Calcium Homeostasis

20 questions • 1 test • tap a section to begin

Welcome! 8.1 Calcium Homeostasis — 20 questions, CSIR-NET style.

What this test covers

  • Forms of plasma calcium; ionized vs protein-bound
  • PTH, vitamin D and calcitonin overview
  • Bone, gut and kidney in Ca2+ balance
  • Effects of pH on ionized calcium

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8.1 Calcium Homeostasis — Test 1
Q1. The physiologically active form of plasma calcium is:✓ Ionized (free) calcium
Q2. Alkalosis tends to cause symptoms of hypocalcemia because it:✓ Increases binding of Ca2+ to albumin (lowering ionized Ca2+)
Q3. The three principal hormones controlling calcium balance are:✓ PTH, vitamin D (calcitriol) and calcitonin
Q4. The largest reservoir of calcium in the body is:✓ Bone
Q5. The cells responsible for bone resorption (releasing calcium) are:✓ Osteoclasts
Q6. PTH and vitamin D both act to RAISE plasma calcium, whereas calcitonin acts to:✓ Lower plasma calcium
Q7. Match each organ with its role in calcium balance and choose the correct option.✓ A-ii, B-iii, C-i
Q8. The minute-to-minute regulation of plasma calcium is dominated by:✓ Parathyroid hormone
Q9. Hypocalcemia characteristically causes:✓ Increased neuromuscular excitability (tetany)
Q10. Hypercalcemia characteristically causes:✓ Decreased neuromuscular excitability (lethargy, weakness)
Q11. The calcium-sensing receptor on parathyroid cells detects:✓ Serum ionized calcium (to regulate PTH release)
Q12. Most of the non-ionized plasma calcium is bound to:✓ Albumin
Q13. A patient with low serum albumin may have a low TOTAL calcium but normal:✓ Ionized calcium (and no symptoms)
Q14. PTH affects phosphate by promoting renal phosphate:✓ Excretion (phosphaturia)
Q15. The bone-forming cells that deposit matrix and promote mineralization are:✓ Osteoblasts
Q16. Vitamin D's main role in calcium balance is to:✓ Increase intestinal calcium absorption
Q17. A fall in ionized calcium leads to:✓ Increased PTH secretion
Q18. The skeleton serves calcium homeostasis by acting as a:✓ Dynamic reservoir that can release or store calcium
Q19. Acidosis tends to:✓ Increase ionized calcium (less albumin binding)
Q20. Overall calcium homeostasis is maintained by coordinated action on:✓ Gut (absorption), bone (storage) and kidney (excretion)