The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing. It is referred to as the body’s ‘master gland’ because it controls the activity of most other hormone-secreting glands.
Where is my pituitary gland?
Computer artwork of a person’s head showing the left hemisphere of the brain inside. The highlighted area (centre) shows the pituitary gland attached to the bottom of the hypothalamus at the base of the brain.
The pituitary gland is a small gland that sits in the sella turcica (‘Turkish saddle’), a bony hollow in the base of the skull, underneath the brain and behind the bridge of the nose. The pituitary gland has two main lobes, the anterior pituitary gland and the posterior pituitary gland, which are joined by pars intermedia. The gland is attached to a part of the brain (the hypothalamus) that controls its activity. The anterior pituitary gland is connected to the brain by short blood vessels. The posterior pituitary gland forms part of the brain and secretes hormones directly into the bloodstream under the command of the brain.
What does my pituitary gland do?
The pituitary gland is called the ‘master gland’ as the hormones it produces control so many different processes in the body. It senses the body’s needs and sends signals to different organs and glands throughout the body to regulate their function and maintain an appropriate environment. It secretes a variety of hormones into the bloodstream which act as messengers to transmit information from the pituitary gland to distant cells, regulating their activity. For example, the pituitary gland produces prolactin, which acts on the mammary glands in the breasts to induce milk production. The pituitary gland also secretes hormones that act on the adrenal glands, thyroid gland, ovaries and testes, which in turn produce other hormones. Through secretion of its hormones, the pituitary gland controls metabolism, growth, sexual maturation, reproduction, blood pressure and many other vital physical functions and processes.
What hormones does my pituitary gland produce?
Regulated by releasing or inhibitory signals from the hypothalamus and the circulatory hormone level, the anterior pituitary gland produces the following hormones and releases them into the bloodstream:
- Adrenocorticotropic hormone, which stimulates the adrenal glands to secrete steroid hormones, principally cortisol
- Growth hormone, which regulates growth, metabolism and body composition via acting on the liver, bones, adipose tissue (fat deposit) and muscle
- Luteinising hormone and follicle stimulating hormone, also known as gonadotrophins. They act on the ovaries or testes to stimulate sex hormone production, and egg and sperm maturity
- Prolactin, which stimulates milk production in the mammary glands
- Thyroid stimulating hormone, which stimulates the thyroid gland to secrete thyroid hormones.
Each of these hormones is made by a separate type of cell within the pituitary gland, except for follicle stimulating hormone and luteinising hormone, which are made together by the same cell.
Two hormones are produced by the hypothalamus and then stored in the posterior pituitary gland before being secreted into the bloodstream. These are:
- Anti-diuretic hormone (also called vasopressin), which controls water balance and blood pressure
- Oxytocin, which stimulates uterine contractions during labour and milk secretion during breastfeeding.
Between the anterior pituitary and the posterior pituitary lies the pars intermedia, also called intermediate pituitary gland. Cells here produce:
- Melanocyte-stimulating hormone, which acts on cells in the skin to stimulate the production of melanin, which is a pigment that protects against ultraviolet (UV) radiation
What could go wrong with my pituitary gland?
The pituitary gland is an important gland in the body and the hormones it produces carry out varied tasks and regulate the function of many other organs. This means that the symptoms experienced when the pituitary gland stops working correctly can be different, depending on which hormone is affected.
Conditions that affect the pituitary gland directly can be divided into three main categories:
- Conditions that cause the pituitary gland to produce too much of one or more hormone(s). Examples include acromegaly, Cushing’s disease and prolactinoma.
- Conditions that cause the pituitary gland to produce too little of one or more hormone(s). Examples include adult-onset growth hormone deficiency, diabetes insipidus and hypopituitarism.
- Conditions that alter the size and/or shape of the pituitary gland. Examples include empty sella syndrome.
A cell type may divide and then form a small benign lump, known as a tumour, and the patient may then suffer from the effects of too much of the hormone the cell produces. If the tumour grows very large, even though still benign, it may squash the surrounding cells and stop them working (hypopituitarism), or push upwards and interfere with vision – a visual field defect. Very occasionally, the tumour may expand sideways and cause double vision as it affects the nerves that control eye movements. It should be emphasised that even when these tumours are large, they very rarely spread to other parts of the body. Lines of treatments to pituitary tumour include surgical operations and radiotherapy.