The graphic demonstrates the general hypothalamic-pituitary scheme, depicting the input of the central nervous system (CNS) to:
- Initiate the hypothalamus to stimulate the pituitary
- The pituitary then produces the trophic hormone, thyroid-stimulating hormone (TSH)
- TSH acts upon the thyroid (endocrine gland)
- The thyroid produces and secretes T4 and T3 to act upon the target tissues
Note the feedback of the secretory hormones to the pituitary and hypothalamus is either positive or negative, based on the circulating concentration.