Question

which of the following is an example of negative feedback inhibition?
multiple choice
oxytocin release stimulated by uterine contractions
thyrotropin - releasing hormone (trh) causes the anterior pituitary to release thyroid - stimulating hormone (tsh)
thyroid - stimulating hormone causing thyroid hormone release
growth hormone stimulating the release of insulin - like growth factors
thyroid hormone preventing the release of thyrotropin - releasing hormone

Explanation:

Negative feedback inhibition occurs when the end - product of a process inhibits the production of the substances involved in the earlier stages of that process.

• Oxytocin release stimulated by uterine contractions is a positive feedback mechanism (as the response reinforces the stimulus).
• Thyrotropin - releasing hormone (TRH) causing the anterior pituitary to release thyroid - stimulating hormone (TSH) is a normal hormonal signaling (not negative feedback inhibition at this stage).
• Thyroid - stimulating hormone causing thyroid hormone release is a normal hormonal signaling (not negative feedback inhibition at this stage).
• Growth hormone stimulating the release of insulin - like growth factors is a normal hormonal signaling (not negative feedback inhibition).
• Thyroid hormone preventing the release of thyrotropin - releasing hormone: When thyroid hormone levels are high, it acts on the hypothalamus (and anterior pituitary) to inhibit the release of thyrotropin - releasing hormone (and thyroid - stimulating hormone). This is a classic example of negative feedback inhibition as the end - product (thyroid hormone) inhibits the production of the hormone (TRH) that was involved in its own production pathway.

Answer:

Thyroid hormone preventing the release of thyrotropin - releasing hormone