calcium physiology Flashcards
give some examples of the role calcium plays in the body
- bone and tooth structure
- mineral store
- action potentials in cardiac muscle
- membrane potentials
- 2nd messengers
- blood clotting
which 3 substances maintain calcium homeostasis?
- parathyroid hormone
- calcitonin
- Vit d
when is parathyroid hormone secreted?
when plasma calcium levels are low
how does parathyroid hormone work to increase plasma calcium levels?
- increase bone resorption
- increase calcium uptake by kidneys (decreased PO4 resorption)
- increase calcium uptake from intestine (assisted by vii d)
when is calcitonin secreted?
in response to high plasma calcium levels
how does calcitonin act to lower blood plasma?
- increase bone formation
- decrees calcium resorption in kidneys
does calcitonin play a major role in calcium homeostasis?
no
what role does vit d play in calcium uptake?
vit d is needed to absorb calcium
which hormones increase bone formation and bone mass?
- calcitonin
- growth hormone
- IGF-1
- insulin
- oestrogen
- testosterone
which hormones increase bone resorption and decrease bone mass?
- cortisol
- parathyroid hormone
- thyroid hormone
what role do osteoblasts play in the mineralisation of bone by calcium salts?
synthesise and secrete collagen fibres forming matrix later mineralised by calcium salts
raised calcium levels is known as?
hypercalceamia
decreased calcium levels is known as?
hypocalcaemia
what is tetany?
A condition that is due usually to low blood calcium
what may cause hypocalceamic tetany?
- decreased calcium intake
- excessive calcium loss
- alkalosis (low calcium)
