Correct Answer: C
Explanation:
(c) Parathormone is a hormone secreted by parathyroid glands. Hyposecretion of parathormone lowers concentration of calcium ions in the blood and tissues due to excretion of calcium in urine. This increases the excitability of nerves and muscles, causing cramps and convulsions. Sustained contractions (tetany) of the muscles of larynx, face, hands and feet are produced. This disorder is known as parathyroid tetany. Hypersecretion of parathormone draws more calcium from the bones, resulting in their softening, bending and fracture. This condition is called osteoporosis.