calcium, magnesium and phosphate metabolism Flashcards
(24 cards)
why are Ca and Mg important
structure for teeth and bones
cofactor enzymes
used as intracellular signalling second messengers
neuromusclar muscle contraction and neurotransmitter release
why is Po4 important
substrate for mineralisation
metabolism of sugars
ATp and GDP
help secrete H+ ions
why is 2,3 DPG important
inorganic phosphate produced in red cells
binds to the beta chain of reduced haemoglobin (Hb), lowering Hb’s affinity for O2 and facilitating O2 release to tissues,
Po4 and DPG
low Po4 reduces ability to form DPG
moves O2 curve to lefti increasing binding affinity for oxygen
results in inadqeuate o2 release at tisues
calcium economy
bone is major pool for it
exchaned fromhere
trabecular bone
spongy matrix structure
metabolic cyle occurs here
osteoclasts
resorb bone and chomp it up
Ca, Po4 released
osteoblasts
lay down new bone
Build it up
bone anabolism
bone growth
laying down collagen and mineralisation
pos balance between things
ageing bone
catabolism
negative balance
bone broken down more
osteoporosis
metabolic bone dissease
bone mineral density falls
calcium economy and the kidney
kidney filters blood ith calcium in and resorbs it
but high levels of blood Ca and damage kiney cels
renal stones
high calcium through kidney leads to rena mechanism of stones forming
the calcium redicpiates into stones
what facilitates the absoption of calcium
Vit D
PTh
parathyroid hormone
also helps with calcium regulation
role of PTh
parathyoid gland receptors detect falling ca and Mg
PTH made as pre-pro horone then cleaved to be biologically active
PTH receptor
found in kidney
enzymatic region
makes cAMP
stimulates renal resoroption of calcium
endocrine functions of Vit D
uregulates intestinal ca transport
more bone metabolism
more renal ca erabsoption
incerased blood pressure
autocrine paracrine actions of vit D
inhibits cell proliferation
promotes cell differntiation
regulates immune system
hyperparathyrodism
excess PTH
can be due to tumour
consequences of hyperparathyrodism
- bones degraded, fractures
- kidney retains ca
- dilute urine
- kidney stones
- neuromuscular weakness
hypocalamia
not enough vit D
can be caused by kidney failure, Mag deficiency, low PTH or vit D deficiency
rickets
poor mineratlistion of bones and they become soft and bow under pressure
role of PTH
- release more calcium from bone
- excrete less Ca from kdineys
- absorp more ca in gut
