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Chapter 13 Endocrine System

Chapter 13 Endocrine System. Endocrine glands are ductless Exocrine glands have ducts. Endocrine Glands. Paracrine secretions act locally affect only neighboring cells. Endocrine glands release hormones hormones travel through blood to target cells. Autocrine secretions

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Chapter 13 Endocrine System

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  1. Chapter 13Endocrine System • Endocrine glands are ductless • Exocrine glands have ducts

  2. Endocrine Glands • Paracrine secretions • act locally • affect only neighboring cells • Endocrine glands • release hormones • hormones travel through blood to target cells • Autocrine secretions • affect only the secreting cell

  3. Comparison of Nervous System and Endocrine System • Neurons release neurotransmitters into a synapse, affecting postsynaptic cells • Glands release hormones into the bloodstream • Only target cells of hormone responds

  4. Comparison of Nervous System and Endocrine System

  5. Major Endocrine Glands

  6. Chemistry of Hormones • Nonsteroid Hormones • amines • proteins • peptides • glycoproteins • most hormones • Steroid or Steroid-Like Hormones • sex hormones • adrenal cortex hormones

  7. Types of Hormones

  8. Structural Formulas of Hormones

  9. Actions of Steroid Hormones • hormone crosses membranes • hormone combines with receptor in nucleus • synthesis of mRNA activated • mRNA enters cytoplasm to direct synthesis of protein

  10. Actions of Steroid Hormones

  11. Actions of Nonsteroid Hormones • hormone binds to receptor on cell membrane • adenylate cyclase activated • ATP converted to cAMP • cAMP promotes a series of reactions leading to cellular changes

  12. Actions of Nonsteroid Hormones

  13. Prostaglandins • paracrine substances • act locally • very potent in small amounts • regulate cellular responses to hormones • can activate or inhibit adenylate cyclase • controls cAMP production • alters cell’s response to hormones • wide variety of functions

  14. Control of Hormonal Secretions • primarily controlled by negative feedback mechanism

  15. Negative Feedback

  16. Major Endocrine Glands

  17. Pituitary Gland • Two distinct portions • anterior pituitary (adenohypophysis) • posterior pituitary (neurohypophysis)

  18. Pituitary Gland Control • Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones • Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones

  19. Hypothalamic Hormones

  20. Hormones of the Pituitary Gland

  21. Thyroid Gland

  22. Thyroid Gland Hormones

  23. Disorders of the Thyroid Gland

  24. Disorders of the Thyroid Gland • Graves Disease • Hyperthyroidism • Cretinism • Infantile hypothyroidism

  25. Parathyroid Glands

  26. Parathyroid Hormone

  27. Parathyroid Hormone Mechanism by which PTH promotes calcium absorption in the intestine

  28. Disorders of the Parathyroid Glands

  29. Adrenal Glands

  30. Hormones of the Adrenal Medulla

  31. Hormones of the Adrenal Cortex

  32. Hormones of the Adrenal Cortex

  33. Hormones of the Adrenal Cortex

  34. Pancreas

  35. Hormones of the Pancreatic Islets

  36. Insulin and Glucagon Insulin and glucagon function together to stabilize blood glucose concentrations

  37. Other Endocrine Glands • Pineal Gland • secretes melatonin • regulates circadian rhythms • Thymus Gland • secretes thymosins • promotes development of certain lymphocytes • important in role of immunity

  38. Other Endocrine Glands • Reproductive • ovaries produce estrogens and progesterone • testes produce testosterone • placenta produces estrogens, progesterone, and gonadotropins

  39. Stress • Types of Stress • physical stress • psychological stress

  40. Responses to Stress

  41. Life-Span Changes • endocrine glands decrease in size • muscular strength decreases as GH levels decrease • ADH levels increase due to slower break down in liver and kidneys • calcitonin levels decrease; increase risk of osteoporosis • PTH level changes contribute to risk of osteoporosis • insulin resistance may develop • changes in melatonin secretion affect the body clock • thymosin production declines increasing risk of infections

  42. Clinical Application Growth Hormone Ups and Downs • Gigantism - hypersecretion of GH in children • Acromegaly – hypersecretion of GH in adults • Dwarfism – hyposecretion of GH in children Figure shows oversecretion of GH in adulthood as changes occur in the same person at ages (a) nine, (b) sixteen, (c) thirty-three, and (4) fifty-two

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