Bone As A Tissue

Question 1

Paget’s disease

Answer 1

Increases the number and size of osteoclasts (and contain viral particles)
Even greater increase in osteoblasts –> thickened irregular bone, less useful strengthening bone
Affects older people, possible to treat with bisphosphonates that bind calcium to disrupt osteoclasts function

Question 2

Rickets

Answer 2

Lack of vitamin D3 or its action (such as defects in receptor, or hydroxylase)
Failure to absorb calcium, bones deficient in calcium
Legs bend as bones weaker, growth is stunted
Vitamin D is essential for chondrocyte maturation in epiphyseal plate. When lacking, results in disorganised cartilage columns and inhibits matrix calcification

Question 3

Osteoporosis

Answer 3

Lack of oestrogen post menopausally, in smokers or alcoholics
Oestrogens and bisphosphonates bind to calcium a dn disrupt osteoclast activity
Means increased activity of osteoclasts or decreased activity of osteoblasts
Weakened bones that are more likely to fracture, characteristically exaggerates kyphosis of the thoracic spine

Question 4

Achondroplasia

Answer 4

Autosomal dominant mutation in FGFR3
Necessary for proliferation zone
Receptor switched and cells come out of the cycle at proliferative zone too early, shorter bones
At epiphyseal plate, affects long bones, hence characteristic normal sized head and hands

Question 5

Laron syndrome

Answer 5

IGF-1 receptor mutated
Means growth hormone cannot function
Save rely affects a height and levels of IGF
Widespread lack of growth, hence short stature
IGF is the mediated of the anterior pituitary hormone somatotrophic hormone

Question 6

Osteogenesis Imperfecta

Answer 6

Brittle bones disease
Mutation of type I collagen
Bones break easily and become deformed
As collagen is weakened reduces the flexibility of the bone