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22 Cards in this Set
- Front
- Back
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Osteoid
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organic bone matrix secreted by osteoblasts
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Chemical Composition of Bones (Organic)
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Osteogenic cells, osteoblasts, osteocytes, osteoclasts, and osteoid.
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Chemical Composition of Bones (Inorganic)
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Hydroxyapatites (mineral salts). 65% of bone by mass. Mainly calcium phosphate crystals. Responsible for hardness and resistance to compression
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Osteocytes live
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in lacunae
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Osteocytes fuction
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maintain bone calcium levels
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Osteocytes receive nutrients from
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blood vessels via diffusion through canaliculi
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Osteogenesis
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bone tissue formation.
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Bone Formation
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begins in 2nd month of development
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Postnatal Bone Growth begins
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early childhood
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Bone Remodeling and repair
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lifelong
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Bones can form in two ways
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Intramembranous and Endochondral ossification.
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Intramembranous ossification
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Bone development within a membrane. Skull bones develop this way
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Endochondral ossification
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Bone development within a cartilage model. Long bones develop this way
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Hormonal Regulation of Bone Growth
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Growth Hormone stimulates epiphyseal plate, thyroid hormone modulates activity of growth hormone. Testosterone and estrogen at puberty end growth by stopping epiphyseal plate.
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Bone Deposit occurs
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where bone is injures or added strength is needed.
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Bone Resorption
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osteoclasts secrete
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Control of Remodeling
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Hormonal mechanisms that maintain calcium homeostasis in the blood. Mechanical and gravitational forces
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Wolff's Law
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a bone grows or remodels in response to forces or demands placed upon it.
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Location of Hematopoietic Tissue in adults
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Trabecular cavities of the heads of the femur and humerus
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Location of Hematopoietic Tissue in infants
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Medullary cavities and all spaces in spongy bone
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Nearly all bones completely ossified by age
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25
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Bone mass decreases with age beginning in
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4th decade
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