Calcium Homestasis Flashcards
How does calcium affect muscle contraction
Decreases calcium in ECF which is free
Increases sodium perm
Depolarises Em closer to threshold
What are the results of a muscle spasm
Spontaneous contraction of RESP muscle can lead to asphyxiation
What dos calcium have to do with excitation contraction of cardiac and skeletal muscle
Action potential increase calcium perm
Entry of ECF calcium to cardiac and skeletal muscle cells trigger contractile mechanism
What dos calcium do in stumulus sec coupling
Secretory cells - increased calcium perm on repsonse to stimulus increases calcium entry - triggers release by exocytosis
Sec neurotransmitters, peptide hormones
How does calcium affect blood clotting
Acts as a co factor
What hormones as associated with calcium balance
Parathyroid hormone - raises plasma conc calcium
Calcitonin - lowers plasma conc calcium
Vitamin D3 - active form promotes calcium abs in gut
Growth hormone - favours increase bone mass
Which hormone used for calcium balance is essential for life
Parathyroid hormone
How is PTH stored
As pre or prepro hormone
What is the target for PTH
Kidney and bone
What cells prod PTH
Chief cells of parathyroid glands
What su the action of PTH
Hyper alchemical raises plasma conc calcium
What is the normal range of calcium plasm aconc
Between 2-2.5
What are e actions of PTH
Stimulates osteoclasts - promote bone resorb mobilise calcium and phosphate
Increases renal calcium abs
Decreases renal Phosohate reabs
Stimulate kidneys to conv vit d to active calcitriol to increase abs of calcium form but
What is calcitonin
Peptide form paragoliicilar cells of thyroid
Relaease in response to rising plasma calcium
Not ,UCP function though to help in pregnancy
What happens if PTH is low
Increased nerve excitability
Lead to death asphyxiation
Lowered calcium plasma concentration
Treat - infuse calcium and give vit d metabolites
What is PTH is too high
Tumours of parathyroid glands
Lead to bone demineralisation kidney stones filtered load of calcium high
Reduction in inhib effect of osteoporosis s
What is vit d def
Rickets shifted bones in children
Osteomalacia in adults bone density decreases
What is the role of calcium
Bone and teeth integrity Muscle contraction Mem stability Neurotransmitter release Secretory processes Enzyme reg
