bone growth, remodeling and repair. a. A discussion about bone growth should beg
ID: 3520467 • Letter: B
Question
bone growth, remodeling and repair.
a. A discussion about bone growth should begin with a comparison of intramembranous bone growth and endochondral bone growth. Be certain to review the types of cells involved (don’t forget the role of cartilage) and the location of bone growth.
b. A discussion about remodeling should include the bone cells involved and what they do, as well as a mention about remodeling in response to stress.
c. A discussion about repair should list the steps in bone repair and the cells involved.
Explanation / Answer
bone ossofication is of two types. osiification means laying down of new bone material by osteoblasts resulting in formation of body tissues .
As we know bone osiification is of two types.
Endochondral osiification and intramembranous osiification.
Endochondral osiification:-
it's essential for the formation of long bones like femur and the irregular bones with flat ends .
endochondral ossification is distinguished from intramembranous osiification by presence of cartilage during endochondral ossification .In endochondral ossification bone develops by replacing hyaline cartilage .cartilage doesnot become bone rather serves as template to be completely replaced by new bone.
intramembranous osiification;- it primarily occurs during the initial formation of flat bones of our skull it's also responsible for forming our jaw and clavicles or collar bones. in intramembranous osiification bone is formed from a specific type of connective tissue known as mesenchymal connective tissue.they are not differentiated . during intramembranous ossification compact and spongy bone develops directly from sheets of mesenchymal connective tissue.
b .bone remodelling is a lifelong process in which mature bone tissue is removed from Skelton and formation of new bone takes place .it also controls the reshaping or replacement of bone following injuries .
After appropriate signalling osteoclasts move to absorb the surface of the bone and then deposition of bone by osteoblasts takes place .Together these two cells responsible for bone remodelling are reffered as basic multicellular unit BUM and it's duration is known as bone remodelling period .
osteogenic cells develop into osteoblasts and are located in deep layers of the periosteum and the marrow.
c. A broken or fractured bones undergo repairment having four stage .
1.Hemotoma formation:- blood vessels in broken bone tear and haemorrhage and hemotoma is formed. Clotting process seal severed blood vessels .nutrient deficient bone cells die .
2.bone generation .:- After few days of fracture hemotoma is formed and dead cells are removed .the fibroblasts and osteoblasts enter the area and begin to reform the bone.collagen is produced by fibroblasts which connect broken bone ends .repair tissue between broken bone ends is composed of hyaline and fibrocartilage. so called fibrocartilaginous callus.
3.Formation of bony callous:- fibrocaetilaginous callus is converted into callus of sponge bone .it takes almost 2 months for joining broken ends of bones.
4.bone remodelling:- bony callus is remodelled by osteoblasts and osteoclasts. compact bone is added to create bone tissue similar to original bone .it takes several months .
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