Chapter 18:  The Endocrine System
Endocrine System <ul><li>Regulates long-term processes:  </li></ul><ul><ul><li>growth </li></ul></ul><ul><ul><li>developme...
What are the modes of intercellular communication used by the endocrine and nervous systems?
Direct Communication <ul><li>Exchange of ions and molecules between adjacent cells across gap junctions </li></ul><ul><li>...
Paracrine Communication <ul><li>Chemical signals transfer information from cell to cell within single tissue </li></ul><ul...
Endocrine Communication <ul><li>Endocrine cells   </li></ul><ul><ul><li>release chemicals ( hormones ) into bloodstream </...
<ul><li>Hormones </li></ul><ul><ul><li>Stimulate synthesis of enzymes or structural proteins </li></ul></ul><ul><ul><li>In...
Synaptic Communication <ul><li>Releases neurotransmitter at a synapse that is very close to target cells </li></ul><ul><li...
What are the cellular components of the endocrine system?
<ul><li>Includes all endocrine cells and tissues that produce hormones or paracrine factors </li></ul><ul><li>Endocrine Ce...
Endocrine System Figure 18–1
What are the major structural classes of hormones?
Hormones   <ul><li>Can be divided into 3 groups:  </li></ul><ul><ul><li>amino acid derivatives </li></ul></ul><ul><ul><li>...
Amino Acid Derivatives  <ul><li>Small molecules structurally related to amino acids </li></ul><ul><li>Synthesized from the...
<ul><li>Tyrosine Derivatives  </li></ul><ul><ul><li>Thyroid hormones </li></ul></ul><ul><ul><li>Catacholamines : epinephri...
Peptide Hormones  <ul><li>Chains of amino acids </li></ul><ul><li>Synthesized as prohormones: </li></ul><ul><ul><li>inacti...
Lipid Derivatives <ul><li>Eicosanoids :  </li></ul><ul><ul><li>important paracrine factors </li></ul></ul><ul><ul><li>Leuk...
What are the general mechanisms of  hormonal action?
<ul><li>Receptors are protein molecules to which a particular molecule binds strongly </li></ul><ul><li>Different tissues ...
<ul><li>Hormones bind to receptors in cell membrane </li></ul><ul><ul><li>Cannot have direct effect on activities inside t...
<ul><li>Hormones indirectly: </li></ul><ul><ul><li>alter cellular operations by altering protein composition and activity ...
<ul><li>First messenger : </li></ul><ul><ul><li>leads to  second messenger (cAMP, cGMP, Ca+)   </li></ul></ul><ul><ul><li>...
<ul><li>Down-regulation   </li></ul><ul><ul><li>Presence of a hormone triggers decrease in number of hormone receptors </l...
G Protein <ul><li>Enzyme complex coupled to membrane receptor </li></ul><ul><li>Involved in link between first messenger a...
<ul><li>Activated G protein: </li></ul><ul><ul><li>activates enzyme  adenylate cyclase </li></ul></ul><ul><li>Adenylate cy...
<ul><li>Activated G proteins trigger: </li></ul><ul><ul><li>opening of calcium ion channels in membrane </li></ul></ul><ul...
<ul><li>Activated G protein stimulates phosphodiesterase (PDE) activity </li></ul><ul><li>Inhibits adenylate cyclase activ...
G Proteins and Hormone Activity Figure 18–3
Steroid Hormones <ul><li>Cross cell membrane </li></ul><ul><li>Bind to receptors in cytoplasm or nucleus, activating or in...
Steroid Hormones Figure 18–4a
Steroid Hormones <ul><li>Alter rate of DNA transcription in nucleus: </li></ul><ul><ul><li>change patterns of protein synt...
How are endocrine  organs controlled?
Hypothalamus <ul><li>Integrates activities of nervous and endocrine systems in 3 ways: </li></ul><ul><li>Secretes  regulat...
<ul><li>Acts as an endocrine organ </li></ul><ul><ul><li>manufactures hormones released into the bloodstream via the poste...
Hypothalamus Figure 18–5
Where is the pituitary  gland located, and  what is its relationship  to the hypothalamus?
Pituitary Gland <ul><li>Hangs inferior to hypothalamus: </li></ul><ul><ul><li>connected by  infundibulum </li></ul></ul><u...
Pituitary Gland Figure 18–6
What are the hormones produced by the anterior lobe, and what are the functions of those hormones?
Anterior Pituitary  <ul><li>Thyroid-Stimulating Hormone   (TSH)   </li></ul><ul><ul><li>Also called  thyrotropin </li></ul...
<ul><li>Adrenocorticotropic Hormone   (ACTH)   </li></ul><ul><ul><li>Also called  corticotropin   </li></ul></ul><ul><ul><...
