Thyroid Gland



Most vertebrates have two thyroid glands located on the neck. These two cloths fused together to form a single diaper. There is evidence that vertebrate thyroiditis evolved from the anterior sacs of the pharynx. These pouches probably served as channels in which the nutrients in the water flows through the mouth and out of the gills. The pouches that continue their development in vertebrates have lost all their connections with pharynx and become independent of the digestive system both structurally and functionally . This is just one example of a common evolutionary event iz the development of a new structure from an ancestral structure that is apparently irrelevant.
Years ago, a condition known as goitre, which caused the tyrosite to grow and swell and distort the neck was very common in the world, such as the Swiss Alps and the Great Lakes region of the United States. Goiter is often seen in connection with a number of other symptoms. These include: dry and swollen skin, hair loss, obesity, normal heart rate, physical laziness, and mental slowness. No reason for this was known. Then, in 1883, a Swiss surgeon, who believed that tyrosit had no important function, removed this diaper from some of his patients.
Most of these patients showed all signs of goiter, except for swelling of the neck. The results indicated that normal tyroside should be a chemical that inhibits these symptoms.
The oddity of patients with tyrocyte and overgrown tyroside showing the same symptoms could be explained by the secretion of the abnormal gland in goiter, despite the large size of the gland. Patients with goitre or other symptoms of hypothyroidism in the 1890s were successfully treated by injecting tyroside extracts or by adding small sheep tyroside fragments to their diet. However, nothing more specific to the hypothetic tyroside hormone itself was known. In 1896, a German chemist, E. Baumann, discovered that the tyrox does carry iodine, an element previously unknown in the body. But his discovery did not attract enough attention.
In 1905, David Marine, of Western Reserve University, realized that most people in Clevland were goiter. A high percentage of dogs were goiter. Marine, goitre food and water enough iodinewondered whether it was caused by lack of. When a small amount of iodine was added to the water of the experimental animals, goitre and other symptoms disappeared. Marine in 1916; He has tried this practice on about 2500 schoolchildren in Akron, Ohio. He gave the kids iodized salt. Another 2500 children who were used as controls were given iodine-free salt. After a period of time, only two goiter were found among the iodized salt children, whereas in 250 of the controls he had goiter. Although it took years to persuade a skeptical society, the use of iodized salt became widespread, and now hypothyroidism is rarely seen in the United States and Europe, due to iodine deficiency in soil and water.

A thyroid hormone is now known as thyroxine or T4, isolated in 1914 and synthesized in the laboratory in 1927, the need for iodine is better understood. This hormone proved to be an amino acid with four iodine atoms. Then, similar to thyroxine; however, another tyroside compound with only three iodine atoms was found.
This substance, called triiodothyronine or T3, is three to five times more active than thyroxine; but it is secreted in smaller amounts. They are usually considered together under the name “tyrocyte hormone dik or TH, since they actually show the same effects on the target cells. The most typical effect of TH is stimulation of oxidative metabolism in most tissues in the body. It is thought that the fat-soluble hormone passes directly through the cell graft and has a gene expression-modifying effect. Consequently, TH leads to an increase in the synthesis of certain enzymes, including respiratory enzymes in the mitochondria, and they increase the basal metabolic rate (BMR).
Hyperthyroidism - Excessive secretion of -TH - reveals a number of symptoms that you might expect: a body temperature above normal, excessive sweating, high blood pressure, weight loss, increased excitability and muscle weakness. This leads to a very typical symptom, which you may not be able to guess, because there is no clear connection to a metabolic rate higher than normal. This is the exophthalmia where the eyeballs are ejected. Although hypethyroidism can sometimes be controlled by antithyroid drugs, the more common treatment is the surgical removal of part of the gland or the partial destruction of radioactive iodine.
When hypothyroidism - hyperthyroidism is caused by the inability of the thyroid gland to work properly instead of iodine deficiency, thyroid hormone is treated. Failure to treat the disease causes serious problems, especially in newborns. These victims, which show abnormal development, are called cretin. They are similar to the dwarves and never reach sexual maturity. Their level of intelligence is very low and it is rare for them to exceed the four or five years of intelligence. The treatment of cretinism by giving hormones to infants with symptoms of deficiency is undoubtedly one of the achievements of modern medicine.


Although many symptoms of hypethyroidism - such as slow heart rate, obesity, physical weakness, and mental retardation - may be the results of low BMD, other symptoms, especially those seen in cretinism, cannot be easily explained in this way. One example is the very abnormal protein distribution in the body of cretins; there is an excessive amount of glycoprotein in their skin - this is why they appear - and there is an abnormally high protein concentration in the blood plasma. However, they have severe protein deficiency in their kidneys and livers and thus show significant growth retardation.
The administration of TH destroys all these symptoms. Thus, it is clear that TH plays an important role in the regulation of the synthesis and distribution of proteins. The effect of TH on protein metabolism is only a visible part of its overall role on many aspects of development. Without this hormone, most vertebrates cannot become normal adults and function. TH is not only necessary for the synthesis of normal growth proteins, but is also required for the testis and ovaries to reach functional maturity and contributes synergistically to the growth hormone secreted by the pituitary gland and contributes to skeletal development. In many downward organization vertebrates, TH is also required for metamorphosis and skin exchange.
In 1961, another thyroid hormone, calcitonin, was discovered. The function of this is irrelevant to TH, and its most fundamental effect is to prevent excessive calcium concentration in the blood. Calcitonin is carried out by separate glands (ultimobranchial glands) in the lower-organized vertebrates. In mammals, the corresponding tissue is fused with tyroside during embryonic development.
Source: poxox blogs
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