Calcium Flashcards
which mineral tightly regulates levels of calcium
phosphorous
how much ECF calcium is biologically active
50%
small amount is complexed and the rest in protein bound
what type of crystals are formed by salt precipitation in bone remodelling
hydroxyapatite
mainly calcium phosphate salt
what are the physiological functions of calcium
controls membrane excitation
excitation - contraction coupling
haemostasis
stimulus - secretion coupling
second messenger and enzyme activity
maintenance of tight junctions between cells
bone formation
why must Ca2+ plasma conc be tightly regulated
potential detrimental effects of free calcium
death due to muscle asphyxiation
three main hormones of Ca2+ regulation
parathyroid hormone
vitamin D
calcitonin
parathyroid glands anatomy
4 rice-grain sized glands
2 posterior to each lobe of the thyroid
what triggers PTH secretion
decrease in free Ca2+ conc in the ECF
effect of PTH on kidneys
increases Ca2+ reabsorption
stimulates active Vit D formation
decreases phosphate reabsorption
what is the effect of PTH on bone
stimulates active osteoclasts increasing resorption increasing by causing release of hydroxyapatite
effect of Vit D on intestine
increases Ca2+ absorption
where is calcitonin secreted from
in response to what
parafollicular (C) cells of the thyroid gland
in response to high conc of Ca2+ in the EFC
what would happen if PTH had no effect of phosphate levels
it would not be secreted and the increased Ca2+ conc would simply crystalise with the phosphorus
effects of calcitonin on the kidneys
decrease phosphate reabsorption
decrease Ca2+ reabsorption
effects of calcitonin on bone
oppose action of PTH on osteoclasts
decreases resorption
decreased Ca2+ release
what is the active form of vitamin D
D3 calcitriol
what are the sources of vitamin D forms
D2 and D3 come from diet
D3 is the only one synthesised in the skin using UV radiation
where is inactive vitamin D stored
liver
where is active vitamin D created
kidney
effects of vitamin D on kidneys
increased phosphate reabsorption
increased Ca2+ reabsorption
effect of calcitonin on the intestine
none
effect of vitamin D on the intestine
increased phosphate reabsorption
increased Ca2+ reabsorption
effect of vitamin D on bone
promotes PTH action on osteoclasts
increased resorption
increased release of Ca2+ into plasma
where does reabsorption, absorption, and resorption occur
reabsorption - kidney absorption - intestine resorption - bone
effects of PTH hypersecretion
hypercalcemia and hypophosphatemia
moans (depressions and anxiety - lmao)
bones (bone pain - osteoporosis)
stones (de la kidney)
groans (abdominal pain, nausea and vomiting)
where is pain caused by kidney stones
sides and back below ribs
treatment options of kidney stones
small: drink water, pain relievers, relaxation of ureter
large: sound waves to break up stones, surgery, parathyroid gland surgery
what bone disorder results from not enough calcium
osteoporosis
effects of PTH hyposecretion
hypocalcemia and hyperphosphatemia
muscle cramps and twitches from motor nerves, respiratory muscles go into hypercalcaemic spasm
death.
what is the treatment for hypocalcaemia
synthetic PTH (doesn’t exist)
active Vit D and high calcium diet and supplements
what happens in vitamin D deficiency
impaired intestinal absorption of Ca2+ leading to PTH secretion to maintain Ca2+ conc at the expense of bones
bone becomes some and deformed due to pressures of weight bearing
rickets - children
osteomalacia - adults
