Abstract
The body has two main systems that are involved in the maintenance and reestablishment of homeostasis, nervous system and endocrine system. The endocrine system is made up of groups of organs that are involved in the production of chemical messengers known as hormones. Some of the major endocrine glands that are found in a human body include the hypothalamus, pituitary, thyroid, pancreas, pineal, gonad, adrenal, and pancreas glands. Although biological observations that are grounded in the functions of endocrine systems were noted by some of the ancient cultures, the modern understanding of various endocrine glands and the way they produce and secrete hormones evolved only in the past 300 years. Recent studies in the field of endocrinology have been focusing on the molecular mechanisms that are responsible for causing the effects of the hormones. Hashimoto's thyroiditis refers to an autoimmune disease where the thyroid gland is usually attacked by different types of antibody-mediated and cell-mediated immune activities. Most people with the disease do not show symptoms initially but enlargement of the thyroids become apparent as the disease progresses. Synthetic thyroid hormones, synthetic T4 and T3, are the ones used in treating Hashimoto’s disease.
The body has two main systems that are involved in the maintenance and reestablishment of homeostasis. One of these systems is the nervous system, which works by nerve impulses that are taken from one place in the body to another. The second system is known as the endocrine system and uses hormones to communicate. The endocrine system is made up of groups of organs that are involved in the production of chemical messengers known as hormones. The hormones are usually released into the blood and have an effect either on the organs that are near or far away from where they are produced. The hormones are classified in three main groups based on their chemical structures. The first group is the steroid hormones, which are those hormones steroid-like in shape and include prostaglandins and sex hormones. The second group is the amino acid derived hormones such as tyrosine. Third group is the peptide hormones, which makes the most diverse hormone group and include insulin (Carter, 2004).
Some of the major endocrine glands that are found in a human body include the hypothalamus, pituitary, thyroid, pancreas, pineal, gonad, adrenal, and pancreas glands. The hypothalamus is located in the brain and offers regulation to the pituitary gland’s secretory activity. Some of the hormones that are released by hypothalamus include growth hormone releasing hormones, thyroid-releasing hormone, corticotropin-releasing hormone, gonadotropin-releasing hormone, prolactin-inhibiting hormone and prolactin-releasing hormones (Seeley, Stephens, & Tate, 2004).
The pituitary gland is basically an extension of the hypothalamus. The pituitary gland is regarded as the master gland and works under regulation by the hypothalamus. Together with the hypothalamus, pituitary gland controls the various functions of the endocrine system. The pituitary gland secretes various hormones most of which are essential in female sexual activities such as pregnancy, menstrual cycle, birth and lactation. Some of the hormones secreted by the pituitary gland include growth hormones, thyroid-stimulating hormone, prolactin, luteinizing hormone and follicle-stimulating hormone.
The thyroid gland releases hormones that are responsible in regulating metabolism with an aim of regulating body weight and temperature. These hormones contain iodine and thus the availability of iodine is important in the manufacturing of thyroid hormones. The two hormones that are produced by thyroid gland are triiodothyronine or T3 and tetraiodothyronine or T4. Lack of iodine may result in thyroid hormone deficiency may result in the enlargement of the thyroid hormone, and this may result into a disorder called goiter.
The pancreas is the organ that secretes enzymes that are involved in digestion in the small intestine, and also hormones that are involved in the regulation of blood sugar. The hormones are secreted by the islets of Langerhans and are insulin and glucagon. The insulin removes excess glucose from the blood into the cells while glucagon increased glucose level in the blood. Lack of proper glucose regulation may result in diseases such as diabetes mellitus (Carter, 2004).
The other glands that are a part of the endocrine system are the adrenal glands. The adrenal glands sit above the kidneys and consist of two parts, the inner medulla and the outer cortex. The medulla is involved in the secretion of epinephrine or adrenaline and other hormones that respond to stress. The cortex is involved in the secretion of corticosteroids like cortisone. Corticosteroids work as anti-inflammatory and work by suppressing the immune system.
