Chemical Coordination and Regulation Question 8
8. Which of the following pairs of hormones are not antagonistic (having opposite effects) to each other?
[2016]
(a) Parathormone - Calcitonin
(b) Insulin - Glucagon
(c) Aldosterone - Atrial Natriuretic
(d) Relaxin Factor - Inhibin
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Answer : d
Hints & Solutions
(d) Calcitonin exerts its effects by interacting with target cells, primarily in bone and kidney. The actions of PTH and calcitonin are antagonistic on bone resorption but synergistic on decreasing the renal tubular reabsorption of phosphorus. Insulin and glucagon work synergistically to keep blood glucose concentrations normal. An elevated blood glucose concentration results in the secretion of insulin and glucose is transported into body cells. Aldosterone secretion may be inhibited by potassium depletion, inhibitors of the renin-angiotensin system, dopamine and atrial natriuretic factor. The latter appears to be an important physiological regulator of aldosterone secretion. ANF inhibits basal, $ACTH$, Angiotensin II and potassiumstimulated aldosterone production in vitro by a direct action on the adrenal gland. Inhibin is a hormone secreted by granulosa cells of the ovary which inhibit the secretion of FSH (Follicle Stimulating Hormone) whereas relaxin produced by ovary and placenta at the time of childbirth to softens the ligament in the pelvis and widens the cervix.
