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Chapter 47

Chapter 47. Endocrine Regulation. The endocrine system Endocrine glands, cells, and tissues that secrete hormones Hormones are an important type of chemical signal by which cells communicate Secreted into the interstitial fluid and typically transported by the blood

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Chapter 47

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  1. Chapter 47 Endocrine Regulation

  2. The endocrine system • Endocrine glands, cells, and tissues that secrete hormones • Hormones are an important type of chemical signal by which cells communicate • Secreted into the interstitial fluid and typically transported by the blood • Bind with receptors or in specific target cells

  3. Some types of endocrine signaling

  4. Four main chemical groups • Fatty acid derivatives • Prostaglandins and the juvenile hormone of insects • Steroids • Secreted by the adrenal cortex, ovary, and testis, as well as the molting hormone of insects

  5. Four main chemical groups, cont. • Amino acid derivatives • Thyroid hormones and epinephrine • Peptides or proteins • ADH and glucagon are peptide hormones • Insulin is a small protein

  6. Majorchemical groups of hormones

  7. Hormone secretion • Typically regulated by negative feedback mechanisms • Hormone is released in response to some change in a steady state • Triggers a response that counteracts the changed condition • This process restores homeostasis

  8. Regulation by negative feedback

  9. Steroid and thyroid hormones • Hydrophic molecules • Pass through the plasma membrane • Combine with receptors within the target cell • The hormone-receptor complex may activate or repress transcription of messenger RNA coding for specific proteins

  10. Mechanism of action of steroid hormones

  11. Peptide hormones are hydrophillic and do not enter target cells • Combine with receptors on the plasma membrane of target cells • Many hormones bind to G protein-linked receptors • Act via signal transduction

  12. Overview of peptide hormone action

  13. Mechanism of action of hormonesthat use G protein-linked receptors and second messengers

  14. Most peptide hormones are first messengers • Carry out their actions by way of second messengers • Cyclic AMP (cAMP) • Calcium ions

  15. Phospholipid products as second messengers

  16. Inositol trisphosphat (IP3) and diacylglycerol (DAG) • Second messengers that • Increase calcium concentration • Activate enzymes

  17. Receptor tyrosine kinases • Enzyme-lined receptors • Bind growth factors, including insulin and nerve growth factors

  18. Signal amplification • Occurs as each hormone-receptor complex stimulates the production of second messenger molecules • Second messengers activate protein kinase molecules that activate protein molecules

  19. Four functions of hormones in invertebrates • Neurohormones secreted by neurons rather than endocrine glands

  20. Four functions of hormones in invertebrates, cont. • Help regulate • Metabolism • Growth and development • Regeneration • Molting • Metamorphosis • Reproduction and behavior

  21. Regulation of growth and molting in insects

  22. Human endocrine glands

  23. Some endocrine glands and their hormones

  24. Consequences of endocrine malfunction

  25. Nervous and endocrine regulation • Integrated in the hypothalamus, which regulates the pituitary gland

  26. Oxytocin and ADH • Produced by the hypothalamus • Released by the posterior lobe of the pituitary

  27. Hypothalamus • Secretes • Releasing hormones • Inhibiting hormones • These regulate the hormone output of the anterior lobe of the pituitary

  28. Anterior lobe of the pituitary • Secretes the growth hormone, prolactin • Several tropic hormones that stimulate other endocrine glands

  29. The hypothalamus regulates the anterior lobe of the pituitary gland

  30. Growth hormone (GH) • Anabolic hormone that stimulates body growth • Stimulates the liver to produce insulin-like growth factors (IGFs), which promote skeletal and tissue growth

  31. Thyroid gland • Secretes • Thyroxine • Triiodothyronine • Stimulate the rate of metabolism

  32. Regulation of thyroid secretion • Depends mainly on a negative feedback system • Anterior pituitary gland • Thyroid gland

  33. Thyroid hyposecretion • Childhood cretinism • Adult myxedema • Thyroid hypersecretion • Most common cause is Grave’s disease • Goiter associated with both hyposecretion and hypersecretion

  34. Regulation of thyroid secretion by negative feedback

  35. Parathyroid glands • Secrete PTH • Regulates calcium level in the blood • Stimulates calcium release from bones • Calcitonin, secreted by the thyroid, acts antagonistically to PTH

  36. Regulation of calcium homeostasis by PTH and calcitonin

  37. Islets of Langerhans • Secrete insulin • Stimulates cells to take up glucose and so lowers blood glucose • Secrete glucagon • Raises blood glucose concentration • Diabetes mellitus • Results in decreased use of glucose

  38. Islets of Langerhans

  39. Adrenal glands • Secrete hormones that help the body cope with stress • Adrenal medulla secretes • Epinephrine • Norepinephrine • Adrenal cortex secretes • Sex hormones

  40. Adrenal gland

  41. Response to stress

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