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Osteoclasts break down bone tissue, and along with osteoblasts and osteocytes form the structural components of bone. In the hollow within bones are many other cell types of the bone marrow . Components that are essential for osteoblast bone formation include mesenchymal stem cells (osteoblast precursor) and blood vessels that supply oxygen and ...
Osteoclasts lie in small cavities called Howship's lacunae, formed from the digestion of the underlying bone. The sealing zone is the attachment of the osteoclast's plasma membrane to the underlying bone. Sealing zones are bounded by belts of specialized adhesion structures called podosomes.
The human body is in a constant state of bone remodeling. [4] 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. [5] Bone is resorbed by osteoclasts, and is deposited by osteoblasts in a process called ossification. [6]
"Bones break because of either two main reasons. One, the force on the broken is stronger than the bone can take. ... the physical structure is actually cracking in half, be it all the way or only ...
The hard outer layer of bones is composed of cortical bone, which is also called compact bone as it is much denser than cancellous bone. It forms the hard exterior (cortex) of bones. 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]
The skeletal system serves many important functions; it provides the shape and form for the body, support and protection, allows bodily movement, produces blood for the body, and stores minerals. [4] The number of bones in the human skeletal system is a controversial topic.
The cell also exhibits a reduced size endoplasmic reticulum, Golgi apparatus and mitochondria, and cell processes that radiate largely towards the bone surfaces in circumferential lamellae, or towards a haversian canal and outer cement line typical of osteons in concentric lamellar bone. [5] Osteocytes form an extensive lacunocanalicular ...
Bones are commonly described with the terms head, neck, shaft, body and base. The head of a bone usually refers to the distal end of the bone. The shaft refers to the elongated sections of long bone, and the neck the segment between the head and shaft (or body). The end of the long bone opposite to the head is known as the base.