Calcium Homeostasis

Question 1

Calcium homeostasis refers to regulation of Ca ions in the ICF. True/False?

Answer 1

False

ECF

Question 2

What effect does hypocalcaemia have on voltage-activated Ca channels?

Answer 2

Opens them, causing hyperactive nerve and muscle conduction (hypocalcaemic tetany)

Question 3

In hypercalcaemia, calcium ions can combine with phosphate ions to form what?

Answer 3

Calcium phosphate (no shit) “stones” that deposit in blood and kidneys

Question 4

Which glands secrete the hormone responsible for controlling Ca concentration in the body?

Answer 4

Parathyroid glands

secrete PTH

Question 5

What effect does PTH have on the kidney with regards to Ca homeostasis?

Answer 5

Increases Ca reabsorption
Increases phosphate excretion
Stimulate release of calcitriol (vitamin D)

Question 6

What effect does PTH have on bone with regards to Ca homeostasis?

Answer 6

Increases Ca pumping into ECF

Increases bone resorption (activates osteoclasts)

Question 7

Which receptors on parathyroid cells are activated in hypocalcaemia?

Answer 7

CaSR (calcium-sensing-receptors)

Question 8

What effect does calcitriol (active vitamin D) have with regards to Ca homeostasis?

Answer 8

Increases Ca absorption in the gut

Question 9

Where is the hormone calcitonin produced from?What is its effect?

Answer 9

C cells of the thyroid (parafollicular cells)

Opposes effects of PTH