Bone turnover Flashcards
1
Q
Physiological functions of bones
A
- structure
- locomotion
- protection
- support calcium and phosphate homeostasis
- hematopoiesis (production of red blood cells)
2
Q
Two key anatomical regions of long bones
A
diaphysis (shaft) and epiphysis (where they connect)
epiphyseal plate sits between these regions
3
Q
What are osteoblasts
A
- bone forming cells
- differentiate from mesenchymal precursors
4
Q
What are osteoclasts
A
- bone-resorbing cells
- differentiate from haemotopoetic stem cells
5
Q
Activation of osteoclasts
A
osteoblasts stimulate activation of themselves and osteoclasts
6
Q
Osteoclast function in trabecular bone
A
- Howship’s lacuna (cavity)
- depression within the bone, oestoclasts has released compound that will reabsorb the bone from the wavy part of osteoclast
7
Q
Osteoclast function on cortical bone
A
- create a cutting cone and move through the longitudinal axis of the bone (go down the length of the bone mainly due to mechanical stress)
8
Q
Loss of RANK
A
- autosomal recessive osteopetorosis
- failure of osteoclast to resorb bone
- radiologically - really dense bone - no hollow core just lump of bone
- in response to RANK ligand there is upregulation of osteoblasts
9
Q
Diabetes-associated osteoporosis
A
insulin is osteogenic (stimulates the deposition of bone)
- in T1DM, insufficient insulin leads to loss of osteoblast stimulation and bones become susceptible to osteoporotic breaks
10
Q
Glucocorticoid-associated osteoporosis
A
- decrease absorption of calcium across small intestine (important for increasing extracellular calcium)
- induce osteoclastogenesis and bone resorption
- suppress development of osteoblasts
11
Q
Function of osteoblasts
A
- secrete type I collagen and alkaline phosphatase to form osteoid which is mineralised by calcium phosphate to form hydroxyapatite
12
Q
Function of osteoclasts
A
- release acid and proteolytic enzymes to degrade collagen and matrix proteins in bones
