1. Bone Tissue A. Physiology: functions of bone B. Anatomy: structure of bone C. Histology of bone D. Bone homeostasis 1. Remodeling 1. Remodeling 2. Bone's role in calcium homeostasis 2. Bone's role in calcium homeostasis

2. Physiology: Functions of Bone 1. support 2. protection 3. movement 4. mineral homeostasis 5. blood cell production (hematopoiesis) 6. energy storage

3. Shapes of Bones 1. long 2. short 3. flat 4. irregular

4. Types of Bone 1. compact (dense) 2. spongy (cancellous)

5. Long Bone Anatomy 1. diaphysis 2. epiphysis 3. metaphysis 4. epiphyseal plate (Read bone dvp. pg. 220-227) 5. articular cartilage 6. articular surfaces 7. periosteum a. fibrous a. fibrous b. osteogenic b. osteogenic 8. medullary cavity 9. endosteum

6. Bone Cell Types 1. osteoprogenitor cells 2. osteoblasts -- (osteogenesis) 3. osteocytes– (strain sensors) 4. osteoclasts -- (bone resorption/osteolysis)

7. Bone Matrix 1. ground substance (25%) 2. collagen (25%) 3. mineral salts (50%) -- tricalcium phosphate (hydroxyapatite) -- tricalcium phosphate (hydroxyapatite) -- ossification -- ossification

8. Bone Histology 1. Haversian system (osteon) (osteon) 2. Haversian canal 3. lacuna 4. lamella 5. canaliculus

9. Bone and Calcium Homeostasis 1. remodeling 2. serves to: a. resist mechanical stress a. resist mechanical stress b. remove worn bone b. remove worn bone c. store calcium c. store calcium (1) parathyroid hormone and vitamin D (1) parathyroid hormone and vitamin D (2) calcitonin (2) calcitonin

10. > 10.5 mg/dL < 9.5mg/dL Less kidney reabsorption (more calcium excretion) (osteogenesis) (osteolysis) (Intestinal absorption too)

11. CALCITONIN and BLOOD CALCIUM REGULATION CONTROLLED CONDITION RECEPTOR RETURN TO HOMEOSTASIS EFFECTORS CONTROL CENTER Normocalcemia (blood calcium = 9.5-10.5mg%) A stress or stimulus causes an increase in blood calcium Parafollicular cells of thyroid gland recognize hypercalcemia (blood calcium >10.5 mg% Parafollicular cells secrete calcitonin Reduced osteoclast activity Increased osteoblast activity Increased bone formation results in increased calcium deposition in bone – Return to normocalcemia negative feedback

12. PTH and BLOOD CALCIUM REGULATION CONTROLLED CONDITION RECEPTOR RETURN TO HOMEOSTASIS EFFECTORS CONTROL CENTER Normocalcemia (blood calcium = 9.5-10.5mg%) A stress or stimulus causes a decrease in blood calcium Chief cells of parathythyroid glands recognize hypocalcemia (blood calcium <9.5 mg% Chief cells secrete PTH Increased osteoclast activity Decreased osteoblast activity Increased urine phosphate output Decreased urine calcium output Increased bone breakdown results in increased calcium release to blood – Return to normocalcemia negative feedback end

13. Bone Growth, Stress and Osteoporosis