Bone- Iittle Details Flashcards
What part of matrix is responsible for resistance to bending and compression?
The inorganic matrix
What part of matrix is responsible for resistance to pulling and tension?
The organic matrix
What is the difference between the arrangement of osteocytes in immature vs mature bone?
Immature bone : random osteocyte arrangement in trabeculae
Mature Bone: osteocytes arranged in parallel
Where does bone remodelling begin?
The reabsorption canal
In what kind of bone are Haversian and Volksmann’s canals present?
Compact bone only
What is the function of Haversian and Volksmann’s canals?
Carry blood, lymph and nerves
What is osteocytic osteolysis?
When PTH acts like osteoclasts to degrade bone by releasing HCl which breaks down minerals of bone and collagenase, which breaks down collagen of bone
What 4 vitamins are important for bone remodelling?
Vitamin D3- produces calcitonin for calcium absorption
Vitamin C- synthesises collagen
Vitamin K and Vitamin B12- holds on to calcium for bone synthesis
What is osteomalacia?
Deficiency in vitamin D in adults causes ‘rickets like symptoms’
Lower mineralisation and increase osteoids means bone isn’t as strong as it should be
Can be caused by kidney disease, lack of sunlight, surgery to the stomach
Drugs: phenytoin (epilepsy drug) prevents vit D absorption
What is primary type 1 osteoporosis?
Affects post menopausal women due to loss of oestrogen
Increase osteoclasts number increases holes in trabeculae
What is primary type 2 osteoporosis?
Affects men and women over 70 yrs
Loss of osteoblasts activity due to loss of oestrogen and androgen
What is secondary osteoporosis?
Use of glucocorticoids and anabolic steroids causing bone loss
Or: malnutrition, prolonged immobilisation and weightlessness
What is achondroplasia?
Inherited FGF3 receptor gene mutation- FGF normally promotes collagen formation
Affects endocondrial ssification, therefore long bone formation
Causes short stature, but normal head and torso
