The pituitary is a small endocrine gland (that is, one that produces hormones) located at the base of the brain near the root of the nose. It consists of two parts: the anterior pituitary, or adenohypophysis, and posterior pituitary, or neurohypophysis.
By producing specific hormones, the adenohypophysis regulates the function of other endocrine glands, including the thyroid, adrenal glands, testes and ovaries. The adenohypophysis also produces growth hormone (GH) and prolactin.
The neurohypophysis is really part of the brain. Its main job is to produce antidiuretic hormone, which is necessary for maintaining the correct water balance in the body.
The pituitary gland is connected to the hypothalamus (a region of the brain) through the pituitary stalk. It is through this pedicle that the brain regulates the function of the pituitary. In close proximity to the pituitary gland are the optic chiasm (where the nerves of the eyes intersect), the oculomotor nerves (which make our eyes move), and the carotid arteries, in their cerebral part.
The adenohypophysis produces the following hormones:
- Growth hormone (GH): regulates growth during childhood until sexual development is complete; it also plays a significant role in regulating protein and fat metabolism
- Adrenocorticotropic hormone (ACTH): regulates cortisol production (the cortisone produced in our body) by the adrenal glands; cortisol regulation is vital for survival; cortisol plays a very important role in brain function, our response to infections, and in overcoming diseases.
- Thyroid-stimulating hormone (TSH): regulates thyroid function; the hormones produced by the thyroid regulate the speed at which all bodily functions occur.
- Follicle-stimulating hormone (FSH): regulates the function of the ovary and testis
- Luteinising hormone (LH): regulates the function of the ovary and testis
- Prolactin (PRL): responsible for the manufacture of breast milk
The neurohypophysis produces the following hormones
- Antidiuretic hormone (ADH): regulates reabsorption of water by the kidney, thus saving water, which is an essential substance for our body.
- Oxytocin: responsible for uterine contractions
There are various types of diseases of the pituitary gland. They range from alterations in function (ie, excessive production of a hormone or defective production of one or more hormones), to inflammation (for example, autoimmune hypophysitis), and tumours (pituitary adenoma); the latter can sometimes cause alteration in pituitary function, producing excess hormone; at other times, the pituitary adenoma does not produce an excess of hormone, but, if large enough, it can affect the normal pituitary mechanically, by reducing the production of one or more hormones (hypopituitarism), or sometimes, due to a compression effect, it can impair vision (pressure on the optic chiasm), or result in diplopia (split vision, due to compression on the oculomotor nerves, which make the eyes move). It can also cause headaches or, albeit rarely, the discharge of cerebrospinal fluid (the liquid that envelops the brain) from the nose.