Bone resorption

Bone resorption is <a href="/facts/Resorption/PsQIN5TA">resorption</a> of <a href="/facts/Bone_tissue/pCU37jBe">bone tissue</a>, that is, the process by which <a href="/facts/Osteoclast/jHHtEQru">osteoclasts</a> break down the tissue in <a href="/facts/Bone/kwJaR6IQ">bones</a> and release the <a href="/facts/Mineral/LkUFbNmv">minerals</a>, resulting in a transfer of <a href="/facts/Calcium/hf252CC0">calcium</a> from <a href="/facts/Bone_tissue/pCU37jBe">bone tissue</a> to the <a href="/facts/Blood/03zEulkj">blood</a>.
The osteoclasts are multi-nucleated <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a> that contain numerous <a href="/facts/Mitochondria/ErHqrdJ1">mitochondria</a> and <a href="/facts/Lysosome/0mcrzJU9">lysosomes</a>. These are the cells responsible for the resorption of bone. Osteoblasts are generally present on the outer layer of bone, just beneath the <a href="/facts/Periosteum/vRlYlFgQ">periosteum</a>. Attachment of the osteoclast to the <a href="/facts/Osteon/fTFx9XDA">osteon</a> begins the process. The osteoclast then induces an infolding of its cell membrane and secretes <a href="/facts/Collagenase/IWkePfvJ">collagenase</a> and other enzymes important in the resorption process. High levels of <a href="/facts/Calcium/hf252CC0">calcium</a>, <a href="/facts/Magnesium/XyIhd2FG">magnesium</a>, <a href="/facts/Phosphate/FDGVCxUG">phosphate</a> and products of <a href="/facts/Collagen/KsyAb72K">collagen</a> will be released into the extracellular fluid as the osteoclasts tunnel into the mineralized bone. Osteoclasts are prominent in the tissue destruction found in <a href="/facts/Psoriatic_arthritis/X3onPL9T">psoriatic arthritis</a> and rheumatological disorders.
The human body is in a constant state of <a href="/facts/Bone_remodeling/eoanghIb">bone remodeling</a>. Bone remodeling is a process which maintains bone strength and ion homeostasis by replacing discrete parts of old bone with newly synthesized packets of proteinaceous matrix. Bone is resorbed by osteoclasts, and is deposited by <a href="/facts/Osteoblasts/N6mMDQvR">osteoblasts</a> in a process called <a href="/facts/Ossification/6ETh4tp8">ossification</a>. <a href="/facts/Osteocyte/nUBl8e1S">Osteocyte</a> 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.
Bone resorption rates are much higher in post-menopausal older women due to estrogen deficiency related with <a href="/facts/Menopause/b3Fz6NHb">menopause</a>. Common treatments include drugs that increase bone mineral density. <a href="/facts/Bisphosphonate/s6po5jLd">Bisphosphonates</a>, <a href="/facts/RANKL_inhibitor/bggQcUcm">RANKL inhibitors</a>, SERMs—<a href="/facts/Selective_oestrogen_receptor_modulators/nrQldde1">selective oestrogen receptor modulators</a>, hormone replacement therapy and calcitonin are some of the common treatments. Light <a href="/facts/Weight_training/FynHFusa">weight-bearing exercise</a> tends to eliminate the negative effects of bone resorption.

Bone resorption open-in-new

Bone resorption