Chemical Coordination and Regulation Question 28
28. The blood calcium level is lowered by the deficiency of
[2008]
(a) parathormone
(b) thyroxine
(c) both calcitonin and parathormone
(d) calcitonin
Show Answer
Answer : a
Hints & Solutions
(a) A peptide hormone secreted by the parathyroid gland in response to low levels of calcium in the blood. It acts to maintain normal blood levels of calcium by increasing the number of osteoclasts, which break down the bone matrix and release calcium into the blood. It also increases the reabsorption of calcium and magnesium ions in the kidney tubules, so that their concentration is maintained in the blood.
