written by: Vasanth•edited by: Paul Arnold•updated: 10/12/2011
Many of our body’s actions are initiated and regulated by an army of chemicals known as hormones. They are part of internal communication system that lets cells ‘talk’ to each other. This guide introduces you to some key hormones and their functions, and the importance and value of hormone tests.
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The endocrine system is a fascinating and intricate organization of glands that produce and secrete hormones into the bloodstream, affecting just about every cell and organ in the human body. These endocrine glands are our principal hormone producers and include the hypothalamus, pituitary (considered the master gland as it regulates the functions of many other organs and glands), thyroid, adrenals, and the reproductive glands. They are ductless glands that have a network of capillaries running through them which provides direct access to the bloodstream.
Hormones are chemical messengers that transfer key information from one collection of cells to another. And though there are many different types of hormones each type only affects specific cells, and generally they are effective in minor amounts. They are instrumental in regulating growth, development and mood, reproductive processes, metabolism and tissue functions. Specific examples include epinephrine which increases heart rate, constricts blood vessels and opens air passageways; oxytocin which stimulates the production of breast milk and increases uterine contractions; and glucagon which regulates the release of glucose into the bloodstream.
As hormones are released into the blood they are able to carry out their actions and effects at some distance from the gland where they were made. Some hormones have long-term effects, for example those that control puberty and others have fleeting and short terms effects.
An understanding of the interactions between chemical messengers and their target cells is essential for getting to grips with how the endocrine system works.
Hormones are intricately involved in much of how well our bodies perform, and they keep us fighting fit and in tip-top shape. Too much or too little of a specific hormone can lead to illness. Monitoring their levels and other metrics can not only identify specific problems with the endocrine system, but also diagnose other conditions and potentially problematic issues.
This section puts a few of those tests under the microscope, exploring what's involved, why the tests might be ordered, the preparation that is necessary, the conditions they can check for and what they might reveal. For example a cortisol blood test checks out the levels of cortisol in the blood, abnormal levels of which might indicate conditions like Addison's disease and Cushing's syndrome.
Male and female hormones are classed as androgens and estrogens. They are both present in males and female, though at vastly differing levels. Estrogens are primarily produced by the ovaries and promote the development of secondary sexual characteristics such as the development of breasts as well as regulating the functions of the menstrual cycle. Androgens are produced primarily by a male's testes and help to control male sexual development and physique which includes such characteristics as the growth and development of facial, body and pubic hair, and the deepening of the voice.
Tests for male and female hormones can reveal much about the health status of an individual. For example, checking prolactin levels can diagnose fertility issues in women and the cause of sexual dysfunction in men.
Scientific research into hormones not only tells us more about the synthesis, development and functions of these chemical messengers, but also how we can adapt and use this knowledge for medical good. Human growth hormone is one of the most obvious examples, and it has been used to treat Turner Syndrome, Prader-Willi Syndrome, as well as a host of other applications. In addition, genetic engineering may become a viable way of increasing the number of insulin producing cells in people with diabetes.