Metabolic Bone Disease Flashcards
1
Q
What are the different bone cell types ?
A
- osteogenic cell
- osteocyte
- osteoblast
- osteoclast
2
Q
Describe osteogenic cell
A
- stem cells
- develop into an osteoblast
3
Q
Describe an osteocyte
A
- most abundant cell type in mature bone
- found in bone matrix - lacunae
- involved in mechanical-transduction
- allows surrounding cell to accommodate mechanical stress
- regulate fluid flow into bone
4
Q
Describe an osteoblast
A
- forms bone tissue
- deposits new collagen & minerals
- once it finishes this task it has 1 of 3 fates
1. flattens& becomes a cell that lines the bone surface
2. becomes an osteocyte
3. undergoes apoptosis
5
Q
Describe osteoclast
A
- multi-nucleated cell
- responsible for bone resorption, repair & remodelling
- uses lysosomal & hydrogen ions to breakdown bone matrix
6
Q
What are the small microscopic spaces osteocytes occupy called ?
A
Lacunae
7
Q
What is the function of bone remodelling ?
A
- to adjust the architecture to meet the changing needs of the body
- also helps repair microdamage in bone matrix
- aids in maintaining plasma calcium homeostasis
8
Q
Describe Urinary Hydroxyproline
A
- breakdown product of collagen
- used to monitor bone resorption
- urinary excretion is influence by diet
9
Q
Describe Bone Alkaline Phosphatase
A
- bone-specific isoform of alkaline phosphatase
- glycoprotein which is found on the surface of osteoblasts
- reflects the biosynthetic activity of these bone- forming cells
- produced by cells lining the bile canaliculi
10
Q
Describe Osteocalcin
A
- synthesised by osteoblasts
- an important non-collagenous constituent of bone-measured using an immunoassay
- sensitive indicator of osteoblast activity
11
Q
Describe Osteomalacia & Rickets
A
- defective bone mineralisation in adults & children
- deficiency in Vit D
12
Q
What are the lab tests for Osteomalacia?
A
- vitamin D deficiency
- serum calcium falls
- appropriate increase in parathyroid hormone
12
Q
Describe Paget’s disease
A
- disease of the elderly
- increased osteoclast activity
- osteoblasts try to repair bone
- new bone is laid down in a disorganised way
- turnover is greatly increased
- new bone is more plastic - more malleable = deformity & pain
13
Q
Describe Osteoporosis
A
- chronic condition = bones gradually lose density or mass
- decrease in bone strength –> leads to fragile bones & prone to fracture
- treatment = biphosphonates - inhibit osteoclastic functions so they slow bone loss
14
Q
What are some risk factors for osteoporosis ?
A
- family history
- over 50
- being female
- menopause
- broken bones & height loss
