Calcium regulation Flashcards
what 3 forms does calcium exist in, in plasma?
- free ionized species (active)
- bound to serum proteins (albumin)
- complexed with organic anions (citrate, oxalate)
What is the result to nerves of hypo and hyper calcaemia?
hypo= more excitable hyper= less exictable
What affects does hypercalcaemia have?
- moans (tirednes and depression from less excitable nerves)
- stones (kidney stones)
- abdominal groans (constipation, abdo pain)
- also polyuria and dehydration and kidney damage
What 2 hormones are released when Ca2+ is low?
- PTH
- Calcitriol
Describe the short and long term regulation of a low Ca2+
- short term: PTH released, more bone resorbtion and kidney resporbtion, also calcitriol activation
- long term: calcitriol activated means more Ca2+ resorbtion in gut
What hormone decreases serum Ca2+ in animals but has little/ no effect in humans?
calcitonin
Where are calcitonin and PTH released from?
calcitionin is from C cells of thyroid gland
PTH is from cheif cells of parathyroid gland
How is calcitriol synthesised?
precursor can be made from skin, using sunlight
also precursor from dairy products
both hydroxylated twice when PTH is high to make cacitriol
What may cause hypercalcaemia? (3)
osteolytic bone tumours
squamous tumour of lung, head, prostate or breast secreting PTH related peptide
parathyroid adenoma (primary hyperparathyroidism)
What is the difference in actions of PTH and PTHrp?
PTHrp wont activate calcitriol
What can cause hypocalcaemia?
vit D deficiency (low meat diet or lack of sun exposure)
chronic renal disease (cannot make calcitriol)
What are the symptoms of hypocalcaemia?
tingling in hands and feet, tentanus causing flexion of wrist, eppilepsy- also symptoms due to cause
What is the difference between osteomalacia and osteoporosis?
- osteomalacia is good one density but poor quality (less mineralised- less hydroxyapatite crystals)
- osteoporosis is less bone density due to increase osteoclast of decreased osteoblast activity
