The Hypothalamus and Pituitary Gland
What is the hypothalamus?
The hypothalamus is located at the base of the brain and is the predominant link between the nervous system and the endocrine system.
The hypothalamus plays a major role in the control of the endocrine system, as it helps to regulate many basic functions of the body such as temperature and water balance.
Many functions of the hypothalamus are carried out through the pituitary gland, another endocrine gland located just under the hypothalamus and joined to it by a stalk called the infundibulum.
What is the pituitary gland?
The pituitary gland is roughly 13mm in diameter and is made up of two lobes:
The anterior lobe (in the front)
The posterior lobe (in the back)
The pituitary gland releases hormones that control many other endocrine glands and is sometimes called the ‘master gland’. The pituitary gland regulates bodily functions such as growth and metabolism.
How does the hypothalamus control the pituitary gland?
Image: The Hypothalamus-Pituitary Complex image, Image by OpenStax College, Sourced Under a Creative Commons 4.0 License from Wiki Commons
The hypothalamus controls the release of hormones from the anterior and posterior pituitary gland through different methods.
The anterior pituitary is controlled hormonally, through the secretion of releasing factors (RF)
The posterior pituitary is controlled by nerves, i.e., nervous control.
The anterior pituitary is controlled by releasing factors from the hypothalamus, which travels from the hypothalamus to the anterior pituitary via the bloodstream.
The anterior pituitary is then stimulated to produce and release the corresponding hormone.
For example, thyroid stimulating hormone releasing factor (TSHRF) is released from the hypothalamus, which then travels in the bloodstream to the anterior pituitary where TSHRF stimulates the anterior pituitary gland to produce and release thyroid stimulating hormone (TSH).
The posterior pituitary is controlled by nervous stimulation from the hypothalamus.
Hormones are produced in the cell bodies of nerve cells located in the hypothalamus and travel down the axons of these specialised nerve cells to the posterior pituitary, where they are stored for release into the bloodstream.
The posterior pituitary does not produce its own hormones.
For example, nervous stimulation from the hypothalamus activates the release of oxytocin from the posterior pituitary gland.