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Endocrine System

Endocrine System. Ch 16. Hormones. Chemical substances secreted by endocrine (ductless) glands. These chemicals are carried by blood to their respective target cells. Tend to control slow long-term activities in the body. What would be a slow long-term process?. Primary Function of Hormones.

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Endocrine System

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  1. Endocrine System Ch 16

  2. Hormones Chemical substances secreted by endocrine (ductless) glands. These chemicals are carried by blood to their respective target cells. • Tend to control slow long-term activities in the body. • What would be a slow long-term process?

  3. Primary Function of Hormones • Homeostasis • Growth and Development • Reproduction • Energy Metabolism • Behavior

  4. Chemical Composition of Hormones • Lipid soluble: • Steroids • Thyroid • NO • Water soluble: • Proteins/Polypeptides • Amines

  5. hormones endocrine cell receptor protein target cell Mechanism of Action on Target Cells Water soluble response

  6. hormones endocrine cell intracellular receptor target cell Mechanism of Action on Target Cells Lipid soluble response

  7. Steroids

  8. Some Protein/Polypeptide Hormones • Glucagon • Insulin • Oxytocin • ADH • Calcitonin

  9. Amines tyrosine

  10. Amines thyroxine epinephrine

  11. Eicosanoid Fatty acids Prostaglandins • Activate inflammatory response • Stimulate clotting • Induce labor • Inhibit acid in GI tract,  blood flow in kidneys Leukotrines • promote constriction of bronchi (asthma)

  12. stimulates glucose release from liver glucagon from pancreas stimulates inhibits blood glucose high Negative Feedback Loop blood glucose low

  13. Biological Cycles

  14. Control of Hormone Release Capillary (low Ca2+ in blood) PTH Humoral Stimulus

  15. Control of Hormone Release cortex medulla Neural Stimulus

  16. Control of Hormone Release Hormonal Stimulus

  17. Tropic vs Nontropic Hormones Tropic hormones- stimulate the production and secretion of hormones by other endocrine glands; ex. TSH Nontropic hormones- stimulates cellular growth, metabolism, or other functions; ex. thyroxine

  18. Major Endocrine Organs Hypothalamus Pineal gland Pituitary gland Organs containing endocrine cells: Thyroid gland Thymus Parathyroid glands Heart Liver Adrenal glands Stomach Pancreas Kidney Testes Small intestine Kidney Ovaries

  19. pineal gland hypothalamus pituitary gland Endocrine Organs of the Brain

  20. Pineal Gland Produces melatonin (synthesized from seratonin, a derivative of tryptophan) • Secreted directly in CSF to blood • High levels at night make us sleepy; low level during day • Pineal gland is stimulated by darkness and inhibited by light • Function in regulating circadian rhythms (sleep, body temp, appetite)  biological clock

  21. Pituitary Gland hypothalamus anterior pituitary posterior pituitary

  22. Posterior Pituitary

  23. Hormones of the Posterior Pituitary • Antidiuretic Hormone (ADH) • Oxytocin (+ feedback)

  24. Fig. 18.09 ADH

  25. Oxytocin

  26. Anterior Pituitary

  27. Hormones of the Anterior Pituitary • Growth Hormone (GH) • Thyroid Stimulating Hormone (TSH) • Adrenocorticotropic Hormone (ACTH) • Gonadotropins (FSH, LH) • Prolactin (PRL) • Melanocyte-stimulating Hormone (MSH)

  28. Growth Hormone (GH) • Acts on the liver, stimulating it to release several polypeptide hormones. • Stimulates amino acid uptake and protein synthesis in target cells. • Ultimately stimulates cell growth (cell size and number), especially in muscle and bone. • Also stimulates fat breakdown.

  29. Fig. 18.07 GH

  30. strenuous exercise GH Levels sleep awake

  31. Dwarfism hyposecretion of GH Little People Big World Kenadie - worlds smallest girl due to primordial dwarfism

  32. Gigantism hypersecretion of GH Bao Xishun, a 7ft 8.95in herdsman from Inner Mongolia

  33. Acromegaly hypersecretion of GH 7 ft 1 ¼ inches

  34. Thyroid-Stimulating Hormone (TSH) • Acts on the thyroid gland, stimulating it to release T3 & T4 • These thyroid hormones increase glucose catabolism and body heat production. • Negative feedback mechanism involved in regulating levels.

  35. Adrenocorticotropic Hormone (ATCH) • Acts on the adrenal cortex, stimulating it to secrete glucocorticoids (e.g., cortisol). • Glucocorticoids promote the synthesis of glucose from noncarbohydrate sources such as amino acids, and fatty acids • Negative feedback mechanism involved in regulating levels.

  36. Thyroid Gland larynx thyroid trachea

  37. Thyroid Follicles Follicle cells Colloid-filled follicles Parafollicle cells

  38. Thyroid Hormones Thyroid gland selectively uptakes iodine to produce T3 & T4 • Thyroxine (T4) • Triiodothyronine (T3) • Both control metabolic rate and cellular oxidation • Calcitonin (from parafolicular cells)- lowers blood Ca ++ levels and causes Ca++ reabsorption in bone

  39. Fig. 18.12 Thyroid Hormones

  40. Goiter Lack of iodine in diet hyposecretion of T3 & T4

  41. hyposecretion of T3 & T4 Cretinism

  42. Myxedemahyposecretion of T3 & T4 After thyroid treatment myxedema

  43. Exophthalmos-hyperthyroidism

  44. parathyroid glands thyroid esophagus trachea Parathyroid Glands

  45. Parathyroid Hormone (PTH) • PTH release: • stimulates osteoclasts • enhances reabsorption of Ca++ by kidneys • increases absorption of Ca++ by intestinal mucosal cells Hyperparathyroidism- too much Ca++ drawn out of bone; could be due to tumor Hypoparathyroidism- most often follow parathyroid gland trauma or after removal of thyroid--- tetany, muscle twitches, convulsions; if untreatedrespiratory paralysis and death

  46. PTH Effects

  47. Pancreas

  48. Pancreas • Regulates glucose uptake by cells • Controlled via negative feedback: insulin & glucagon • Blood sugar level: 90 mg/mL

  49. Islets of Langerhan

  50. Insulin • Produced by the  cells of the Islets of Langerhan • Catalyze oxidation of glucose for ATP production • Lowers blood glucose levels by promoting transport of glucose into cells. • Stimulates glucose uptake by the liver and muscle cells. • Stimulates glycogen synthesis in the liver and muscle cells (glycogenesis). • Stimulates amino acid uptake and protein synthesis • Stimulate lipogenesis • Decreases glycogenolysis • Decreases gluconeogenesis

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