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Thyroxine is a hormone controlled by negative feedback - OCR Gateway - GCSE Biology - Question 15 - 2019 - Paper 3
Question 15
Thyroxine is a hormone controlled by negative feedback. hypothalamus TRH anterior pituitary TSH thyroid gland thyroxine target cells throughout body There is... show full transcript
Worked Solution & Example Answer:Thyroxine is a hormone controlled by negative feedback - OCR Gateway - GCSE Biology - Question 15 - 2019 - Paper 3
Step 1
Once the cells of the body have the required amount of energy what will happen to the levels of the three hormones in the blood?
Answer
In response to an increase in metabolic rate, the levels of TRH (Thyrotropin-Releasing Hormone) and TSH (Thyroid-Stimulating Hormone) initially rise to stimulate the production of thyroxine. However, once the cells meet their energy needs, negative feedback mechanisms will trigger a decrease in TRH and TSH levels, leading to a decrease in thyroxine production as well. Thus, the correct conclusion is that all three hormones (TRH, TSH, and thyroxine) will decrease.