Bone Growth Flashcards
What tissue forms the blueprint of the skeleton
Cartilage (bone later replaces this)
Define endochondral ossification
The process of forming bone from cartilage during growth in utero
Describe step 1 of endochondral ossification
Nucleation of CaCO3 minerals in centre of cartilage
Describe step 2 of endochondral ossification
Blood vessels form on surface, bring fibroblast, differentiate into OB
Describe step 3 of endochondral ossification
OB begin to lay down bone
Describe step 4 of endochondral ossification
Blood vessels become inside bone
Describe step 5 of endochondral ossification
OB create more bone in centre = create bone shaft
What is the location of primary ossification?
In the diaphyses (shafts)
What is the secondary site of ossification?
In the epiphyses
What is the growth plate known as?
The epiphyseal plate
What is the function of the growth/epiphyseal plate?
To enable lengthwise bone growth throughout childhood, as the diaphyses is not not attached to anything and thus can continue to grow
What process occurs in bones from about puberty onwards?
The epiphyses start to fuse with the diaphyses
Define appositional growth
Bone growth widthwise
What role do osteoblasts play in appositional growth?
OB adds bone matrix to the bone surface, create extra lamellae
What role do osteoclasts play in appositional growth and what is the purpose of this?
OC removes bone from the medullary cavity, ensuring that the cavity also gets wider and isn’t too dense (heavy and hard to move)
Define bone homeostasis
The balance of OB and OC activity
Bone is constantly being formed/destroyed - why is this?
to allow body to…
- mobilise minerals from the matrix
- respond plastically to stress
How are minerals mobilised from the bone, and how is homeostasis maintained?
Bone tissue broken down, ions into bloodstream, new bone formed simultaneously = maintains homeostasis
Why is bone able to respond plastically?
Shape change possible throughout life based on stress, common movements
What are some requirements to maintain bone homeostasis?
adequate Ca in diet, regular exercise
Name 2 conditions that are the result of imbalance of OB/OC activity
Osteopenia (OC > OB activity)
Osteoporosis (same issue, but has become clinically significant)
Describe 2 characteristics of osteopenia
- compact bone is thin and weak
- bone becomes fragile, brittle, and is more likely to fracture
Name 3 risk factors for osteopenia
- women (OC activity linked to oestrogen)
- lack of exercise
- poor diet (salt, alcohol consumption)
