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Bone (osseous tissue)
connective tissue with the matrix hardened by calcium phosphate and other minerals
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Osteoblasts
bone forming cells
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Osteocytes
formed osteoblasts, trapped in matrix
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osteoclasts
break down, or dissolve bone
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The Matrix
by dry weight, about one-third organic and two-thirds inorganic matter
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Rickets
soft bones due to deficiency in calcium salts happen due to Vitamin D deficiency
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Red Marrow (Hemopoietic tissue)
produces blood cels in is make up of many different tissues, and makes up an organ to itself
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Yellow Marrow
Found in adults, red marrow turns into fatty yellow, it no longer produces blood
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Ossification (Osteogenesis)
the formation of bone, continues throughout life with growth and remodeling
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Intramenbranous Ossification Stages
- produce the flat bones of skull+clavicle,
- 1. condensation of mesenchyme into soft sheet permeated with blood capillaries
- 2. Deposition of osteoid tissue by osteoblasts on mesenchymal surface; entrapment of osteocytes; formation of periosteum
- 3. Honeycomb of bony trabeculae formed by continued mineral deposition, creation of spongy bone
- 4. Surface bone filled by bone deposition converting spongy bone into compact; Persistence of spongy bone in the middle layer.
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Endochondral Ossification Stages
- Process in which bone develops from preexisting cartilage
- 1. Formation of primary ossification center, bony collar and periosteum
- 2.Vascular invasion, formation of primary marrow cavity and secondary marrow cavity in 1 epiphysis appears
- 3. Child bone epiphyseal plate open
- 4 Adult bone single marrow cavity, epiphysis plate closed
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Bone elongation
- epiphyseal plate a region of transition from cartilage to bone, a growth zone
- cartilage is being replaced by bone
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Metaphysis
is the zone of transition facing the marrow cavity
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Zone of reserve cartilage
typical hyaline cartilage farthest from marrow cavity, shows no sign of transforming into bone
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Zone of Proliferation
chondrocytes multiply forming columns of flat lacunae
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Zone of hypertrophy
chondrocyte enlargement, matrix between lacunae become very thin
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Zone of calcification
mineral deposited in the matrix between columns of lacunae, temporary support for cartilage
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Zone of bone deposition
chondrocytes die, horizontal columns fill with osteoblasts and blood vessels, osteoclasts dissolve the calcified cartilage
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Interstitial growth
bones increase in length, can stop
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Appositional growth
bones increase in width through life
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Bone remodeling
occurs throughout life-10% per year, responds to stress
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