<ul><li>Prolactin   (PRL)   </li></ul><ul><ul><li>Also called  mammotropin </li></ul></ul><ul><ul><li>Stimulates developme...
<ul><li>Growth Hormone (GH)  </li></ul><ul><ul><li>Also called  somatotropin   </li></ul></ul><ul><ul><li>Stimulates cell ...
<ul><li>Melanocyte-Stimulating Hormone (MSH)   </li></ul><ul><ul><li>Also called  melanotropin   </li></ul></ul><ul><ul><l...
<ul><li>Gonadotropins   </li></ul><ul><ul><li>Regulate activities of  gonads  (testes, ovaries) </li></ul></ul><ul><ul><li...
<ul><li>Follicle-Stimulating Hormone (FSH)   </li></ul><ul><ul><li>Also called  follitropin   </li></ul></ul><ul><ul><li>S...
<ul><li>Luteinizing Hormone (LH)  </li></ul><ul><ul><li>Also called  lutropin   </li></ul></ul><ul><ul><li>Causes  ovulati...
What hormones are secreted by the posterior lobe, and  what are their functions?
<ul><li>Antidiuretic Hormone   </li></ul><ul><ul><li>Decreases amount of water lost at kidneys </li></ul></ul><ul><ul><li>...
<ul><li>Oxytocin   </li></ul><ul><ul><li>Stimulates contractile cells in mammary glands </li></ul></ul><ul><ul><li>Stimula...
Summary: The Hormones  of the Pituitary Gland Figure 18–9
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Chapter 18a

  1. 1. Chapter 18: The Endocrine System
  2. 2. Endocrine System <ul><li>Regulates long-term processes: </li></ul><ul><ul><li>growth </li></ul></ul><ul><ul><li>development </li></ul></ul><ul><ul><li>Reproduction </li></ul></ul><ul><li>Uses chemical messengers to relay information and instructions between cells </li></ul>
  3. 3. What are the modes of intercellular communication used by the endocrine and nervous systems?
  4. 4. Direct Communication <ul><li>Exchange of ions and molecules between adjacent cells across gap junctions </li></ul><ul><li>Occurs between 2 cells of same type </li></ul><ul><li>Highly specialized and relatively rare </li></ul>
  5. 5. Paracrine Communication <ul><li>Chemical signals transfer information from cell to cell within single tissue </li></ul><ul><ul><li>paracrine factors – may enter blood stream and function as hormones </li></ul></ul><ul><li>Most common form of intercellular communication </li></ul>
  6. 6. Endocrine Communication <ul><li>Endocrine cells </li></ul><ul><ul><li>release chemicals ( hormones ) into bloodstream </li></ul></ul><ul><ul><li>Alters metabolic activities of many tissues and organs simultaneously </li></ul></ul><ul><li>Target Cells </li></ul><ul><ul><li>possess receptors needed to bind and “read” hormonal messages </li></ul></ul>
  7. 7. <ul><li>Hormones </li></ul><ul><ul><li>Stimulate synthesis of enzymes or structural proteins </li></ul></ul><ul><ul><li>Increase or decrease rate of synthesis </li></ul></ul><ul><ul><li>Turn existing enzyme or membrane channel “on” or “off” </li></ul></ul>
  8. 8. Synaptic Communication <ul><li>Releases neurotransmitter at a synapse that is very close to target cells </li></ul><ul><li>Ideal for crisis management </li></ul>
  9. 9. What are the cellular components of the endocrine system?
  10. 10. <ul><li>Includes all endocrine cells and tissues that produce hormones or paracrine factors </li></ul><ul><li>Endocrine Cells </li></ul><ul><ul><li>Glandular secretory cells that release their secretions into extracellular fluid </li></ul></ul><ul><li>Exocrine Cells </li></ul><ul><ul><li>Secrete their products onto epithelial surfaces </li></ul></ul>
  11. 11. Endocrine System Figure 18–1
  12. 12. What are the major structural classes of hormones?
