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BONES Facts Recycle 5-7% each week Distal end of femur replaced every 5 months Vary greatly in size femur & stapes in ear Functions Support Protect Movement Mineral Storage Ca, Mg, P, Na, S Energy Storage lipid in marrow Hematopoeisis blood cell production Axial vs Appendicular Classifications Long Short Flat Irregular Anatomical Structure Long bones Epiphysis end of long bones Diaphysis body/ shaft Medullary cavity hollow part Red marrow- blood cell production Yellow marrow- fat Metaphysic where epiphysis & diaphysis meet Epiphyseal plate growth plate Cartilage line between epi & dia Turns to epiphyseal line after done growing Endostium CT lining in cavity Periostium CT lining outside of bone Sharpy’s fibers anchor periostium to bone Nutrient foramen hole for vessel to enter bone Nutrient artery vessel that goes into bone Regions Compact (dense) bone Osteon circular collection of lamella Spongy (cancellous) Trabeculae solid structure of spongy bone Osteon basic repeating unit of compact bone Central canal Haversian canal Has artery in middle of osteon Volkmann’s canal connects osteons Lamellae hard matrix between cells Bone Homeostasis Remodeling bones constantly break down & build up Osteoclast break down bone Osteoblast build up bone Osteocyte mature bone cell Bone Formation Ossification Intramembranous fibrous membrane turn to bone Flat bones in skull Intracartilaginous endochondrial Cartilage turns to bone Starts in middle of bone Then ends start to grow Come together at epiphyseal plate/ line Bone Growth Length occurs at epiphyseal plate Cartilage cells produce Cartilage removed by osteoclast & replaced by osteoblast After puberty chondrocytes (cartilage cells) divide less often Thickness osteoprogenitor cells create new osteoblasts on edge of bone Calcium Homeostasis Parathyroid Hormone Parathyroid gland Increase osteoclast activity Increase blood Ca levels Decrease bone density Both work by negative feedback systems Fracture & Repair Fracture hematoma Cells migrate to fracture zone Fibrocartilaginous callus forms Bony callus forms Bone remodeling Types of fractures Partial vs complete Closed skin not broken Open skin broken Calcitonin thyroid gland decrease osteoclast activity decrease blood Ca levels increase bone density Comminuted bone fragments Greenstick bent like green twig (partial break) Spiral corkscrew break Bone & Aging Demineralization loss of minerals Females start at 30 years Loss of estrogen Males start at 60 years Protein synthesis less collagen = more brittle bones Rickets Vitamin D deficiency Soft bones Osteoporosis Decreased bone mass Low estrogen = low osteoblast activity Increased PTH Cartilage chondrocytes Hyaline ribs, nose, hip, shoulder Fibrous intervertebral disk & pubic symphsys Elastic ear
