University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

398

Pages:

2
Author:

Mariam A. A.

Bone remodelling ● ● ● ● ● Occurs on a daily basis in response to everyday stresses to maintain the strength and homeostasis of the bone Activity of the osteoblasts (bone deposition) and osteoclasts (bone resorption) In children: osteoblasts > osteoclasts When the epiphyseal plate completely replaced: osteoblasts = osteoclasts Old age: osteoblasts < osteoclasts What triggers osteoblast activity (encourages bone growth) ● Physical stresses (exercise) ● Vitamin D and K (calcium absorption and retention) What triggers osteoclast activity (encourages bone deterioration) ● Sedentary lifestyle ● Low calcium → body eats into the bone to release more calcium into the bloodstream ● =increased risk of osteoporosis Making new bone = bone deposition Breaking down osseous tissue = bone resorption Describe the repair process of bone repair 1. Repair in response to injury (fracture) 2. Blood vessels rupture and bleed, a hematoma (blood clot) forms which triggers an inflammatory response 3. Fibroblasts and chondroblasts enter the haematoma (soft callus formation) ● Fibroblasts deposit collagen to make dense irregular connective tissue to try to infiltrate the broken bone ● Osteoblasts convert back to chondroblasts and secrete matrix into the space (form cartilage) ● Makes gelatinous material → soft callus (cartilage from the chondroblasts) ● Soft callus = fibroblasts (secrete collagen = strength) and chondroblasts (secrete hyaline cartilage fibres) fill the hematoma which then forms into the soft callus 4. Osteoblasts enter the callus and replace cartilage with bone ● Chondroblasts go back to being osteoblasts → secrete organic matrix into the space and harden into bone tissue ● Soft callus is replaced by hard callus (bone collar) around the external surface of the fracture area ● Osteoblasts replace the cartilage callus with a bone callus = primary bone (not as strong but better than cartilage) 5. Bone resorption and deposition ● Osteoclasts come in and hollow out the medullary cavity and osteoblasts and osteoclasts work together to smooth out the hard callus, try to mend any scars ● Primary bone replaced with secondary bone = has more strength