. Adventures with animals and plants. Biology. PROBLEM 6. Hormones Help Regulate Cell Activities 249. Goiter cases BMB 13-30 cases per 1000 \///////A 5-15 cases per 1000 I I 0-5 cases per 1000 Iodine in water parts per billion V/////XQ-2 parts per billion ] 2-20 parts per billion Fig. 241 Goiter ?nap of the United States showing co?iditio7is in 192^. Examine the figures just above. What conclusions can you draw about the cause of siynple goiter? Where were cases most commoji? Where were they least covmion? It may surprise you to learn that an enlarged thyroid gland may mean that the glan
. Adventures with animals and plants. Biology. PROBLEM 6. Hormones Help Regulate Cell Activities 249. Goiter cases BMB 13-30 cases per 1000 \///////A 5-15 cases per 1000 I I 0-5 cases per 1000 Iodine in water parts per billion V/////XQ-2 parts per billion ] 2-20 parts per billion Fig. 241 Goiter ?nap of the United States showing co?iditio7is in 192^. Examine the figures just above. What conclusions can you draw about the cause of siynple goiter? Where were cases most commoji? Where were they least covmion? It may surprise you to learn that an enlarged thyroid gland may mean that the gland is secreting too little thyroxin. You may have noticed that some people have a swelling in the neck in the region of the gland. They have a simple goiter. These goiters may occur when there is too little iodine in the diet. They are thus more common in regions where the amount of iodine salts in drinking water or in near-by farm products is too small. Health officers in such localities some- times add iodine salts to the drinkiuCT water. Sometimes the use of iodized table salt is recommended. A different type of goiter. In a very dif- ferent kind of enlarged gland or goiter the gland produces too much thyroxin. With oversecretion the rate of oxidation increases. The person is often restless and easily excited. In more severe cases, the patient loses weight, the temperature is above normal, and the heart beats more quickly than usual. This type of goiter {exophthalmic goiter) sometimes causes the eyes to bulge. It may become serious, unless the amount of thyroxin is reduced. This may be done by operat- ing to remove a portion of the gland or to shut off part of the blood supply to the gland. To test your understanding of the last paragraph do Exercise 2. An important discovery. There is a new and interesting treatment for overactivity of the thyroid gland. To understand it you must stop for a moment to examine an important discovery about atoms made in recent years. It has bee
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