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Section 8.3: Hormones that affect Metabolism

Section 8.3: Hormones that affect Metabolism. Pages 384-387. Recap. Hormones that affect blood sugar Insulin, glucagon, epinephrine, norepinephrine and cortisol Adrenal Glands Glucocorticoids and Mineralocorticoids Diabetes Type I, II and III. 3 Glands that affect Metabolism.

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Section 8.3: Hormones that affect Metabolism

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  1. Section 8.3: Hormones that affect Metabolism Pages 384-387

  2. Recap • Hormones that affect blood sugar • Insulin, glucagon, epinephrine, norepinephrine and cortisol • Adrenal Glands • Glucocorticoids and Mineralocorticoids • Diabetes • Type I, II and III

  3. 3 Glands that affect Metabolism • Thyroid Gland • Parathyroid Glands • Anterior Pituitary Glands

  4. Thyroid Glands

  5. 1. Thyroid Glands • Located at the base of the neck, in front of the trachea • There are two important thyroid hormones • 1. Thyroxine (T4) • 2. Triiodothyronine (T3) • Regulate body metabolism and the growth and differentiation of tissues.

  6. Wow, you have such a fast metabolism.

  7. Thyroxine (T4) Individuals who secrete high levels of T4 oxidize sugars and nutrients at a faster rate • 60%  of oxidized glucose is released as heat • 40%  transferred to ATP • This added energy reserve is usually consumed during activity Result? • Lack of weight gain

  8. Thyroxine (T4) Individuals who secrete low levels of T4 cannot break down sugars and nutrients as easily • Excess blood sugar  converted into liver and muscle glycogen • Once the glycogen stores are filled  converted to fat • Low levels of T4 leads to muscle weakness, cold intolerance and dry skin

  9. The Feedback System • If the metabolic rate decreases  receptors in the hypothalamus are activated • Nerves secrete TRH (thyroid-releasing hormone) • The release of TRH signals pituitary to release TSH (thyroid-stimulating hormone) • TSH is carried by blood to thyroid gland which releases T4 • T4 increases metabolism or increased sugar utilization

  10. The Feedback System nerves blood Figure 3. page 385

  11. Decrease in metabolic rate  TRH  TSH  Thyroxine (T4)  Increased utilization of sugar

  12. Thyroid Disorders • Iodine is an important component of both thyroid hormones (T3 and T4) • When iodine levels begin to decline, the production and secretion of T4 drops • The level of TSH increases and cells of the thyroid continue to develop • The thyroid enlarges  goiter or the swelling of the neck area Figure 4. page 385

  13. 2. Parathyroid Glands • 4 small parathyroid glands exist in the thyroid gland • Usually hormones or nerves regulate endocrine glands  parathyroid is the exception • Respond to chemical changes in surrounding environment

  14. Parathyroid Gland and Calcium • Low calcium levels  release parathyroid hormone (PTH) • PTH causes calcium levels to increase and phosphate levels to decrease • PTH acts on 3 different organs: the kidneys, the intestines and the bones

  15. Parathyroid Gland and Calcium • PTH causes: • The kidneys and gut to retain calcium • Calcium release from the bones • Bone cells break down  calcium is separated from phosphate ions • Calcium is reabsorbed, phosphate is excreted in the urine.

  16. Parathyroid Gland and Calcium • After calcium levels increase, the release of PTH is inhibited to ensure calcium levels are not too high. • If calcium levels increase beyond demand: • The prolonged break down of bone • High levels of calcium could collect in blood vessels and form stone-like structures

  17. PTH Illustration Figure 5. page 386

  18. Low Levels of Vitamin D

  19. Growth Hormone (GH) • Also known as somatotropin • Created by the anterior pituitary • Low levels of GH  dwarfism • High levels of GH  gigantism • Affects most cells in the body, especially cartilage and bone cells • Increases # of cells (hyperplasia) • Increases size of cells (hypertrophy)

  20. Growth Hormone (GH) • Promotes protein synthesis while inhibiting protein degradation • Stimulates ribosomes to follow the genetic instructions for protein synthesis • Promotes the elongation of long bones • Causes a switch in cellular fuels from glucose to fatty acids • As you get older, GH decreases

  21. Summary of Hormones Table 1. page 387

  22. 8.5 Anabolic Steroids Page 388-391

  23. Anabolic steroids: • Designed to build excessive muscle and mimics the traits of the sex hormone  testosterone • Can provide greater lean muscle development and increased strength • Prematurely fuse growth plates in the long bones • Can cause mood swings and feelings of rage

  24. Anabolic steroids don’t: • Provide increased agility or skill level • Enhance the ability of cardiovascular system to deliver oxygen

  25. What are the side effects of prolonged use of anabolic steroids?

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