Dr Stanescu Office Gittings Room 108 email stanescu email arizona edu Office phone 621 2795 Office Hours in Gittings 108 Tue 10 11am and Thurs 1 2pm or by appointment Levels of organization Chemical molecular Cellular Tissue Organ Organ system Organism Already covered Organ systems we will cover this semester skeletal muscular nervous How to study Focus on the information presented in lecture Read the textbook to clarify difficult concepts and use the figures to study anatomy Highlight structures on figures mentioned in class and ignore terms that are not discussed Test your knowledge can you remember what you just read Objectives 1 List and describe the functions of the skeletal system 2 Differentiate between the two divisions of the skeletal system and give examples 3 Describe the classification of bone based on shape giving examples for each type 4 Describe the anatomy of a long bone 5 List and describe the functions of the 4 cell types found in bone 6 Discuss modeling and remodeling of bone Skeletal system components Skeletal system contains bones cartilage ligaments and other connective tissues that attach bones to each other Each bone is an organ contains bone connective tissue blood vessels nerves lymph vessels cartilage connective tissue coverings Skeletal System Functions 1 2 3 4 5 Support Protection Mineral storage Triglyceride storage Red and white blood cell formation hemopoiesis 6 Leverage assistance in movement Divisions of the skeletal system Axial Division Appendicular Division Classification of bones Sutural bone Anatomy of a Long Bone Articular Cartilage Endosteum Epiphysis Metaphysis Spongy Bone Trabecular Compact Bone Diaphysis Periosteum Medullary Cavity Metaphysis Epiphysis Articular Cartilage Endosteum and periosteum are important for bone growth and remodeling Periosteum Connective tissue membrane covering external surface of bone Continuous with tendons connective tissue of joints Attached to bone matrix via perforating fibers Periosteum 2 Layers 1 Outer fibrous 2 Inner osteogenic Endosteum Lining inner surfaces of bone including marrow cavity trabecullae of spongy bone canals of compact bone Contains osteogenic cells important for bone growth and remodeling Endosteum Composition of bone Osteo bone Osteology the study of bone tissue Connective tissue Extracellular Matrix Ground Substance Fibers Contains organic and inorganic components GAG water minerals Collagen Fibers organic Cells Osteogenic cells Osteoblasts Osteocytes Osteoclasts Connective tissue Cells Important in bone remodeling Osteogenic cells Osteoblasts Osteocytes Osteoclasts Osteogenic osteoprogenitor cells Stem cells that are formed from mesenchyme embryonic connective tissue Mitosis Osteogenic cells Differentiation Daughter osteogenic cells Osteoblasts Osteoblasts Cells that build bone bone formation Synthesize organic components of matrix Initiate calcification take calcium from blood and deposit it within matrix by exocytosis Immature cells Osteocytes Mature cells involved in maintenance of bone Osteocyte with its dendritic processes Osteoporosis 3rd ed Marcus Feldman Nelson Rosen Bone form and function 2008 Osteoclasts Break down bone bone resorption Release proteolytic enzymes and acids to degrade collagen and release minerals to blood Derived from myloid stem cells not osteogenic cells Bone modeling remodeling Bone modeling construction is the process by which bone is formed by osteoblasts without prior bone resorption Happens during growth Produces change in bone size and shape Bone remodeling reconstruction occurs when bone is first resorbed by osteoclasts and then formed in the same location by osteoblasts Happens throughout life Goal of modeling remodeling Achieve strength for loading and lightness for mobility How 1 Strategically deposit bone where it is needed 2 Remove bone from where it is not needed to avoid bulk Goal of modeling remodeling During growth To achieve the skeleton s peak strength During adulthood To maintain bone strength by removing damaged bone Bone develops fatigue damage Just like roads and buildings bone develops fatigue damage during repeated loading Bone is able to 1 Detect location and magnitude of damage 2 Remove damage 3 Replace it with new bone 4 Restore bone s material composition micro and macroarchitecture 1 ACTIVATION preosteoclasts are stimulated and differentiate under the influence of cytokines and growth factors into mature active osteoclasts 2 RESORPTION osteoclasts digest mineral matrix old bone 5 QUIESCENCE osteoblasts become resting bone lining cells on the newly formed bone surface Bone Remodeling 3 REVERSAL end of resorption recruitment of osteoblasts 4 FORMATION osteoblasts synthesize new bone matrix www iofbonehealth org