Hypothalamic–pituitary–gonadal axis in which the hypothalamus and pituitary direct neuroendocrine function. The hypothalamus is located in the brain and secretes GnRH. GnRH travels down the anterior portion of the pituitary via the hypophyseal portal system and binds to receptors on the secretory cells of the adenohypophysis. In response to GnRH stimulation these cells produce LH and FSH, which travel into the blood stream. These two hormones play an important role in communicating to the gonads. In females FSH and LH act primarily to activate the ovaries to produce estrogen and inhibin and to regulate the menstrual cycle and ovarian cycle. Estrogen forms
Sheehan's syndrome Sheehan's syndrome Sheehan's syndrome, also known as postpartum pituitary gland necrosis, is hypopituitarism (decreased functioning of the pituitary gland), caused by ischemic necrosis due to blood loss and hypovolemic shock during and after childbirth. The various signs and symptoms in Sheehan's syndrome are caused by damage to the pituitary, thereby causing a decrease in one or more hormones it normally secretes. Since the pituitary controls many glands in the endocrine system, partial or complete loss of a variety of functions may result. Most common initial symptoms of Sheehan's syndrome are agalactorrhea (absence of lactation) and/or difficulties with lactation. Many women