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1. Infancy & Childhood : G rowth Hormone: Thyroid Hormone :

Chapter 6 … III. Bone Formation and Development … E. Hormonal Regulation of Bone Growth In Children. 1. Infancy & Childhood : G rowth Hormone: Thyroid Hormone : 2. During puberty: Test. and Estrogens :  adolescent growth spurts induces epiphyseal closure– end growth.

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1. Infancy & Childhood : G rowth Hormone: Thyroid Hormone :

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  1. Chapter 6 …III. Bone Formation and Development …E. Hormonal Regulation of Bone Growth In Children 1. Infancy & Childhood: • Growth Hormone: • Thyroid Hormone: 2. During puberty: Test. and Estrogens: •  adolescent growth spurts • induces epiphyseal closure– end growth

  2. F. Bone Remodeling in Adults - When: - Amount: 5-10% annually in an adult • Function: 1) 2) 3) 1. Importance of Calcium • Nerve • Muscle • Blood Clotting • Cell division

  3. Control of Remodeling …2. Hormones That Influence Osteoclasts Controls - Affected by Ca+ blood levels - Negative Feedback Loops • Parathryroid Hormone– determines when to remodel • Parathyroid Gland cells: If low blood Ca+2, PTH increases  Activates Osteoclasts  Ca+2 blood levels increase b) Calcitonin • Much less involved • Functions in oposition to PTH 3. Where to Remodel: determined by mechanical stresses • Gravity • Exercise 4. Other Factors: UV light & Vitamine D

  4. IV. Bone Repair- Fractures • Classification by complexity, location, and other features: • Closed (Simple) vs. Open (Compound): • Completeness of break:

  5. F. Types of Fractures … Table 6.2.1

  6. Table 6.2.2

  7. Table 6.2.3

  8. G. Bone Repair • Treating Fractures • Reduction = realignment • Immobilization The Body’s Process of Repair 1. Fracture Hematoma (immediate – 1st day or 2) • Swollen • Painful • Inflamation Figure 6.13.1

  9. G. Bone Repair … 2. Fibrocartilage Callus (few days – 1-2 weeks) • New capillaries grow • Phagocytes clean up the dead • Fibroblasts & osteogenic cells come in and collagen fibers are produced to span the break • Chondrocytes develop and produce fibrocartilage • Externally bulging cartilage matrix forms Figure 6.13.2

  10. Repair … 3. Bony callus of Spongy Bone - few weeks – 2 to 3 months • Osteoblastsbegin forming spongy bone that invades cartilage Figure 6.13.3

  11. Repair … 4. Bone remodeling - (up to several months after bony callus) • Excess material on outside and inside removed • Resembles original with slight bulge Figure 6.13.4

  12. Homeostatic ImbalancesSTUDENTS DO • Rickets • Osteoporosis

  13. END

  14. Participating . . . 2a. List 2 reasons why bones are remodeled in adults? Regulate blood calcium, compensate for stress, also to repair fractures, renew matrix 2b. Why do exercisers have denser and stronger bones? • Bones develop over longer time periods in exercisers • Bone remodeling adds bone tissue to compensate for the stress of exercise • Exercisers need more calcium for their muscles a b

  15. Participating… 4. Which of the following might help delay or even prevent the effects of osteoporosis? Why? • Being sure to include plenty of calcium in the diet. • Getting regular exercise. • Resting bones as often as possible.

  16. Hematoma Externalcallus Bonycallus ofspongybone Internalcallus(fibroustissue andcartilage) Newbloodvessels Healedfracture Spongybonetrabecula Bone remodeling Hematomaformation Fibrocartilagecallus formation Bony callusformation Participate: 3. List 4 steps of bone repair. 1. Hematoma (blood-filled swelling) is formed 2. Break splinted by fibrocartilage to form a callus 3. Fibrocartilage callus replaced by a bony callus 4. Bony callus is remodeled to form a permanent patch

  17. Hormonal Control of Blood Ca – raising Ca concentration Imbalance Calcium homeostasis of blood: 9–11 mg/100 ml Falling blood Ca2+ levels Imbalance Figure 6.11

  18. Hormonal Control of Blood Ca – raising Ca concentration Imbalance Calcium homeostasis of blood: 9–11 mg/100 ml Falling blood Ca2+ levels Imbalance Thyroid gland Parathyroid glands Parathyroid glands release parathyroid hormone (PTH) Figure 6.11

  19. Hormonal Control of Blood Ca – raising Ca concentration Imbalance Calcium homeostasis of blood: 9–11 mg/100 ml Falling blood Ca2+ levels Imbalance Thyroid gland Parathyroid glands Parathyroid glands release parathyroid hormone (PTH) PTH Figure 6.11

  20. Hormonal Control of Blood Ca – raising Ca concentration Imbalance Calcium homeostasis of blood: 9–11 mg/100 ml Falling blood Ca2+ levels Imbalance Thyroid gland Osteoclasts degrade bone matrix and release Ca2+ into blood Parathyroid glands Parathyroid glands release parathyroid hormone (PTH) PTH Figure 6.11

  21. Hormonal Control of Blood Ca – raising Ca concentration Calcium homeostasis of blood: 9–11 mg/100 ml Falling blood Ca2+ levels Thyroid gland Osteoclasts degrade bone matrix and release Ca2+ into blood Parathyroid glands Parathyroid glands release parathyroid hormone (PTH) PTH Figure 6.11

  22. Surgical Neck- most common break point Control of Remodeling …Response to Mechanical Stress • Determine WHERE remodeling occurs • Wolff’s law – bones remodel in response to stresses

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