Calcium

Question 1

Actions of Parathyroid hormone (PTH)

Answer 1

Increase calcium:
- Increases renal tubular reabsorption of calcium
- Increases synthesis of active vitamin D in the kidney which increases bowel absorption of Ca2+

Decrease phosphate
- reduces renal absorption

Acts on osteoblasts to increase ca2+ in extracellular fluid

Osteoblasts signal to activate osteoclasts => bone resorption

Question 2

Actions of active form of Vitamin D

Answer 2

Increases plasma calcium + phosphate
- Increases renal tubular reabsorption and gut absorption of calcium
- Increases osteoclastic activity
- Increases renal phosphate reabsorption

Question 3

Where in the kidney is phosphate reabsorbed

Answer 3

in the proximal tubule

Question 4

What hormone is secreted by C cells (parafollicular cells) of thyroid?

Answer 4

Calcitonin

Question 5

Actions of calcitonin

Answer 5

Reduces Ca2+ by
- Inhibits osteoclast activity
- Inhibits renal tubular absorption of calcium

Question 6

What other hormones have an impact on calcium metabolism

Answer 6

calcitonin
thyroxine
growth hormone