Osteoporosis Flashcards
What are the two main types of bone?
- Cortical bone
- Trabecular bone
What percentage of the body is made up of the cortical bone?
80%
What percentage of the body is made up of the trabecular bone?
20%
What is the cortical bone?
- Compact bone that forms the dense outer supporting structure
What is the trabecular bone?
- Spongy bone that forms the inner supporting structure
- Composed of a lattice or network branching bone spicules or trabecular and spaces filled with bone marrow
Bone is a static tissue. True or False
False
What is the bone renewal process called?
Remodelling - Old bone removed and replaced by new bone
What are bone resorbing cells called?
Osteoclasts
What are bone forming cells called?
Osteoblasts
What are osteoblasts?
- Fill in bony cavity with bone matrix
- Release cytokines to attract osteoclasts
What are osteoclasts?
- Release proteases which dissolve the bone mineral matrix and collagen and clear damaged bone
- Release chemicals that attract osteoblasts
Bone remodelling is under the control of what factors?
- Systemic hormones (parathyroid hormone and sex hormones (oestrogen and androgens))
- Activated vitamin D
- Cytokines (Interleukin-1 and Interleukin-6/ TNF-alpha/ GCSF)
- External factors
What is bone mass determined by:
- Peak bone mass that was attained at around age 30 years
- Rate of bone loss that commences in 4th decade
What is osteoporosis?
- Is a common metabolic bone disease characterised by reduction in bone mass per unit volume (thinning of the bones) that occurs with increasing age
- Micro-architectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture
Why is genetics involved in rate of bone loss?
Genetics factors (approx 75%)
- More likely to have osteoporosis if strong family history
- Possible involvement of several genes investigated: Vitamin D receptor gene / Oestrogen receptor / Interleukin (IL) -6 gene
