46. Regulation of Glucocorticoids

47. Summary of Adrenal Gland Hormones

48. Pancreas

49. Functions of Pancreas Exocrine function - Acini - - cells clusters that produce digestive enzymes Endocrine function - Islets of Langerhans - clusters of hormone secreting cells

50. Regulation of Glucagon & Insulin Secretion

51. Pancreatic Islet Hormones

52. Pineal Gland

53. Other Hormones

54. Growth Factors

55. Stress Response

56. Pituitary Gland Disorders Pituitary dwarfism - hyposecretion of hGH Giantism - hypersecretion of hGH (childhood) Acromegaly - hypersecretion of hGH (adult)

57. Thyroid Gland Disorders Congenital hypothyroidism - hyposecretion of thyroid hormone Myxedema - hypothyroidism during adult years Grave’s disease - hyperthyroidism - exophthalmos (edema behind eyes) Goiter - enlarged thyroid

58. Adrenal Gland Disorders Cushing’s Syndrome - hypersecretion of cortisol Addison’s Disease - hyposecretion of glucocorticoids and aldosterone

59. Diabetes Mellitus & Hyperinsulinism Type I - insulin-dependent diabetes mellitus (IDDM) Type II - non-insulin-dependent diabetes mellitus (NIDDM)