Pituitary Gland what is it?

The pituitary gland is a pea-sized gland located at the base of the skull between the optic nerves. The pituitary gland secretes hormones. Hormones are chemicals that travel through our blood stream. The pituitary is sometimes referred to as the "master gland" as it controls hormone functions such as our temperature, thyroid activity, growth during childhood, urine production, testosterone production in males and ovulation and estrogen production in females. In effect the gland functions as our thermostat that controls all other glands that are responsible for hormone secretion. The gland is a critical part of our ability to respond to the environment most often without our knowledge. The pituitary gland actually functions as two separate compartments an anterior portion (adenohypohysis-hormone producing) and the posterior gland (neurohypophysis). The anterior gland actually is made of separate collection of individual cells that act as functional units (it is useful to consider them as individual factories) that are dedicated to produce a specific regulatory hormone messenger or factor. These factors are secreted in response to the outside environment and the internal bodily responses to this environment. These pituitary factors then travel through a rich blood work network into the blood stream and eventually reach their specific target gland. They then stimulate the target gland to produce the appropriate type and amount of hormone so the body can respond to the environment correctly. Similar to the cortisol factory there are additional factories: Growth Hormone Prolactin Gonadotropin ("sex hormones") Thyroid These five axes (factories) function as the anterior pituitary gland neuroendocrine unit. If any one of these factories become excited and start to overproduce their respective hormonal factor the net result is excess production of the final hormone product. So in the above example, if the cortisol cells (corticotrophs) lose their ability to respond to the normal stimuli from the environment and hypothalamus and develop their own independent, uncontrolled autonomous secretion they will produce more cortisol than the body requires. In return the adrenal gland will be over stimulated and secrete unregulated and unneeded catecholomines (stress chemicals). The net result is excess production of these important chemicals that raise the blood pressure and drive the heart in order to respond to stress when needed and can cause the body and internal organs to be stressed when there is no need. The consequences of overdriving the internal organs of the body can be life threatening. Often these cells that overproduce their respective hormone will clump together within a given area of the pituitary gland creating a true factory of over production – pituitary tumor. In addition to these five factories (cell lines) that produce hormones the anterior pituitary gland also contains remnants of the parent cells from which each of these individual cells came from. Specifically as the pituitary gland was formed the anterior gland contained a parent cell (pituicyte) which if you will was a parent cell. During embryological development this parent cells grew and matured into a series of daughter cells. Each of these daughter cells differentiated or learned to secrete a specific type of hormone eventually resulting in one of the five factory cells. In about 20% of the cases in fact the parent cell (which has not yet learned to secrete anything) grows excessively creating a collection or clump—pituitary tumor. This clump can grow and in the process create pressure on adjacent structures. Therefore these nonsecreting tumors create a problem for the patient not from excess hormone production but rather because of pressure on adjacent structures. What are the adjacent structures? If the pressure is exerted on the other members of the pituitary gland directly it impairs their ability to secrete their specific hormone – pituitary dysfunction. Among the most sensitive factories are the sex hormones (gonadotropins). If the pituitary tumor grows sideways (fat tumor) it will compress the cavernous sinus. This structure is an important cave located on either side of the gland that is continues a channel for blood to drain out of the brain, the carotid artery to supply the brain, and the cranial nerve that move the eyes. Fortunately, dysfunction of these critical structures is a rare and late event in most cases. However it is more likely that the gland will grow tall or upward (tall tumor). Often it will extend out of the bony structure that houses the pituitary gland (sella – named after the Turkish saddle). It will then grow through the thin "saran wrap" – like membrane (diaghrama) that separates the pituitary fossa or sella from the brain. It will then start to grow upward and start to push on the junction of the optic nerves where they cross (optic chiasm). When this happens the vision becomes compromised. The pattern of vision loss is a reflection of the compression at the site of crossing and so the patient develops blind spots along both temple regions. Both tumors that secrete hormones (functional tumors) and tumors that do not (non-functional tumors) can create this pressure or mass effect. More often it is these nonfunctional tumors that present with visual loss. In order for visual loss to occur the tumor has to be larger and grown through the confines of the sella and upward to the optic chiasm. These tumors are generally larger. The functional tumors often present when they are smaller because they have created a syndrome of excess production that prompts the patient to get help often before the vision is compressed.