The gonads are the organs that are involved in producing gametes and in secretion of sex hormones. Sex hormone secretion is controlled by the hormones such as luteinizing hormone and follicle stimulating hormones that are secreted by the pituitary gland hormones. The testes secrete testosterone while ovaries secrete progesterone and estrogen. The female ovaries secrete the hormones such as FSH and LH (Clancy, 2007).
Although biological observations that are grounded in the functions of endocrine systems were noted by some of the ancient cultures, the modern understanding of various endocrine glands and the way they produce and secrete hormones evolved only in the past 300 years. The ancient people from Egypt and china noted difference in the men whose testicles were removed. The men who were castrated or eunuchs were noted to be less aggressive than those men who were not castrated. This behavior was not linked to castration until recently (JRank Science, 2013).
During the 17th and 18th centuries, some light was shed on the functions of the endocrine system with a few advances becoming significant in the development of understanding on the endocrine system. Thomas Wharton who lived between 1614 and 1673 and an English scientist noted differences between the ductless and ductile glands. Later in 1690s, a Dutch scientist called Fredrik Ruysch, who lived from 1638 to 1731, became the first person to state that thyroid glands secrete substances into the blood and have an important role in the body. It was a few decades later that Theophile Bordeu, who lived from 1722 to 1776, claimed that there were emanations that were given off by some parts of the body that had an influence on the functions of other parts of the body (JRank Science, 2013).
In 1849, A. A. Berthold conducted the greatest early experiment in endocrinology. In the experiment, Berthold used young male chickens. He castrated four of the chickens and two were left to have normal development and were later used as control samples for comparison. Out of the four chickens that were castrated, two of them were allowed to develop to maturity becoming chicken eunuchs. For the other two castrated chickens, Berthold transplanted the testes somewhere far from where the testes were originally. The results from this study were that those chickens that were castrated never matured into adult roosters while the chickens that received transplant grew into normal adult roosters. This experiment brought a big change in the field of endocrinology as it revealed the fact that hormones were able to access the blood from any site and the results for these hormones are not different from those released from their original site.
In the same year when Berthold published the findings, his findings, a British scientist known as Thomas Addison released a report the endocrine diseases, later to be named Addison's disease (AD). The patients with Addison’s disease had weak heartbeats, a gray complexion with a skin that looked sick and insufficient levels of hemoglobin in the blood. When an autopsy was done, each Addison’s disease patients studied had diseased adrenal glands.
Another scientist who made a contribution to the field of endocrinology is Claude Bernard, who lived between 1813 and 1878. Bernard, one of the famous French doctors of physiology made an observation that the endocrine system was involved in the regulation of the internal functioning of an animal. Bernard stated that some parts of the body made internal secretions, which were later taken to a distant target cells through the bloodstream. Bernard mainly worked on how the pancreas functions (McFarland & Schneider, 2009).
In 1889, Joseph von Mering together with Oskar Minkowski observed that removal of the pancreas resulted into an increase in the level of sugar in the blood, followed by coma and finally death. In 1922, Banting together with Best realized that when the pancreas was homogenized, and the derived extract injected in patients whose pancreas was removed it was possible to revert the condition (Macleod, 1989). By this time, the hormone that was responsible in reducing the sugar levels in the blood insulin was not discovered until in 1953 when Frederick Sanger sequenced it. Otto Loewi identified the neurohormones in 1921.
Recent studies in the field of endocrinology have been focusing on the molecular mechanisms that are responsible for causing the effects of the hormones. Earl Sutherland is one of the scientists who have studied these molecular mechanisms. In 1962, Sutherland made an investigation on whether the hormones entered into the cells or stayed outside to evoke their effects. He accomplished this by studying norepinephrine, and he noted that the receptors of epinephrine were on the target cells and not in the cells. Sutherland later identified the cyclic AMP compound resulting to the second-messenger-mediated pathway concept (European Journal of Endocrinology, 2011).
