calcium and osteoporosis Flashcards
role of Ca2+
changes excitability of cells, hypocalcaemia causes spasm and hypercalcaemia causes arrhythmias
cortical bone
outside of the bone, very dense, concentric osteocyte rings arranged around a central canal
bone turnover
- osteoclast recruits other OCs
- OCs dissolve bone and release IGF and TGF beta to attract OB precursors
- these mature to osteoblasts
- they fill the cavity and release RANKL
- this increases osteoclast differentiation and osteoprotegerin
what does parathyroid hormone do
releases Ca2+ from bone
- fast exchange: efflux of calcium from labile pool by binding to receptors on OCs and OBs causing cAMP increase
- slow exchange: PTH activates OBs to release RANKL to activate OCs
release of parathyroid hormone
parathyroid glands release PTH when plasma Ca2+ falls
release of calcitonin
C cells in thyroid glands when plasma Ca2+ increases
role of calcitonin
decrease plasma calcium, inhibits OB activity and Ca2+ resorption in the kidney
synthesis of vitamin D
synthesised in the skin by sunlight or taken in the diet
role of vitamin D
pre-hormone that once metabolised increases Ca2+ absorption in the GIT, acts at nuclear receptors
osteoporosis
metabolic bone disease characterised by a reduction in bone mass per unit volume that occurs with increasing age
T score
number of standard deviations by which the individuals bone mass density differs from the mean peak
T score results
normal - >-1
osteopenia - -1 - -2.5
osteoporosis - <-2.5
established osteoporosis - <2.5 & fracture
primary osteoporosis
age related
secondary osteoporosis
related to another medical conditions or drug induced
symptoms of osteoporosis
spinal collapse, height loss, pain, deformation, vertebrate, wrist NOF break
