Answer:
Negative feedback is a regulatory mechanism in which the output of a system inhibits or reduces the system's activity. In hormone signaling, negative feedback loops are essential for maintaining homeostasis and preventing excess hormone production.
An example of a negative feedback hormone pathway is the regulation of thyroid hormone levels in the blood. The hypothalamus, located in the brain, releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary gland to release thyroid-stimulating hormone (TSH). TSH then travels to the thyroid gland, where it stimulates the production and release of thyroid hormones, including thyroxine (T4) and triiodothyronine (T3).
When thyroid hormone levels in the blood are too high, they inhibit the release of TRH and TSH through negative feedback. This reduction in TRH and TSH production leads to a decrease in thyroid hormone production, which brings levels back to normal. Conversely, when thyroid hormone levels in the blood are too low, the lack of negative feedback increases TRH and TSH production, which stimulates the thyroid gland to produce more hormones. This negative feedback loop helps to maintain a stable level of thyroid hormone in the blood.