BIOS 251 Week 6 Case Study: Bone

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Chamberlain University

BIOS-251 Anatomy & Physiology I

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Week 6 Case Study: Bone

There are four types of cells involved in bone tissue generation. The first type is osteogenic cells, which originate from embryonic mesenchyme. These cells multiply and eventually give rise to osteoblasts, the bone-forming cells. Osteoblasts are responsible for synthesizing the organic components of bone and promoting its mineralization (Saladin, Gan, & Cushman, 2021). Additionally, osteoblasts have an endocrine function, secreting osteocalcin, which stimulates insulin secretion from the pancreas, increases insulin sensitivity in adipocytes, and limits the growth of adipose tissue. Osteoblasts also play a crucial role in bone-building, a process known as osteogenesis. They form rows in the endosteum and inner layer of the periosteum. Stress and fractures trigger mitosis, increasing the number of osteoblasts to repair the damaged bone (Saladin et al., 2021).

Once osteoblasts become trapped in the bone matrix they produce, they transform into osteocytes. Osteocytes communicate with other osteoblasts and osteocytes through gap junctions, facilitating the exchange of nutrients and metabolic waste. Their functions include bone matrix resorption and deposition, maintenance of bone density, and regulation of calcium and phosphate levels in the blood (Saladin et al., 2021). The fourth cell type is osteoclasts, which are responsible for dissolving bone tissue. These cells have a ruffled border that increases their surface area, improving their efficiency in bone resorption (Saladin et al., 2021).

BIOS 251 Week 6 Case Study: Bone

The process of fracture repair involves four key steps: hematoma formation, bone generation, bony callus formation, and bone remodeling. Initially, blood vessels tear, forming a blood clot or hematoma at the fracture site. This seals the blood vessels and results in the death of nearby bone cells. Over a few days, capillaries grow into the hematoma, and phagocytic cells remove dead tissue (Boundless, 2021). Fibroblasts produce collagen fibers that connect the broken bone ends, while osteoblasts begin forming spongy bone. The fibrocartilaginous callus is eventually replaced by a bony callus of spongy bone, firmly joining the broken bone ends within two months (Boundless, 2021). The final step, remodeling, involves osteoclasts and osteoblasts reshaping the bony callus to restore its original form (Boundless, 2021).

The epiphyseal plate, responsible for longitudinal growth in long bones, plays a significant role in fractures affecting growth plates. A fracture in this area can result in the bone healing crooked, shorter, or longer than expected (OrthoInfo, 2021). Based on the description, the fracture in this case appears to be a stable fracture. In stable fractures, the broken bone ends align correctly and are only slightly displaced. Since the injury involved a tibial fracture without any signs of bone shattering or breaking through the skin, it is consistent with a stable fracture (OrthoInfo, 2021).

References

Boundless. (n.d.). Boundless Biology. Lumen. Retrieved October 11, 2021, from https://courses.lumenlearning.com/boundless-biology/chapter/bone/

Fractures (broken bones) – OrthoInfo – AAOS. (n.d.). OrthoInfo. Retrieved October 11, 2021, from https://orthoinfo.aaos.org/en/diseases–conditions/fractures-broken-bones/

Growth plate fractures – OrthoInfo – AAOS. (n.d.). OrthoInfo. Retrieved October 11, 2021, from https://orthoinfo.aaos.org/en/diseases–conditions/growth-plate-fractures/