The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
The thyroid gland, the body's largest endocrine gland, is situated in the neck just below the thyroid cartilage and secretes hormones necessary for growth and proper metabolism. A deficiency or overabundance of the secreted hormones results in one of two endocrine disorders, hyperthyroidism and hypothyroidism.
Hyperthyroidism results from an excessive production of the thyroid hormone, thyroxine. Thyroxine production is dependent on a sufficient intake of iodine and on stimulation by thyroid-stimulating hormone (TSH) from the pituitary gland. Symptoms of hyperthyroidism include an increase metabolism, rapid pulse, weight-loss despite normal or increased appetite, irritability, and occasionally, an enlargement of the thyroid gland itself. Because the body's metabolism is increased, patients often feel warmer than those around them. An extreme overproduction of thyroid hormones leads to a dangerous condition called thyrotoxicosis.
The most common cause of hyperthyroidism is Graves' disease, an autoimmune disorder characterized by a chronic course of remissions and relapses. The condition is usually accompanied by a protrusion, or bulging, of the eyeballs (exophthalmos).
Patients with hyperthyroidism are treated with an anti-thyroid drug or radioactive iodine, which destroys some thyroid tissue and subsequently reduces hormone secretions.
Hypothyroidism occurs when the thyroid gland does not secrete enough thyroxine. Deficiencies can occur when there is insufficient iodine in the diet or a glandular malfunction. Hypothyroidism is a common disorder, with subtle symptoms that can progress for years before being recognized and treated. The condition is characterized by a low metabolism, sluggishness, weight gain, hair loss and dry skin. