Connective Tissue 4

Question 1

Function of parathyroid hormone

Answer 1

Parathyroid hormone (PTH) is released from the parathyroid glands when plasma calcium levels are too LOW.
Decreases the activity of osteoblasts and causes osteoblasts to secrete osteoclast-stimulating factor that stimulates the activity of osteoclasts
Thus, calcium is released to blood

PTH also acts on the kidneys to decrease loss of Ca2+ in the urine

Question 2

Function of Calcitonin

Answer 2

Calcitonin is released from the THYROID gland when plasma calcium levels are too HIGH.
Acts to inhibit the activity of osteoclasts and stimulate the activity of osteoblasts
Thus, stops bone resorption & more calcium salts are deposited in bone matrix