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SKELETAL SYSTEM OVERVIEW. FUNCTIONS. Support Protection Movement-levers Storage-lipids, Ca, P Formation of blood cells-hematopoiesis. STRUCTURE. Two Divisions Axial Appendicular. BONE MARKINGS. Two Categories Processes/projections Depressions/cavities. LONG BONE. Gross anatomy
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FUNCTIONS • Support • Protection • Movement-levers • Storage-lipids, Ca, P • Formation of blood cells-hematopoiesis
STRUCTURE Two Divisions • Axial • Appendicular
BONE MARKINGS Two Categories • Processes/projections • Depressions/cavities
LONG BONE • Gross anatomy • Microscopic anatomy • Bone formation • Bone fractures
COMPOSITION • Lacunae-spaces containing osteocytes • Lamellae-rings of hard, calcified substance • Haversian canals-run longitudinally in bone • Canaliculi-small canals that contain osteocytes
COMPOSITION, cont • Volkmann’s canals-blood vessels, nerves (from periosteum), enter compact bone area which is connected to medullary canals
GROWTH • Epiphyseal plate provides for long growth during childhood • New cartilage formed continuously and old cartilage broken down at same time • Controlled by hormones • Ends at end of adolescence because epiphyseal plate is converted to bone
REMODELING • Old bone destroyed by osteoclasts • New bone made by osteoblasts • Stress of muscle pull and gravity determines what bones formed or were broken down • Bedridden people lose bone mass and subjected to stress
BONE FORMATION and GROWTH • Begins 7th week in utero • 2 kinds: Intramembranous-replacing preexisting connective tissue with bone: hyaline membrane covered with bony matrix by osteoblasts Endochondrial-ossification
ENDOCHONDRIAL • Occurs in most bones • In diaphysis, cartilage degenerates, leaving cavitiesmarrow cavities • Osteoblasts lay down bone • Ossification occurs in epiphysis, where bone replaces cartilage, except plate • Low Ca levels cause change on PTH, causing osteoclasts to destroy bone cells
FRACTURES • Compound • Simple • Compression • Depressed • Impacted • Spiral • Greenstick
TREATMENT of FRACTURES • Reduction-realignment of ends • Closed-Dr., by hand • Open-surgery, pins, wire
JOINTS AND ARTICULATIONS • Position of bony parts is changed • Occurs at the joints • Less movement at closer fittings of bones
CLASSIFICATION • Synarthroses-no movement: skull, sternum, sacrum • Amphiarthroses-little movement: vertebral column, rib cage, axial skeleton • Diarthroses-movement: synovial joint-ball/socket, hinge, pivot, sliding
Disorders of the Joints: Arthritis • Osteoarthritis- chronic, degenerative, affects articular cartilage of the aged (“wear and tear” arthritis)→ exposes bone tissue • Rheumatoid arthritis-chronic, autoimmune, joints swell as synovial fluid accumulates, WBC enter and produce pannus that erodes articular cartilage→ scar tissue which ossifies and bone ends fuse; onset usually 30-40 years of age
ARTHRITIS, con’t • Gout- uric acid accumulates in the blood and depositied in joints, affects single joint; common in males, after age 30 (can lead to immobilization of joint)