Final answer:
The anterior pituitary gland releases hormones into the hypophyseal portal system, which is a network of blood vessels that connects the hypothalamus and anterior pituitary, ensuring direct delivery of hypothalamic hormones to regulate the function of the anterior pituitary.
Step-by-step explanation:
The hormones of the anterior pituitary gland pass through blood vessels that are part of the hypophyseal portal system. Here is how the process works: The superior hypophyseal artery, emanating from the carotid arteries, delivers blood to the hypothalamus, where the hypothalamic hormones are released. These hormones travel through a primary capillary plexus into the portal veins that lead directly to the anterior pituitary. Upon reaching the anterior pituitary, these releasing or inhibiting hormones control the release of hormones synthesized by the anterior pituitary.
Then, the hormones produced by the anterior pituitary enter a secondary capillary plexus, from where they are drained into the systemic circulation. This portal system ensures that hypothalamic hormones reach the anterior pituitary quickly and in high concentrations without dilution in the systemic circulation.