Hashimoto's thyroiditis refers to an autoimmune disease where the thyroid gland is usually attacked by different types of antibody-mediated and cell-mediated immune activities. The disease is an autoimmune disorder where the immune systems attack its own cells and tissues. The immune systems make different antibodies that are involved in attacking thyroid cells. The attack interferes with the production ability to make thyroid hormones of the thyroid gland. Hashimoto’s thyroiditis was the first autoimmune disease to be recognized. The disease was described initially by Hakaru Hashimoto in 1912, in Germany (Shomon, 2011).
Most people with the disease do not show symptoms initially but enlargement of the thyroids become apparent as the disease progresses. The gland is enlarged and results in the appearance of goiter. When the thyroid gland is damaged, it shrinks, and the goiter disappears. Some people who have Hashimoto’s disease do not develop hypothyroidism and those who do, there is mild or no symptoms that are associated with the hypothyroidism. Some of the common symptoms that are associated with hypothyroidism include fatigue, cold intolerance, weight gain, constipation, dry hair, depression, low heart rate and heavy menstrual periods (Shomon, 2011).
Hiroshimoto’s disease is usually treated depending on whether the thyroid is damaged to extent of causing hypothyroidism. When there is no hypothyroidism, the treatment targets reducing the size of the goiter while in some cases, the disease is not treated, and the disease progression is monitored. Synthetic thyroid hormones are the ones that are used in treating Hashimoto’s disease. Some of the synthetic hormones include synthetic T4 like the Synthroid or the synthetic T3. Synthetic T4 is usually preferred that the synthetic T3 since T4 stays in the body for a longer time than T3 hormone. The exact that is used while administering the synthetic thyroid hormone in most cases depends on the age and weight of the patient, as well as hypothyroidism severity. The patients constantly go through some blood tests to patients taking the hormones and may make adjustments as it is seen necessary. In some cases, the normal and healthy condition of the thyroid and the metabolic state may be restored after using the synthetic hormones (Waltofsky, 2012).
Since Hashimoto's disease is an autoimmune disease and trends in families has been reported, scientists are working on the identification of the genes that are responsible for causing the disease. Other factors such as the environmental influences are also being studied (Waltofsky, 2012). It is thus not possible to prevent the condition with the current available techniques but possibly in the future through gene therapy and identification of the gene possible Hashimoto’s disease may be diagnosed early enough and the condition rectified.
Reference List
Carter, J. S. (2004). Endocrine System. Retrieved August 21, 2013, from http://biology.clc.uc.edu/courses/bio105/endocrin.htm
Clancy, L. (2007). Reproductive system. Retrieved August 26, 2013, from http://studentreader.com/sex-organs/
European Journal of Endocrinology. (2011). History of Western Endocrinology. Retrieved August 26, 2013, from http://ej-endocrinology.org/history.html
JRank Science. (2013). Endocrine System - History Of Endocrinology. Retrieved August 26, 2013, from http://science.jrank.org/pages/2469/Endocrine-System-History-endocrinology.html
Macleod, J. J. (1989). JJR Macleod and the Discovery of Insulin. Journal of Experimental Physiology, 74, 87-96.
McFarland, J., & Schneider, C. (2009). Endocrine System. Retrieved August 26, 2013, from www.curtis1.com/curtis/assignments//Endocrine%20System.ppt
Seeley, R., Stephens, T. D., & Tate, P. (2004). Anatomy and Physiology (6th ed.). New York: The McGraw Hill Companies.
Shomon, M. (2011). Hashimoto's vs. Hypothyroidism: What's the Difference? Retrieved August 26, 2013, from http://thyroid.about.com/cs/hypothyroidism/a/hashivshypo.htm
Waltofsky, L. (2012). Hashimoto's Disease. Retrieved August 26, 2013, from the National Institute of Diabetes and Digestive and Kidney Diseases: http://www.endocrine.niddk.nih.gov/pubs/hashimoto/
