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The Pituitary

The pituitary gland is as large as the pea seed and is often called "the master gland". The pituitary regulates the entire endocrine system in humans.

In humans, the pituitary gland is one of the most vital glands in the endocrine system. It is located behind the nose-bridge and at the base of the brain. The pituitary stalk or the infundibulum attaches the pituitary gland to the hypothalamus. The hypothalamus regulates the hormonal secretion and inhibition of the pituitary gland. The master gland stimulates other glands and organs like the thyroid, adrenal, pancreas, ovaries, and testes that regulate body growth, metabolism, blood pressure, and sexual maturation. An unhealthy pituitary gland may lead to numerous metabolic disorders in humans. 

The Pituitary Gland Structure and Functions

The glands of the endocrine system secrete hormones in the bloodstream to reach their target cells, tissues, or organs. Hormones are chemical messengers that circulate in the bloodstream to their target cells or organs and carry out specific functions. 

Anatomy 

  • A fully developed and functional pituitary gland weighs roughly about 0.5 gms. 
  • The pituitary gland has distinct anterior (front) and posterior (back) lobes with distinguishing functions. The anterior pituitary is responsible for the secretion of all pituitary hormones after the stimulation from the hypothalamus. 
  • The posterior pituitary gland is not glandular and does not produce any hormones. It is made of neural tissue and consists of axons and axon terminals of the hypothalamic neural cells. It transmits the hormones originating from the hypothalamic neurons into the peripheral circulation (bloodstream).  
  • The pituitary gland is lined with capillaries and arteries for blood supply and hormone circulation. 

Functions of the Anterior Pituitary Lobe

The anterior lobe of the pituitary gland receives stimulation from the hypothalamus, whether to secrete or inhibit hormone production. Some hormones secreted by the anterior pituitary gland are:

  • Thyroid Stimulating Hormone (TSH) stimulates the thyroid gland to synthesise T3 (Triiodothyronine) and T4 (Thyroxine) hormones.
  • Growth Hormone (GH) secretion is crucial during the early years of body development in children. It helps in bone and muscle development. 
  • Sex Hormones like Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (LSH) maintain the normal functioning of the ovaries during the menstruation cycle and reproductive phase in females. They also regulate testosterone production in both males and females during puberty. 
  • Adrenocorticotrophic Hormone (ACTH) stimulates the adrenal glands to produce cortisol and androgens. These hormones are produced in response to stress that elevates your heartbeat, blood pressure, and glucose utility in the body. 

Functions of the Posterior Pituitary Lobe

  • The posterior lobe of the pituitary gland transmits the chemical messengers from the neurons in the hypothalamic region. It stores the hormones until stimulated for release.
  • Oxytocin secretion during pregnancy helps in vigorous uterine contractions during labour. Along with prolactin, it also affects breast milk production and flow. 
  • Antidiuretic Hormone (ADH), also called Vasopressin, regulates the water and sodium level in the blood and kidneys.  
  • Corticotropin-Releasing hormone is produced by the hypothalamus in response to stressful situations. It impacts the brain areas that control the digestive system, appetite, anxiety and improves the response to stress. 

Problems associated with the Pituitary Gland

There are numerous conditions associated with pituitary malfunction. The disorders could be due to abnormal levels of hormone secretion or due to the growth of mass lesions. 

  • The noncancerous tumours in the pituitary gland trigger the overproduction of hormones. The abnormally high amount of growth hormone, cortisol, sex hormones, and more drastically impact body metabolism. The overactive pituitary gland causes hyperpituitarism. 
  • In rare cases, radiation therapy, congenital causes, autoimmune diseases, and severe brain injury may alter the pituitary gland and fail to produce one or two hormones or synthesise a lesser amount in the body. Such a condition is called hypopituitarism. The lack of vital hormones affects the body’s metabolism and causes dwarfism, infertility, delayed puberty, thyroid malfunctioning, etc. 
  • Pituitary tumours can boost the production of prolactin hormone and cause prolactinoma. 
  • High levels of ACTH stimulate the production of cortisol that impacts major body organs and tissues.

Possible Treatment Plans

An endocrinologist will diagnose and provide appropriate treatment plans for the pituitary gland issues. 

  • In the case of tumours, radiation (X-rays) therapy can be used to treat benign tumours. 
  • Hormone therapy is used to reduce or increase the level of a particular hormone in the body. 
  • If the tumour is untreatable with radiation, surgery is performed to remove it. The surgical procedure is performed by the neurologist in consultation with the oncologist. The tumour is carefully removed through a nostril or via the cut on the upper lip. 
  • After complete recovery, regular check-ups are mandatory to avoid future complications and recurrence of the tumours. The doctor may prescribe oral medicines for a few weeks after the treatment. 

Conclusion

All the major body functions are monitored and regulated by the chemical messengers called the hormones that are secreted by the endocrine glands. The hormone production is controlled by the master gland called the pituitary, present in the brain. Pituitary malfunction can negatively affect the body’s growth and development, reproductive system, digestion, kidney functioning, mood, muscle mass, and vision. There are various treatment methods available that can treat the conditions associated with the pituitary gland. Learn more about the diverse range of study topics provided by Unacademy for better knowledge.