  13. 13. Hormones <ul><li>Can be divided into 3 groups: </li></ul><ul><ul><li>amino acid derivatives </li></ul></ul><ul><ul><li>peptide hormones </li></ul></ul><ul><ul><li>lipid derivatives </li></ul></ul>
  14. 14. Amino Acid Derivatives <ul><li>Small molecules structurally related to amino acids </li></ul><ul><li>Synthesized from the amino acids tyrosine and tryptophan </li></ul>
  15. 15. <ul><li>Tyrosine Derivatives </li></ul><ul><ul><li>Thyroid hormones </li></ul></ul><ul><ul><li>Catacholamines : epinephrine (E), dopamine norepinephrine (NE) </li></ul></ul><ul><li>Tryptophan Derivative </li></ul><ul><ul><li>Melatonin produced by pineal gland </li></ul></ul>
  16. 16. Peptide Hormones <ul><li>Chains of amino acids </li></ul><ul><li>Synthesized as prohormones: </li></ul><ul><ul><li>inactive molecules converted to active hormones before or after secretion </li></ul></ul><ul><li>ADH, prolactin, oxytocin, growth hormone </li></ul>
  17. 17. Lipid Derivatives <ul><li>Eicosanoids : </li></ul><ul><ul><li>important paracrine factors </li></ul></ul><ul><ul><li>Leukotrienes , Prostaglandins </li></ul></ul><ul><li>Steroid hormones : </li></ul><ul><ul><li>derived from cholesterol </li></ul></ul><ul><ul><li>androgens ( estrogens , and progestins ) corticosteroids, calcitriol </li></ul></ul>
  18. 18. What are the general mechanisms of hormonal action?
  19. 19. <ul><li>Receptors are protein molecules to which a particular molecule binds strongly </li></ul><ul><li>Different tissues have different combinations of receptors </li></ul><ul><ul><li>Presence or absence of specific receptor determines hormonal sensitivity </li></ul></ul>
  20. 20. <ul><li>Hormones bind to receptors in cell membrane </li></ul><ul><ul><li>Cannot have direct effect on activities inside target cell </li></ul></ul>
  21. 21. <ul><li>Hormones indirectly: </li></ul><ul><ul><li>alter cellular operations by altering protein composition and activity </li></ul></ul><ul><ul><li>stimulate protein synthesis </li></ul></ul><ul><ul><li>activate proteins </li></ul></ul><ul><ul><li>modulate current levels of protein synthesis </li></ul></ul>
  22. 22. <ul><li>First messenger : </li></ul><ul><ul><li>leads to second messenger (cAMP, cGMP, Ca+) </li></ul></ul><ul><ul><li>A single hormone promotes release of more than 1 type of second messenger </li></ul></ul>
  23. 23. <ul><li>Down-regulation </li></ul><ul><ul><li>Presence of a hormone triggers decrease in number of hormone receptors </li></ul></ul><ul><li>Up-regulation </li></ul><ul><ul><li>Absence of a hormone triggers increase in number of hormone receptors </li></ul></ul>
  24. 24. G Protein <ul><li>Enzyme complex coupled to membrane receptor </li></ul><ul><li>Involved in link between first messenger and second messenger </li></ul><ul><li>Binds GTP </li></ul><ul><li>Activated when hormone binds to receptor at membrane surface </li></ul>
  25. 25. <ul><li>Activated G protein: </li></ul><ul><ul><li>activates enzyme adenylate cyclase </li></ul></ul><ul><li>Adenylate cyclase: </li></ul><ul><ul><li>converts ATP to cyclic-AMP </li></ul></ul><ul><li>Cyclic-AMP (second messenger): </li></ul><ul><ul><li>activates kinase </li></ul></ul><ul><li>Activated kinases affect target cell: </li></ul><ul><ul><li>depends on nature of proteins affected </li></ul></ul>
  26. 26. <ul><li>Activated G proteins trigger: </li></ul><ul><ul><li>opening of calcium ion channels in membrane </li></ul></ul><ul><ul><li>release of calcium ions from intracellular stores </li></ul></ul>
  27. 27. <ul><li>Activated G protein stimulates phosphodiesterase (PDE) activity </li></ul><ul><li>Inhibits adenylate cyclase activity </li></ul><ul><li>Levels of cAMP decline </li></ul><ul><li>cAMP breakdown accelerates; cAMP synthesis is prevented </li></ul>
  28. 28. G Proteins and Hormone Activity Figure 18–3
  29. 29. Steroid Hormones <ul><li>Cross cell membrane </li></ul><ul><li>Bind to receptors in cytoplasm or nucleus, activating or inactivating specific genes </li></ul>
  30. 30. Steroid Hormones Figure 18–4a
  31. 31. Steroid Hormones <ul><li>Alter rate of DNA transcription in nucleus: </li></ul><ul><ul><li>change patterns of protein synthesis </li></ul></ul><ul><li>Directly affect metabolic activity and structure of target cell </li></ul>
  32. 32. How are endocrine organs controlled?
  33. 33. Hypothalamus <ul><li>Integrates activities of nervous and endocrine systems in 3 ways: </li></ul><ul><li>Secretes regulatory hormones : </li></ul><ul><ul><li>special hormones control endocrine cells in pituitary gland </li></ul></ul>
  34. 34. <ul><li>Acts as an endocrine organ </li></ul><ul><ul><li>manufactures hormones released into the bloodstream via the posterior pituitary </li></ul></ul><ul><li>Contains autonomic centers: </li></ul><ul><ul><li>exert direct neural control over endocrine cells of adrenal medullae </li></ul></ul>
  35. 35. Hypothalamus Figure 18–5
  36. 36. Where is the pituitary gland located, and what is its relationship to the hypothalamus?
