Skeletal System FUNCTIONS OF SKELETON Support of trunk and skull Protection of underling organs Movement - attachment for muscles Mineral homeostasis Hemopoiesis - all blood cells Energy Storage CLASSIFICATION OF BONES Long bones Short bones Flat bones Irregular bones Seasmoid bone develop within a tendon Wormian bones tiny bones in between major skull bones Click screen to add animated notes

PARTS OF A LONG BONE Periosteum outer fibrous protective covering Diaphysis - shaft Mainly compact bone Medullary cavity contains yellow marrow lined with endosteum Periosteum outer fibrous protective covering osteogenic layer attached to bone by Sharpey’s fibers serves as an insertion for ligaments and tendons. Click screen to add animated notes Epiphyses -proximal and distal ends covered with articular cartilage mainly spongy (cancellous) bone trabeculae (small needle like projections) red marrow-hematopoietic contains the epiphyseal (growth) plate

Bone Features Joint Structures Fossa Condyle Epicondyle Head For Muscle attachment Trochanter Tuberosity Process Crest Linea Fovea Tubercle Click screen to add animated notes Passageways for vessels, etc. Foramen Fissure Meatus Space within a Bone - Sinus

Compact and Spongy Bone Click screen to add animated notes

MICROSCOPIC STRUCTURE Spongy bone microscopic structure trabeculae spaces filled with red marrow Compact bone Microscopic structure Made of osteons (Haversian System) concentric lamellae (calcified matrix) central canal containing blood vessels and nerves osteocytes in lacunae Canals carrying nutrients to osteocytes Canaliculi -connecting lacunae Volkmans's -connecting osteons (right angles to central canals) Click screen to add animated notes Chemical structure Organic components (35%) Cells Osteoblasts Osteocytes Osteoclasts Osteoid - mainly collagen for tensile strength Inorganic component - 65% (hydroxyapatite- calcium phosphate) gives hardness to bone.

Embryonic Bone Development (Osteogeneis) fontanel Intramembranous (ossification of fibrous CT) - flat bones Osteoprogenitor cell differentiate into osteoblasts Ossification's centers develop in the center of the bone Periosteum develops and blood vessels invade developing centers Endochondral (Ossification of hyaline cartilage) - long bones Calcified cartilage Ossification centers (primary & secondary) Invasion of blood vessels Formation of the medullary cavity Click screen to add animated notes Epiphyseal plate

BONE GROWTH Physical Stress – stimulates bone growth Width (appositional growth)- occurs in nutrient periosteum Bone remoldeing - resorption and depositing Length (longitudinal growth) - Epiphyseal plate Proliferation zone Zone of hypertrophy Calcification of dead cells Bone trabeculae --> Compact bone Factors effecting bone growth/homeostasis Nutrition - Ca, P, Mg, vitamins, A, C and D. Hormones in general – Growth,Thyroid,Sex Click screen to add animated notes Hormones that maintain blood calcium Parathyroid - released when? Vitamin D for Ca+ absorption Resorption of Ca+ by kidneys Stimulation of osteoclasts Calcitonin - released when? stimulates osteoblast activity

Bone Fractures Fracture Repair Osteoporosis Animation & another source Click screen to add animated notes