CBSE Class 10 Answered

Anatgonism is the opposite effect of two hormones on the same target site. Antagonistic hormones help to maintain homeostasis.

For example:

1.  Blood Sugar Level (Antagonistic hormones – glucagon and insulin)

The increase in blood sugar level stimulates the secretion of insulin so that the sugar level is maintained. If there is fall in the blood sugar level below normal, then it stimulates the secretion of glucagon. Glucagon stimulates the breakdown of glycogen to glucose and thus, the normal sugar level is maintained.

2. Maintenance of calcium ion concentration in blood.

Parathyroid hormone (PTH) secreted by the parathyroid glands increases the absorption of calcium in the small intestine and reabsorption by kidneys. It also stimulated the release of calcium ions from bones. This increases the concentration of calcium ions in blood.

Calcitonin (CT) secreted by the thyroid gland produces the opposite effect by inhibiting the breakdown of bone matrix and thus decreasing the concentration of calcium ions in blood.