The pituitary gland is anatomically divided in two parts: the anterior pituitary (or adenohypophysis) and the posterior pituitary (or neurohypophysis). The anterior pituitary contains 6 different endocrine cell types, which produce 6 different kinds of hormones:
- thyroid stimulating hormone (TSH)
- adenocorticotrope hormone (ACTH)
- growth hormone (GH)
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
- prolactin (PRL).
Specific releasing hormones from the hypothalamus regulate the release of these hormones. Neurons in the hypothalamus release their hormone into the capillary network of the median eminence. The releasing hormones are then transported to the anterior pituitary via the portal vessels, where they stimulate the specific endocrine cells to secrete their hormones. Antidiuretic hormone (ADH) or vasopressin is the most important hormone in the posterior pituitary. This hormone is directly released in the bloodstream by neurons originating from the supraoptic nucleus.
The two hormones released by the posterior pituitary are
Extra info: The anterior pituitary secretes TSH, GH, gonadotropin, ACTH and prolactin, whereas ADH and oxytocin are released by the posterior pituitary.
ACTH stimulates the release of
Extra info: The adrenocorticotrope hormone stimulates the adrenal cortex. The adrenal cortex produces steroid hormones: sex steroids, glucocorticoids and mineralocorticoids. ACTH stimulates predominantly cortisol production.
I. The portal blood in the adenohypophysis is oxygen-rich. II. FSH and LH are corticotropic hormones.
Extra info: The blood in the anterior pituitary arrives via the portal circulation. In the median eminence this blood has already delivered oxygen, and, thus, when it arrives at the anterior pituitary cells it is poor of oxygen. FSH and LH are gonadotropic hormones.