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An osteocyte, an oblate shaped type of bone cell with dendritic processes, is the most commonly found cell in mature bone. It can live as long as the organism itself. [ 1 ] The adult human body has about 42 billion of them. [ 2 ]
Osteocyte activity plays a key role in this process. Conditions that result in a decrease in bone mass can either be caused by an increase in resorption or by a decrease in ossification. During childhood, bone formation exceeds resorption. As the aging process occurs, resorption exceeds formation. [5]
The cortical bone gives bone its smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult human skeleton. [10] It facilitates bone's main functions—to support the whole body, to protect organs, to provide levers for movement, and to store and release chemical elements, mainly calcium.
Feedback from physical activity maintains bone mass, while feedback from osteocytes limits the size of the bone-forming unit. [33] [34] [35] An important additional mechanism is secretion by osteocytes, buried in the matrix, of sclerostin, a protein that inhibits a pathway that maintains osteoblast activity. Thus, when the osteon reaches a ...
The above dataset provides a nested list of cell groups with over 400 human cell types with cell count, cell size, and aggregate cell mass (biomass). See Dataset S1, Cell Group by Subgroup Tab, in this reference. [3]
Bone canaliculi are microscopic canals between the lacunae of ossified bone.The radiating processes of the osteocytes (called filopodia) project into these canals. These cytoplasmic processes are joined together by gap junctions.
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in fracture risk. It is the most common reason for a broken bone among the elderly . [ 3 ]
Tartrate resistant acid phosphatase positive osteoclast in cell culture Illustrated cross-section of an activated osteoclast. An osteoclast is a large multinucleated cell and human osteoclasts on bone typically have four nuclei [5] and are 150–200 μm in diameter.