Calcium

Question 0

Which hormones regulate calcium and phosphate?

Answer 0

Parathyroid hormone
1,25-hydroxyvitaminD (calcitrol)
Calcitonin

Question 1

What is calcium important for?

Answer 1

Hormone secretion
Muscle contraction
Nerve conduction
Inactivation of enzymes
Exocytosis

Question 2

On which organs do the hormones which control calcium and phosphate levels act on?

Answer 2

Kidneys, GI tract, bone

Question 3

What can hypocalcaemia result in?

Answer 3

Hyperexcitability of the nervous system
Paraesthesia (tingling)
Tetany (spasm and twitching)
Paralysis
Convulsions

Question 4

What can chronic hypercalcaemia lead to?

Answer 4

Bones, stones, groans and psychiatric overtones!

Kidney stones
Constipation
Dehydration
Kidney damage
Tiredness 
Depression

Question 5

What effect do each of the three hormones have on calcium secretion?

Answer 5

Parathyroid hormone (short term regulation) and calcitrol (long term) both raise calcium levels

Calcitonin is not thought to have much of an effect in humans, except in pregnancy where it is thought to maintain the maternal skeleton

Question 6

Why is phosphate important?

Answer 6

Part of ATP, so plays a crucial role in cellular energy metabolism and activation/inactivation of enzymes

Question 7

How is PTH secretion regulated?

Answer 7

Increased calcium binds to G-receptors on chief cells
Stimulates phospholipase C (PLC)
Inhibits adenylate cyclase inhibiting cAMP
Reduces PTH release

Question 8

What is parathyroid hormone related peptide?

Answer 8

A peptide hormone produced by tumours which may lead to hypercalcaemia
Similar to PTH - calcium release from bone, renal calcium excretion and renal phosphate absorption