Pituitary Gland

The pituitary gland is a small pea-sized protrusion from the base of the brain and sits on a bony pouch called the Turkish saddle (or sella turcica) on the sphenoid bone near the base of the brain. Also called the hypophysis, the pituitary gland is responsible for endocrine function from two major regions, an anterior and posterior, which secrete hormones regulating homeostasis and which act on other endocrine glands throughout the body. It is directly connected to the hypothalamus which is the main central nervous system (CNS) center and regulator. The hormones that the pituitary secretes help to regulate many body functions and an abnormality in this system can result in uncontrollable weight gain and lead to morbid obesity.

Posterior Pituitary

The posterior, or neurohypophysis, has a direct connection with the hypothalamus via a stalk that receives chemical messengers directly which gives rise to a tuberoinfundibular pathway. Hormones are made in the actual nerve cell body that are positioned in the hypothalamus which travel down to the posterior lobe which fire into the blood supply of the pituitary gland. The two main hormones secreted by the posterior pituitary are oxytocin and antidiuretic hormone (ADH), or vasopressin.

In women, oxytocin is released mainly after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating birth and breastfeeding. Oxytocin is released during orgasm in both sexes. In the brain, oxytocin is involved in social recognition and bonding. Antidiuretic hormones' (ADHs') main action is to conserve body water by reducing water loss in urine.

Anterior Pituitary

The anterior, or adenohypophysis, is also loosely connected with the hypothalamus via the hypophysial-portal blood vessels. This vascular connection allows signals to be transmitted and either stimulate or inhibit certain body functions. The anterior lobe is genuinely glandular and is a major component of the endocrine systems. The main hormones released by the anterior pituitary are human growth hormone (hGH), prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and endorphins.

The sum of the calculated release of these hormones are responsible for human growth, blood pressure regulation, in women for pregnancy and childbirth, breast milk production, sexual organ function, thyroid gland function, overall metabolism, and water regulation. If any of these mechanisms does not work properly, obesity and even excessive weight loss gain result. The pituitary regulates and controls cortisol production by the adrenal glands.

An overproduction can be caused by a tumor in the pituitary gland. When a pituitary tumor secretes too much adrenal cortical tropic hormone (ACTH), it simply causes the otherwise-normal adrenal glands to produce too much cortisol. This type of Cushing syndrome is termed Cushing disease and it is diagnosed like other endocrine disorders by measuring the appropriateness of hormone production. It is a disease that results from an increase in corticosteroid secretion from the adrenal gland and leads to obesity.