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a hard connective tissue containing an abundant mineralized extracellular matrix that surrounds widely separated cells
Sheath that covers bone. Consists of tough, outer fibrous layer of collagen and inner osteogenic layer of bone-forming cells.
Perforating (Sharpey) Fibers
Tufts of collagen fibers that extend from the fibrous layer of the periosteum into bone matrix. Secures periosteum to underlying bone.
Thin layer that covers the internal surface of a bone. Consists of reticular connective tissue along with cells that dissolve osseous tissue and others that deposit it.
Hyaline cartilage that separates the marrow spaces of the epiphysis and diaphysis. The zone where the bones grow in length.
Osteogenic (Osteoprogenitor) Cells
Stem cells that give rise to most other bone cells types (Osteoblasts & Osteocytes but NOT Osteoclasts).
Bone-dissovling cells found on the bone surface. Develop from bone the same bone marrow stem cells that give rise to the blood cells. Typically have 3-4 nuclei but can have as many as 50.
layers of matrix concentrically arranged around a central canal. A single lamellae would be a single layer (such as one layer of an onion)
Central (haversian or osteonic) canal
A central canal and its lamellae. The basic structural unit of compact bone.
Perforating (Volkmann) Canals
Connects the central canals that extend longitudinally through bone tissue. P. canals contain larger blood vessels and nerves which help the smaller vessels and nerve fibers in central canals communicate with the surface of the bone and the medullary cavity.
tiny, hard particles of calcium carbonate or silicon dioxide that are often shaped like spikes.
General term for soft tissue that occupies the marrow cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger central canals.
Red Bone Marrow
functions to form red blood cells, some white blood cells, and platelets; found in the cavities of most bones in infants and in the flat bones in adults
Yellow Bone Marrow
gradually replaces red bone marrow in adult bones; functions as storage for fat tissue; and is inactive in formation of blood cells.
the process of bone formation in the flat bones of the skull and mandible, where bone forms directly within mesenchyme arranged in sheetlike layers that resemble membranes.
the most common bone formation process, which involves the replacement of hyaline cartilage (developed by mesenchyme) with bone.
Cartiliage growth from within, by multiplication of chondrocytes and deposition of new matrix in the interior.
The deposition of new tissue at the surface of a bone. Causes the bone to thicken.
Wolff's Law of Bone
States that the architecture of a bone is determined by the mechanical stresses placed upon it, and the bone thereby adapts to withstand those stresses.
A crystallization process in which calcium, phosphate, and other ions are taken from the blood plasma and deposited in bone tissue, mainly as crystals of hydroxyapatite.
expresses the equilibrium position that occurs for the solubility of solids. It also expresses at what point solution would be considered to be saturated. Hydroxyapatite crystals form only when the solubility product is reached.
The process of dissolving bone that releases minerals into the blood and makes them available for other uses.
A calcium deficiency. Causes excessive excitability of the nervous system and leads to must tremors spasms, or tetany.
Calcium excess. Causes depression of the nervous system, emotional disturbances, muscle weakness, sluggish reflexes, and sometimes cardiac arrest.
Form of vitamin D produced by sequential action of skin, liver, and kidneys. Raises the blood calcium concentration by increasing calcium absorption in small intestine, increasing calcium resorption from skeleton (by creating more osteoclasts), and promotes reaborption of calcium ions by kidneys.
Thyroid hormone secreted when calcium concentration is too high. Lowers the concentration by Reducing osteoclast activity and stimulating osteoblast activity.
Secreted by the parathyroid glands. Is released when blood calcium is low. Raises blood calcium level by four mechanisms - 1)Raises osteoclast population, 2) promotes calcium reabosrption in kidneys, 3) promotes final step of calcitriol synthesis in kidneys, 4) inhibits collagen synthesis, thus inhibiting bone depostion.
A break caused by abnormal trauma to a bone, such as fractures incurred in falls and athletics.
A break in a bone weakened by some other disease, such as bone cancer or osteoporosis, usually caused by a stress that would not normally fracture a bone.
Spiral (Torsion) Fracture
Fracture spirals around axis of long bone, like a spiral staircase, as the result of a twisting stress such as might occur in a skiing accident.
Epiphysis is separated from the diaphysis along the epiphyseal plate; seen in juveniles.
Patches of fibrocartilage produced by chondroblasts that is part of the process of healing a fracture.
A bony collar produced by osteoblasts that forms around a fracture. Acts as a temporary splint to join broken ends or bone fragments together. Takes 4-6 weeks for it to from after injury occurs.
abnormal loss of bony tissue resulting in fragile porous bones attributable to a lack of calcium
Osteitis Deformans (Paget Disease)
Excessive proliferation of osteoclasts and resportion of excess bone, with osteoblasts attempting to compensate by depositing extra bone. Results in rapid, disorderly bone remodeling and weak, deformed bones. Usually passes unnoticed, but in some cases it causes pain, disfiguration, and fractures. Most common in males over 50.
Inflammation of osseous tissue and bone marrow as a result of bacterial infection. This disease was often fatal before discovery of antibiotics but is still difficult to treat.
Osteogenesis Imperfecta (Brittle Bone Disease)
A defect in collagen deposition that renders bone exceptionally brittle, resulting in fractures present at birth or occurring w/ extraordinary frequency during childhood. Also causes tooth deformity and hearing loss due to deformity of middle-ear bones.
Osteosarcoma (Osteogenic Sarcoma)
The most common and deadly form of bone cancer. It occurs most often in the tibia, femur, and humerus of males b/w ages of 10-25. 10% of cases metastasize to lungs or other organs. If untreated, death occurs w/in one year.
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