Osteoblast Essay

One of the key elements of regulating skeletal growth is the Osteoclasts. The Osteoclasts are responsible for initiating the bone remodeling cycle. Blood vessels and nerves are able to penetrate the bone once the chondrocytes die

Osteoblast- cells which build bone by removing calcium and phosphates form the blood in the presence of the enzymes alkaline phosphates secrete by

Osteopetrosis is a rare, genetic disease that causes extremely dense and brittle bones. This is because individuals affected with osteopetrosis do not have normal osteoclasts, which bones need to work correctly. Healthy bones require properly functioning osteoblasts and osteoclasts. Osteoblasts are responsible for making new bones and osteoclasts are bone cells that are responsible for bone resorption, which is the breaking down of bones and providing space for new bone marrow to grow. An individual with osteopetrosis has osteoclasts that do not function properly, therefore their bones are not healthy (Stocks, Wang, Thompson, Stocks, & Horwitz, 1998).

What is osteoporosis exactly? Literally, osteoporosis means “porous bone”. Derived from oste/o, meaning bone, and –porosis, meaning the condition of being porous. It is an imbalance between bone resorption and bone formation. Clinically defined as a disorder characterized by compromised bone strength leading to an increased risk of fracture (Lane, 2006). Normal bone structure includes an extracellular matrix with mineralized and non-mineralized components, which gives the bones their mechanical properties, as well as collagen and mineralized osteoid cells. Calcium concentration is extremely important is determining the compressive strength of the bone (Bethel, 2015). The structure of bone in an individual with osteoporosis has lost mineralization and collagen due to a decrease in the production of these components as a result, the bones become porous and brittle. Bone is living tissue, constantly being broken down and reformed through out life. Derived from

Longitudinal bone growth occurs at the epiphyseal plate, which is a thin layer of cartilage between the epiphyseal and metaphyseal bone at the distal ends of the long bones. Bone growth is the result of maturation, growth of chondrocytes, their production of bone matrix, and finally calcification (47). The growth plate is a complex structure consisting of different layers of cells, as shown in figure 3. The most immature cells, the stem cells, are found towards the epiphyseal end of the growth plate in the stem cell zone, or resting zone; the proliferating zone contains more mature chondrocytes and the hypertrophic zone contains the larger chondrocytes. The resting stem cells in the resting zone are recruited, whereupon proliferation and differentiation

Haematopoietic stem cells (HSC) regulate the turnover of platelets, erythrocytes and all immune cells by changing between self-renewal and differentiation to a variety of specialised cells. Osteoblasts has a major role of secretion of mineralized bone matrix proteins and cells of the osteoblast lineage regulating osteoclast differentiation. (Purton & Scadden, 2008)

Bone is a living tissue and made up of cartilage. Fibrodysplasia ossificans progressiva bone appears as normal bone tissue, but it develops in the wrong places. Osteogenesis and ossification are medical terms which refer to the formation of bone. Most bones in the human body grow and heal up after a break through endochondral bone formation, which is how FOP bones grow. Cartilage forms first and then the bone will eventually take the place of cartilage.

Osteoclasts are bone-absorbing cells that breakdown bone and assist in depositing calcium and phosphate in the blood.

Bone is surrounded by a thin membranous layer of soft tissue called periosteum (Singh, 2017). When the bone breaks it bleeds from torn ends because of the disruption of the supplying blood vessels. And quite naturally the periosteum is also torn. A fracture hematoma forms and white blood cells march in to clean up the area that is injured. The periosteum is the primary source of osteoblasts, which plays a huge role in fracture healing (Singh, 2017). After the hematoma formation, the next step is callous formation with the formation of cartilage and bone and then the remodeling phase consisting of the osteoclasts and the osteoblasts reshaping the bone to its original state (Patton, 2012).

Bone tissue is hard and has a calcified matrix (where the pores are filled with calcium) containing collagen fibers; osteocytes (mature bone cells) lie in the lacunae (cavity containing bone cells). The key functions of bone tissues are: support and protect the body structure and provide cavities for fat storage and synthesis of blood cells. Because the matrix of bone tissue is hard and rigid, the tissue is able to provide support and protection to the

Biomarkers of bone formation reflect osteoblast activity and are byproducts of collagen and non-collagenous matrix proteins ,growth factors and osteoblastic enzymes released in the circulation when bone is being formed ( Eastell and Hannon 2008). They include ALP ,bone-specific alkaline phosphatase, OC, and procollagen type I C-terminal propeptide and procollagen type I N-terminal propeptide ( Young 2012 ).

Multiple myeloma is a haematological malignancy characterised by the suppression of osteoblastogenesis and the inability to form bone8. The inhibition of the Runt-related transcription factor 2 (Runx2) which is a key transcription factor responsible for osteoblast differentiation is largely implicated in multiple myeloma4. Runx2 stimulates the generation of the bone formation markers alkaline phosphatase (ALP), osteocalcin (OCN) and collagen during early osteoblast differentiation9,10. Transgenic mice without the Runx2 gene exhibit a lack of osteoblast formation causing the arrest of both endochondral and intramembranous ossification11. The upregulation of bone resorption and a decrease in bone mass is a common feature of multiple myeloma, presenting clinically as lytic bone lesions12.

Osteoblasts will produce new bone matrix also referred to as osteogenesis. 86. Ossification the formation of a bone. 87. The vitamins A, K, and B are like a nosey neighbor because they are involved in all structures of body

The main difference between intramembranous and intracartilaginous bone formation are the primary structure from which ossification initiates and the method of bone growth. Intramembranous bone formation commences with the development of a membrane in the area of the bone to be formed. The embryonic mesenchymal cells that make up the membrane develop osteogenic cells and then osteoblasts to allow layers of bone tissue to form in the shape of the membrane. The flat bones covering the brain and some facial bones maintain a constant thickness level to allow for brain growth. As they enlarge, new bone tissue is built and removed to the internal and external surfaces and along the margins.

Osseous tissue contains specialized cells, cell products, and a fluid matrix. The distinctive solid, stony nature of bone results from the deposition of calcium salts within the matrix. Crystals of calcium phosphate account for almost two-thirds of the weight of the bone. The majority of