  37. 37. Pituitary Gland <ul><li>Hangs inferior to hypothalamus: </li></ul><ul><ul><li>connected by infundibulum </li></ul></ul><ul><li>Releases 9 important peptide hormones </li></ul><ul><li>Hormones bind to membrane receptors: </li></ul><ul><ul><li>use cAMP as second messenger </li></ul></ul>
  38. 38. Pituitary Gland Figure 18–6
  39. 39. What are the hormones produced by the anterior lobe, and what are the functions of those hormones?
  40. 40. Anterior Pituitary <ul><li>Thyroid-Stimulating Hormone (TSH) </li></ul><ul><ul><li>Also called thyrotropin </li></ul></ul><ul><ul><li>Triggers release of thyroid hormones </li></ul></ul><ul><ul><li>hypothalamic regulatory hormone </li></ul></ul><ul><ul><ul><li>Thyrotropin Releasing Hormone (TRH) </li></ul></ul></ul>
  41. 41. <ul><li>Adrenocorticotropic Hormone (ACTH) </li></ul><ul><ul><li>Also called corticotropin </li></ul></ul><ul><ul><li>Stimulates release of steroid hormones by adrenal cortex </li></ul></ul><ul><ul><li>hypothalamic regulatory hormone </li></ul></ul><ul><ul><ul><li>Corticotropin Releasing Hormone (CRH) </li></ul></ul></ul>
  42. 42. <ul><li>Prolactin (PRL) </li></ul><ul><ul><li>Also called mammotropin </li></ul></ul><ul><ul><li>Stimulates development of mammary glands and milk production </li></ul></ul><ul><ul><li>hypothalamic regulatory hormone </li></ul></ul><ul><ul><ul><li>prolactin-inhibiting hormone (PIH) </li></ul></ul></ul>
  43. 43. <ul><li>Growth Hormone (GH) </li></ul><ul><ul><li>Also called somatotropin </li></ul></ul><ul><ul><li>Stimulates cell growth and replication </li></ul></ul><ul><ul><li>hypothalamic regulation </li></ul></ul><ul><ul><ul><li>growth hormone–releasing hormone (GH–RH) </li></ul></ul></ul><ul><ul><ul><li>growth hormone–inhibiting hormone (GH–IH) </li></ul></ul></ul>
  44. 44. <ul><li>Melanocyte-Stimulating Hormone (MSH) </li></ul><ul><ul><li>Also called melanotropin </li></ul></ul><ul><ul><li>Stimulates melanocytes to produce melanin </li></ul></ul><ul><ul><li>Inhibited by dopamine </li></ul></ul>
  45. 45. <ul><li>Gonadotropins </li></ul><ul><ul><li>Regulate activities of gonads (testes, ovaries) </li></ul></ul><ul><ul><li>hypothalamic regulation </li></ul></ul><ul><ul><ul><li>gonadotropin-releasing hormone (GnRH) </li></ul></ul></ul><ul><ul><li>GnRH production inhibited by estrogens, progestins, and androgens </li></ul></ul>
  46. 46. <ul><li>Follicle-Stimulating Hormone (FSH) </li></ul><ul><ul><li>Also called follitropin </li></ul></ul><ul><ul><li>Stimulates follicle development and estrogen secretion in females </li></ul></ul><ul><ul><li>Stimulates sustentacular cells in males </li></ul></ul><ul><ul><ul><li>promotes physical maturation of sperm </li></ul></ul></ul><ul><ul><li>Production inhibited by inhibin released by testes and ovaries </li></ul></ul>
  47. 47. <ul><li>Luteinizing Hormone (LH) </li></ul><ul><ul><li>Also called lutropin </li></ul></ul><ul><ul><li>Causes ovulation and progestin production in females </li></ul></ul><ul><ul><li>Causes androgen production in males </li></ul></ul>
  48. 48. What hormones are secreted by the posterior lobe, and what are their functions?
  49. 49. <ul><li>Antidiuretic Hormone </li></ul><ul><ul><li>Decreases amount of water lost at kidneys </li></ul></ul><ul><ul><li>Elevates blood pressure </li></ul></ul><ul><ul><li>Release inhibited by alcohol </li></ul></ul>
  50. 50. <ul><li>Oxytocin </li></ul><ul><ul><li>Stimulates contractile cells in mammary glands </li></ul></ul><ul><ul><li>Stimulates smooth muscles in uterus </li></ul></ul>
  51. 51. Summary: The Hormones of the Pituitary Gland Figure 18–9
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