L51. Calcium Physiology

Question 1

What is calcium required for?

Answer 1

Cardiac muscle action potentials and as a 2nd messenger

Question 2

Describe 2 forms of calcium

Answer 2

Diffusible and non diffusible

Question 3

Name 3 substances which maintain calcium homeostasis.

Answer 3

1. parathyroid hormone
2. calcitonin
3. vitamin D

Question 4

How does parathyroid hormone maintain calcium levels?

Answer 4

It increases calcium by resorption of bone by osteoclasts.

Question 5

How does calcitonin maintain calcium levels?

Answer 5

Reduces calcium levels by increasing bone formation by osteoblasts.

Question 6

Give a more detailed description of the role of osteoblasts.

Answer 6

Synthesise and secrete collagen fibres mineralised by calcium salts.

Question 7

What is hypercalcaemia?

Answer 7

Raised Ca2+

Question 8

What is hypocalcaemia?

Answer 8

lowered Ca2+

Question 9

What are the causes and results of hypocalcaemic tetany?

Answer 9

decreased Ca2+ intake
excessive Ca2+ loss
increased nerve excitability (pins and needles, muscle spasms)

Question 10

What causes hypocalcaemia?

Answer 10

Hyperventilation due to alkalosis when too much CO2 is expired.

Question 11

What can hyperparathyroidism cause for bones?

Answer 11

Bone demineralisation since parathyroid hormone releases calcium into the blood.

Question 12

Describe the effect of hypoparathyroidism

Answer 12

Defective tooth mineralisation due to under secretion of parathyroid hormone leading to low blood calcium levels.

Question 13

Give the terms for 2 vitamin D deficiencies - 1 in children and 1 in adults.

Answer 13

Rickets (children)

Osteomalacia (adults) - bone softening

Question 14

Give 2 bone diseases

Answer 14

Osteoporosis - decreased bone mass and density

Osteopetrosis - increased bone mass and density (distinct roots in x-rays, mandible > maxilla)