When the product increases, the gland slows the release of the hormone. In some cases, hormone secretion slows the release of another hormone, thus regulating the release of that substance. The hypothalamus produces hormones that control the activities of the pituitary gland. Oxytocin causes uterine contractions during labor and stimulates milk release from mammary glands during nursing. It produces six different hormones.
Prolactin causes the mammary glands to produce milk after childbirth.
Thyroxin is usually secreted as T4, which is converted to T3, the active form. Iodine is a necessary component of thyroxin. Thyroxin increases metabolic rate and stimulates all organs to metabolize faster. Simple goiter is caused by insufficient iodine in the diet. TSH from the anterior pituitary overstimulates the thyroid, causing it to enlarge when iodine is absent.