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Ch 45: Endocrine System

Ch 45: Endocrine System. Endocrine System. All of the hormone secreting cells Endocrine Glands Secrete hormones Ductless (secrete into bloodstream) Signal Transduction Pathway Most hormones bind to receptor proteins in membrane and cause intracellular response.

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Ch 45: Endocrine System

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  1. Ch 45: Endocrine System

  2. Endocrine System • All of the hormone secreting cells • Endocrine Glands • Secrete hormones • Ductless (secrete into bloodstream) • Signal Transduction Pathway • Most hormones bind to receptor proteins in membrane and cause intracellular response

  3. Chemical Messages (signal-transduction pathways)

  4. Signal Transduction Pathways • Activates a series of molecules within the cell after signal is received • Allow for small amounts of a hormone to have a large effect

  5. Intracellular Hormones • Some hormones will bind to interior receptors and mediate a response • Generally, these act in the nucleus and stimulate a transcription factor (make some enzymes)

  6. Human Endocrine System • Tropic hormones Stimulate other endocrine cells to secrete hormones • Humans have nine endocrine glands

  7. Hypothalamus • Combines the endocrine and nervous systems • Nuerosecretory cells produce hormones • Releasing hormones stimulate the anterior pituitary • Inhibiting hormones prevent the anterior pituitary from secreting hormones

  8. Anterior Pituitary

  9. Posterior Pituitary • Stores and secretes hormones produced by the hypothalamus

  10. Major Hormones

  11. More Hormones

  12. Antidiuretic Hormone (ADH) • Promotes retention of water by the kidneys. • Secretion regulated by water/salt balance • Secreted by post. pituitary after production in hypothalamus

  13. Anterior Pituitary Hormones • Growth hormone • Stimulates growth and metabolism • Gigantism: excessive GH during development • Hypopituitary dwarfism: childhood GH deficiency

  14. Anterior Pituitary Hormones • Prolactin • stimulates milk production and secretion • Gonadotropins • Follicle-stimulating hormone (FSH) • production of sperm and ova • Luteinizing hormone (LH) • stimulates ovaries and testes

  15. Anterior Pituitary Hormones • Thyroid-stimulating hormone (TSH) • stimulates thyroid gland • Melanocyte-stimulating hormone • may play a role in fat metabolism • Endorphins • inhibit pain perception • mimicked by heroin and other opiates

  16. Pineal Gland • Near center of the mammalian brain • Secretes melatonin • Involved in biological rhythms associated with reproduction • Secretion regulated by light/dark cycles

  17. Thyroid Gland • Two lobes locatedon the ventral surfaceof the trachea • T3 (triiodothyronine) and T4 (thyroxine) hormones stimulate and maintain metabolic activity • Secretion of T3 and T4 regulated by TSH hormone secreted by anterior pituitary

  18. Thyroid Gland

  19. Thyroid Gland • Animation of Thyroid Secretion • Animation of Thyroid Regulation • Goiter Animation

  20. Thyroid Gland • Iodine deficiencies lead to goiter (swelling of thyroid gland (why salt is “iodized”) • Hyper- and Hypothyroidism results from too much or too little T3/T4 • Also secretes calcitonin • Lowers blood calcium levels

  21. Parathyroid Glands • four parathyroid glands embedded in the surface of the thyroid gland • parathyroid hormone (PTH) • Raises blood calcium levels • break down bone • reabsorb by kidney • PTH and calcitonin are antagonistic

  22. Regulation of Calcium Levels

  23. Pancreas • Endocrine (into blood) and exocrine (into ducts) • Exocrine: bicarbonate ions and digestive enzymes • Endocrine: insulin and glucagon • Islets of Langerhans

  24. Insulin • Secreted by beta cells • Lowers blood glucose levels • Stimulates all body cells (except brain cells) to take up glucose • Regulated by glucose in blood (negative feedback).

  25. Diabetes • Low or no insulin production • High blood sugar levels • Sugar in urine • Severe diabetes leads to fat usage in cell. respiration and ultimately death (dec. blood pH due to acidic metabolites) • Type I: Autoimmune disorder, present in childhood, treated with insulin injections • Type II: Target cells less responsive over time to insulin. 90% of cases, usually over 40.

  26. Glucagon • secreted by alpha cells • raises blood glucose levels • liver and skeletal muscle breakdown glycogen stores • regulated by glucose in blood (negative feedback)

  27. Blood Sugar Regulation

  28. Adrenal Glands • Adrenal glands • Adjacent to the kidneys • The adrenal cortexis the outer portion • The adrenal medulla is the inner portion • Epinephrine(adrenaline)andnorepinephrine(noradrenaline) • Secretion regulated by the nervous system in response to stress

  29. Response to Stress (Fight or Flight) • Epinephrineandnorepinephrine • Raises blood glucose level and blood fatty acid level • Increase metabolic activities • Increases heart rate and stroke volume anddilates bronchioles • Shunts blood away from skin, digestive organs, and kidneys, and increases blood flow to heart, brain, and skeletal muscle

  30. Testes (testosterone) • Androgen: type of steroids • sperm formation • promote development and maintenance of male sex characteristics • regulated by FSH and LH

  31. Ovaries • Estrogen and progesterone (steroids) • Estrogens • uterine lining growth • female sex characteristics • Regulated by LH and FSH • Progesterone • Uterine lining growth • Reg. by LH and FSH

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