Final answer:
Yes, the hypothalamus sends signals to the posterior pituitary gland to release the hormones it has produced, specifically oxytocin and vasopressin (ADH), into the circulatory system.
Step-by-step explanation:
The hypothalamus does indeed send signals to the posterior pituitary gland. This part of the brain produces two key hormones: oxytocin and vasopressin, or antidiuretic hormone (ADH), which are then transported to the posterior pituitary. These hormones are released into the circulatory system in response to neural signaling from the hypothalamus. While the posterior pituitary does not synthesize its own hormones, it plays a critical role in storing and secreting the hormones produced by the hypothalamus. Thus, when considering question 1, the answer is yes; the hypothalamus does send signals to the posterior pituitary.
Furthermore, this connection is facilitated by nerve axons that extend from the hypothalamus to the posterior lobe of the pituitary gland where these hormones are stored. Neurophysin proteins aid in the transport of these hormones from the hypothalamus to the posterior pituitary.