Calcium homeostasis Flashcards
What are the 3 hormones that regulate Ca conc?
Metabolites of vit D
Parathyroid hormone
Calcitonin
What is hypocalceamia?
Low calcium conc.
What is hypercalceamea?
High calcium conc.
Where is parathyroid hormone manufactured and what does it respond to?
Chief cells
Hypocalaemia
What are CaSR’s responsible for
Extracellular homeostasis
Nutrient sensors on the parietal and G cells
Enzyme secretion of alpha and beta cells
Where are PTH receptors expressed
Osteoblasts in bone and in proximal and distal tubules of the kidney
What are PTH responsible for?
Increasing extracellular Ca conc.
What is metabolites of vit D converted to and what by?
Active state by hydroxylations
Where is calcitonin manufactured and what does it respond to?
Thyroid gland
Hypercalcaemia
What is inorganic phosphate homeostasis regulated by?
Phosphatonins, PTH and calcitrol
What is FGF23 secreted by and what does it stiumlate?
Osteocytes and is upregulated when plasma phosphate conc increases
Stimulates phosphate loss in urine.
What are the 2 calcium binding proteins
EF and C2 domain contains proteins
What are the 2 calcium buffering proteins
Calnexin- ER
Calsquestrin-sarcoplasmic reticulum
What are the points of entry for calcium
Ca2+ ATPases
Voltage-gated Ca2+ channels
Na2+/Ca2+ exchanger
Permeability transition pore
What are the 2 types of Ca2+ATPases and what do they do
PMCA- plasma membrane, Moves one Ca out for every ATP hydrolysed
and SERC- Sercoendoplasmic reticulum- moves 2 ca in for every 2 ATP hydrolysed
