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Bones & Skeletal Tissue. Ch 6. Function of the Skeletal System. Support Protection Movement Mineral storage Blood cell formation (hemopoiesis) Triglyceride storage. Bones & Cartilage. Anatomy of a Long Bone. spongy bone. Proximal epiphysis. compact bone. Endosteum. diaphysis.
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Function of the Skeletal System • Support • Protection • Movement • Mineral storage • Blood cell formation (hemopoiesis) • Triglyceride storage
Anatomy of a Long Bone spongy bone Proximal epiphysis compact bone Endosteum diaphysis epiphyseal line yellow marrow Sharpey’s fibers Distal epiphysis periosteum hyaline cartilage
Haversian system spongy bone central canal osteocyte compact bone periosteum
osteocytes in lacunae canaliculi in matrix central canal Haversian System in Compact Bone
Fetal Skeleton 275 bones12 weeks (6-9 inches long)
Fetus: 1st 2 months Endochondral Ossification 2o ossification center bone cartilage calcified cartilage Just before birth epiphyseal line epiphyseal plate Childhood Adult
Hormonal Regulation of Bone Growth • GH from anterior pituitary, which is regulated by T3 and T4 of the thyroid • During puberty- sex hormones: estrogen and testosterone • Hyposecretion of GH- dwarfism • Hypersecretion of GH- gigantism
Bone Homeostasis: Remodel & Repair • Parathyroid hormone- stimulates osteoclasts • Calcitonin- inhibits osteoclasts Maintains homeostasis
Bone Homeostasis: Remodel & Repair
Bone cells that aid in remodeling Builds new bone Osteoblast Mature bone cell Osteocyte Osteoclast Eats bone
Repair of Fractures hematoma callus bony callus bone remodeling
Common Types of Fractures Usually treated by realignment • Simple- closed fracture (8-12 wks to heal) bone breaks cleanly; no penetration • Compound- bone penetrates through skin • Comminuted- bone fragments into many pieces; aged or brittle bones • Compression- bone is crushed • Depressed- broken bone portion is depressed inward • Impacted- broken bone ends are forced into each other • Spiral- excessive twisting of bone • Greenstick- bone breaks incompletely
Common Types of Fractures Oblique Comminuted Spiral Compound
Bone Repair • Electrical stimulation of the fracture site: • Increases speed and completeness of healing • The e- stimulation inhibits PTH and slow osteoclasts down from reabsorbing bone • 2. Ultrasound treatment: • Daily treatments reduce healing time of broken bones by 25-35% • 3. Free vascular fibular graft technique: • Transplant fibula in arm • Gives good blood supply not available in other treatments • 4. Bone substitutes: • Crushed bone from cadaver- but risk of HIV and hepatitis • Sea bone- coral • Artificial bone- ceramic
Diseases of the Skeletal System • Osteoporosis- bone reabsorption outpaces bone deposit; bones become lighter and fracture easier • Factors: • age, gender (more in women) • estrogen and testosterone decrease • insufficient exercise (or too much) • diet poor in Ca++ and protein • abnormal vitamin D receptors • smoking
29 40 84 92 Osteoporosis
Diseases of the Skeletal System • Rickets- vitamin D deficiency • Osteomalacia- soft bones, inadequate mineralization in bones, lack of vitamin D • Pagets Disease- spotty weakening in the bones, excessive and abnormal bone remodeling • Rheumatoid arthritis- autoimmune reaction
INQUIRY • What does the secondary site of ossification produce? • What is an epiphyseal line? • Provide an example of a flat bone? • How does PTH effect bone development? • How many bones in the adult skeleton? • What does an osteoblast do and where are they primarily found? http://www.youtube.com/watch?v=DSHoonPWwXQ