Final answer:
The axon terminals in the hypothalamic-hypophyseal tracts store and secrete antidiuretic hormone (ADH/vasopressin) and oxytocin, which are released into the bloodstream affecting water balance and childbirth/lactation, respectively.
Step-by-step explanation:
The axon terminals of neurons of the hypothalamic-hypophyseal tracts store and secrete antidiuretic hormone (ADH), also known as vasopressin, and oxytocin in the capillaries of the inferior hypophyseal artery. These hormones are produced by the hypothalamus, specifically by the neurons in the paraventricular nuclei for oxytocin and the supraoptic nuclei for ADH. Upon receiving signals from these hypothalamic neurons, the hormones are released from the axon terminals into the bloodstream.
These hormones play important roles in the body. ADH helps control the balance of water in the body by signaling the kidneys to reabsorb more water, thereby reducing urine production, increasing blood volume, and regulating blood pressure. Oxytocin, on the other hand, plays a crucial role in childbirth and lactation, promoting uterine contractions during labor and milk ejection during breastfeeding.
It's also interesting to note that the hormones produced by the anterior pituitary are regulated by releasing and inhibiting hormones secreted by the hypothalamus, but these are not stored in the posterior pituitary like ADH and oxytocin. The transport of these hormones to and from the pituitary gland involves a network called the hypophyseal portal system.