rheumatology Flashcards
what markers can measure the rate of collagen formation in the blood
P1NP and P1CP
what is cathepsin k
enzyme which breaks down collagen; secreted by osteoclasts
what type of collagen are bones, ligaments, tendons, and skin made of
type 1
what does type 4 collagen make
the basement membrane
what does type 10 collagen make
the growth plate
what are the different areas of the bone
epiphysis, metaphysis, diaphysis
woven vs lamellar bone
woven bone is made quickly and is disorganised
lamellar bone is made slowly and it is more organised. lamellar bone is remodelled woven bone.
what are osteons
cylinders of lamellae which contain the blood and nerve supply in the centre in a canal called the harversian canal
what is the difference between the type of bone in the epiphysis and the diaphysis
the epiphysis has trabecular bone and the diaphysis has cortical bone
where do osteoblasts originate from
mesenchymal stem cell
what is the function of alkaline phosphatase (ALP) in bone and why do you measure it in the blood
Alkaline phosphatase is produced by osteoblasts. It facilitates the deposition of minerals (mainly calcium and phosphate) in the bone matrix. The enzyme helps with bone formation and remodelling.
Measuring alkaline phosphatase levels in the blood can be a diagnostic tool to assess bone health. Elevated levels of alkaline phosphatase may indicate increased bone turnover, as seen in conditions such as bone growth (during periods of rapid bone growth, like adolescence) or in diseases that affect bone metabolism, such as Paget’s disease, osteomalacia, or certain bone tumors.
why do you get hyperexcitability in hypocalcaemia
Calcium contributes to setting the threshold for action potentials because calcium maintains a constant background gradient and the action potential is triggered by entry of sodium into the cell. When calcium levels are low, the threshold may be altered, making it easier for nerve cells to reach the threshold and generate action potentials.
where in the nephron is most calcium reabsorbed
in the proximal convoluted tube
FGF-23 function and what is it produced by
regulates Vit D levels. FGF-23 decreases Vit D to decrease phosphate gut absorption and also increases renal phosphate excretion
it is secreted by osteocytes
if you have a low calcium diet will you absorb less calcium?
no. you will synthesise more Vit D3 (calcitriol) so that you can absorb more Ca from your diet
effect of PTH on serum phosphate levels
decreases serum phosphate levels –> more excretion of phosphate in DCT
what is osteoid
unmineralised bone tissue which is secreted by osteoblasts and needs to become mineralised
interstitial vs appositional growth and why is it relevant
interstitial –> from within –> growth in length
appositional –> from the outside –> growth in width
bones grow like this so that they don’t increase in weight. they are broken down from within by osteoclasts whilst they are being built from the outside by osteoblasts
what is the process of how bones are built
formation of cartilage model from hyaline cartilage by chondroblasts
you get primary ossification in diaphysis and secondary ossification in epiphysis
ossification slowly starts replacing cartilage
fusion of growth plates marks end of growth
how does cartilage get its nutrients
diffusion
what is the ossification of the growth plate called
endochondral ossification
what is the ossification of the bones of the skull called
intramembranous ossification
why is exercise physiologically good for bone
the stress form exercise downregulates osteoclast activity –> less chance of osteoporosis
what are the red flags for bone cancer
bone pain (worse at night)
pathological fracture
soft tissue swelling