Skeletal system.pptx
- 1. 1 Skeletal System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 2. 2 Introduction • By age 25 the skeleton is completely hardened growth ceases • 206 bones make up the adult skeleton (20% of body mass) • 80 bones of the axial skeleton • 126 bones of the appendicular skeleton
- 3. 3 Functions of skeletal system • Support, Movement & Protection • Gives shape to head, etc. • Supports body’s weight • Protects lungs, etc. • Bones and muscles interact • When limbs or body parts move
- 4. 4 Bone Classification • Bone Classification: • Long Bones • Short Bones • Sesamoid Bones • Flat Bones • Irregular Bones • Wormian Bones (a) (e) (b) (c) (d) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 5. 5 Parts of a Long Bone • Epiphysis • Distal • Proximal • Diaphysis • Metaphysis • Compact bone • Spongy bone • Articular cartilage • Periosteum • Endosteum • Medullary cavity • Trabeculae • Bone marrow • Red marrow and yellow marrow Femur Periosteum Yellow marrow Medullary cavity Space containing red marrow Spongy bone Compact bone Articular cartilage Epiphyseal plates Proximal epiphysis Distal epiphysis Diaphysis Endosteum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 6. 6 Microscopic Structure • Bone cells are called osteocytes • Osteocytes transport nutrients and wastes • The extracellular matrix of bone is largely collagen and i norganic salts • Collagen gives bone resilience • Inorganic salts make bone hard
- 7. 7 Compact Bone • Osteon aka Haversian System • Central canal • Perforating canal aka V olkmann’s canal • Osteocytes • Lamellae • Lacunae • Bone matrix • Canaliculi Nerve Osteon Nerve Nerve Canaliculus Osteocyte Periosteum Endosteum Trabeculae Pores Bone matrix Blood vessels Compact bone Lacuna (space) Blood vessels Perforating canal Central canal containing blood vessels and nerves Central canal Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 8. 8 Spongy Bone • Spongy bone is aka cancellous bone (a) (c) Spongy bone Compact bone (b) Spongy bone Compact bone Remnant of epiphyseal plate Spongy bone Compact bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.
- 9. 9 7.3: Bone Development and Growth • Parts of the skeletal system begin to develop during the f irst few weeks of prenatal development • Bones replace existing connective tissue in one of two w ays: • As intramembranous bones • As endchondral bones
- 10. 10 Intramembranous Bones • Intramembranous Bones • These bones originate within sheetlike layers of connect ive tissues • They are the broad, flat bones • Skull bones (except mandible) • Are known as intramembranous bones
- 11. 11 Endochondral Bones • Endochondral Bones • Bones begin as hyaline cartilage • Form models for future bones • These are most bones of the skeleton • Are known as endochondral bones
- 12. 12 Endochondral Ossification • Hyaline cartilage model • Primary ossification center • Secondary ossification centers • Epiphyseal plate • Osteoblasts vs. osteoclasts (b) (c) (d) (e) (f) (a) Cartilaginous model Calcified cartilage Articular cartilage Developing periosteum Compact bone developing Primary ossification center Medullary cavity Medullary cavity Medullary cavity Secondary ossification center Secondary ossification center Blood vessel Epiphyseal plate Remnant of epiphyseal plate Remnants of epiphyseal plates Epiphyseal plates Compact bone Spongy bone Articular cartilage Spongy bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 13. 13 Animation: Bone Growth in Width Please note that due to differing operati ng systems, some animations will not a ppear until the presentation is viewed in Presentation Mode (Slide Show view). Y ou may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest versio n of the Flash Player, which is available at http://get.adobe.com/flashplayer.
- 14. 14 Growth at the Epiphyseal Plate • First layer of cells • Closest to the end of epip hysis • Resting cells • Anchors epiphyseal plate to epiphysis • Second layer of cells • Many rows of young c ells • Undergoing mitosis 1 2 3 4 (a) (b) Bone tissue of epiphysis Zone of resting cartilage Zone of proliferating cartilage Zone of hypertrophic cartilage Zone of calcified cartilage Ossified bone of diaphysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
- 15. 15 Growth at the Epiphyseal Plate • Third layer of cells • Older cells • Left behind when new cell s appear • Cells enlarging and becom ing calcified • Fourth layer of cells • Thin • Dead cells • Calcified extracellula r matrix 1 2 3 4 (a) (b) Bone tissue of epiphysis Zone of resting cartilage Zone of proliferating cartilage Zone of hypertrophic cartilage Zone of calcified cartilage Ossified bone of diaphysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
- 16. 16 Homeostasis of Bone Tissue • Bone Resorption – action of osteoclasts and parathyroid horm one aka parathormone aka PTH • Bone Deposition – action of osteoblasts and calcitonin • Occurs by direction of the thyroid and parathyroid glands •Figure 7.13 page 205 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Biophoto Associates/Photo Researchers, Inc. Developing medullary cavity Osteoclast
- 17. 17 Factors Affecting Bone Developme nt, Growth and Repair • Deficiency of Vitamin A – retards bone development • Deficiency of Vitamin C – results in fragile bones • Deficiency of Vitamin D – rickets, osteomalacia • Insufficient Growth Hormone – dwarfism • Excessive Growth Hormone – gigantism, acromegaly • Insufficient Thyroid Hormone – delays bone growth • Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates • Physical Stress – stimulates bone growth
- 19. 19 Blood Cell Formation • Blood Cell Formation • Also known as hematopoiesis • Occurs in the red bone marrow
- 20. 20 Inorganic Salt Storage • Inorganic Salt Storage • Calcium • Phosphate • Magnesium • Sodium • Potassium
- 21. 21 7.2 Clinical Application Osteopenia and Osteoporosis: Preventi ng “Fragility Fractures” Page 204