Question

Explain about the feedback mechanism of thyroid.

Answer 1

The secretion of thyroxine hormone by the thyroid gland is regulated by a self-controlling system called a negative feedback mechanism, which ensures its concentration remains within normal limits:

• When Thyroxine Levels Fall: A low concentration of thyroxine in the blood stimulates the hypothalamus and the anterior pituitary gland. The pituitary gland responds by releasing more Thyroid-Stimulating Hormone (TSH). TSH travels through the blood to the thyroid gland, stimulating it to produce and release more thyroxine, restoring the normal level.
• When Thyroxine Levels Rise: When the concentration of thyroxine rises above the optimal level in the blood, the high level acts as an inhibitory signal. It suppresses the hypothalamus and the anterior pituitary, reducing or stopping the secretion of TSH. Without TSH stimulation, the thyroid gland slows down thyroxine production, bringing the hormone level back to normal.