Calcium Regulation

Question 1

Where is almost all the calcium stored in the body?

Answer 1

Bones

Question 2

What type of calcium is biologically active?

Answer 2

Unbound, extracellular calcium

Question 3

What hormones increase the amount of calcium

Answer 3

Parathyroid hormone (PTH) released by parathyroid gland and vitamin D - Actions of the kidney, bone and gut

Question 4

What hormones decrease the amount of calcium

Answer 4

Calcitonin released by the thyroid parafollicular cells

Question 5

How many types of vitamin D are there?

Answer 5

Two vitamin D2 (ergocalciferol) from diet and D3 (cholecalciferol) from ultraviolet life

Question 6

Where and how does the vitamin D2 and D3 become active? What is the name of the active form of calcium?

Answer 6

Precursor enters the bloodstream
The liver first hydroxylation
the kidney the hydroxylates it again
Forms 1,25 dihydroxycholecaliferol
A.K.A forms Calcitriol ACTIVE FORM

Question 7

How is Calcitiol regulated?

Answer 7

It is part of a negative feedback loop and therefore inhibits the enzyme which makes it in the kidney.

Question 8

How does the active Calcitriol work?

Answer 8

It promotes calcium re-absorption in the gut and the kidney; while promoting bone resorption which releases the calcium by breaking down bone.

Encourages the the reabsorption of phosphate in the kidney and the gut to enter the bloodstream

Question 9

What cells control and release calcium in the parathyroid gland?

Answer 9

Chief cells

Question 10

What does Parathyroid hormone do?

Answer 10

Increases the reabsorption of calcium in kidney, promotes bone resorption and also increases the synthesis of Calcitriol (i.e. active vitamin D)

Question 11

what do osteoblasts and osteoclasts do?

Answer 11

Build bone (OsteoBlast) and (OsteoClasts) consume bone