Nightingale Physiology Practice Test

The signaling from the pituitary that targets another gland to drive its hormone production is the thyroid-stimulating hormone. When TSH binds to receptors on thyroid follicular cells, it triggers a cascade that increases the synthesis of thyroid proteins and enzymes, enhances iodine uptake, and promotes the production and release of thyroid hormones T3 and T4. This is why TSH is the specific driver of thyroid hormone production. The thyroid hormones then exert negative feedback on the hypothalamus and pituitary to modulate TSH levels. Other pituitary hormones listed act on different glands—ACTH on the adrenal cortex, growth hormone on various tissues, and FSH on the gonads—so they don’t directly stimulate the thyroid.