ES. Calcium Flashcards
what is calcium involved in the structure of?
bone and tooth
what does calcium store?
minerals
in terms of a second messenger, what is calcium involved in?
muscle: excitation-contraction coupling
gland secretion
non steroid hormone action
how do we maintain the concentration of calcium?
diet then absorbed in the GIT
what hormones are involved in calcium homeostasis?
parathyroid
calcitonin
vit d
where are parathyroid hormones secreted from and in response to what?
from parathyroid glands in response to low plasma
how does parathyroid hormone act to increase plasma calcium?
- increased resorption of bone (osteoclasts)
- increased calcium ion resorption in kidney (with reduction in phosphate resorption)
- increased uptake in calcium ions form the intestines (assisted by vitamin d)
where is calcitonin secreted from and in response to what?
from thyroid glands in response to high plasma
how does calcitonin lower plasma calcium?
- increased formation of bone (osteoblasts)
- decreased calcium resorption in kidney
does calcitonin play a major role in calcium homeostasis?
no as it lacks pathological effects
does calcitonin play a major role in calcium homeostasis?
no as it lacks pathological effects
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 do osteoblasts do?
synthesise and secrete collagen fibres forming a matrix layer mineralised by calcium salts
PRODUCE BONE
what are osteocytes?
osteoblasts that are trapped in the bone matrix
where do osteocytes lie and how do they contact other cells?
in bony lacunae and contact other cells via long cytoplasmic processes
what is the function of osteoclasts?
resorb bone
what are osteoclasts? (structure)
large, multinucleate cells
derived from macrophages
where do osteoclasts lie?
in depressions (howships lacunae)
what is hypercalcaemia?
raised Ca2+
what is hypocalcaemia?
reduced Ca2+
what hypocalcaemia due to?
- decreased Ca2+ intake
- excessive Ca2+ loss
- alkalosis (low Ca2+)
what effect does low Ca2+ have on nerve excitability?
what does this feel like?
increases it which feels like pins and needles/ muscle spasms
what effect does low Ca2+ have on nerve excitability?
what does this feel like?
increases it which feels like pins and needles/ muscle spasms
what can lead to hypocalcaemia?
hyperventilation (panic attack) which can cause alkalosis so decreased co2
what is the remedy for alkalosis ?
trap co2 in patients lungs so rebreathe air from a bag
what can hyperparathyroidism lead to?
osteitis fibrosa cystica = areas of demineralisation in skull and leg bones
how would osteitis fibrosa cystica in the gingiva present in a radiograph?
radiolucent
how can hypothyroidism effect the teeth?
defective mineralisation of teeth due to low blood calcium levels due to under secretion of PTH
what can a vit d deficiency lead to in adults and children?
rickets - children
osteomalacia - adults
what effect does vit d deficiency have on the uptake of calcium by the GIT?
decreases the uptake
what effect does a vitamin d deficiency have on bone?
unmineralised so lacks rigidity
what clinical consequences does a change in calcitonin levels have?
none therefor not essential for regulation of plasma
what is osteoporosis?
decreased bone mass and density
what is ostepetrosis?
increased bone mass and density
what part of the bone does osteoporosis effect?
reached thickness of cortical bone in the femur
what causes osteoporosis?
common in elderly
women earlier due to menopause
corticosteroids
nutritional deficiency
how does osteoporosis show on a radiograph?
tooth roots are indistinct
what can people with osteoporosis be prone to?
fracture and chronic infection
how does osteopetrosis effect blood supply?
reduces it
is osteopetrosis present in the mandible or the maxilla?
mandible
