Calcium & Bone Flashcards
what is the periodontium
tissue around the tooth
what does the periodontium compromise of
PDL
alveolar bone
gingiva (gum- incl junctional epi)
—- Cementum?
what are the functions of bone
skeletal
- protection organs
- rigidity
- movements
- attach muscles and teeth
calcium pool
contain marrow
why is it imp to know about bone
regional diff in mouth - LA bone changes in mouth - extraction ortho tooth moves osseointegration - implants biphosphonates
what is the composition of bone
65% mineral - HA
25% organic - 90% type 1 collagen an 10% ground subs
10% water
what is the alveolus
sac
little cavity
what are the components of the alveolar bone
alv bone - cortisol bone compact
basal bone - trabecular bone spongy and cancellous
what is the lamina dura
budnelbone
cribriform plate
lining alveolus tooth sits in
what are the lamellae assc with bone
circumferential
concentric
interstitial
what are the circumferential lamellae
outside of most cortisol bone
what are the concentric lamellae
organised in haversian system s- osteon
what are the interstitial lamellae
remnants of old lamellae
what are the means of bone formation
endochondrol ossification
intramembranous ossification
what is endochondral ossify
cartilage –> calcified cart –> bone
what is intramembranous oddification
cold of mesenchymal tissue
osteoblasts prod osteoid matrix
woven bone
primary osteon form
what are osteoblasts
mesenchymal/ectomesnchymal
bone surface - periosteum/endosteum
prod osteoid matrix
what are osteocytes
trapped osteoblasts
cell processes
linked by gap junctions
cells vital
what are osteoclasts
haemopoeitic source - macrophage
large multinuc cells
in how ships lacunae - dissolve bone mineral - acid and break org matrix with enzymes
how freuwnet is bone turnover
continuous remodelling
resoprton
deposition
when is bone completely replaced
every 10 years
helps maintain plasma calcium levels
how si bone remodelled
cutting cone - osteoblasts
filling cone - osteoblasstst
what does remodelling result in
secondary osteons etc
how much calcium in body
1kg
99% in bone and teeth
1% body fluids
what are roles of calcium
mem perm excitation - contraction excitation - secretion hard tissue form blood clots enzyme rctaion in secretions - milk
what is quick regulation of calcium regulation
rapid exchanges between bone and ECF
what is slow regulation go calcium
intestinal abs
renal excretions
what is parathyroid hormone
essential for life release in response o falling Ca increases plasma corn of calcium prevents hypocalcaemia withdraws calcium from bone bank
what si the mechanism of PTH
fast Ca efflux to plasma - osteocytes from labile pool of Ca slow Ca efflux to plasma - bone dissolution - shift remodelling to favour resorption - osteoclasts kidney - reduced excrete of Ca
what does pTH deficiency lead to
iatrogenic PT gland
tetany
asphyxiation
what does PT hormone excess lead to
hyperplasia of PT gland
tumours
weak bones
ectopic mineralisation
what is calcitonin form
c cells on thyroid gland
what does calcitonin do
prevents calcium conc in plasma becoming high
how does calcitonin work
reduce osteocyte and osteoclast activity
reduce osteoclast numbers
what is vitamin d essential for in tim of Ca
Ca in intestine
what is vit d
prod in skin in response to sunlight on a precursor
increases Ca abs in intestine
what is BRONJ
biphsophonate related osteonecrosis of the Jaws
what are bisphosphonates used for
osteoporosis reduce rates
bone metastases
hwodoes Bisphophonates work
reduce osteoclast activity and reduce bon breakdown
what doe BRONJ do
impaired bone turnover –> exposed bone after extraction
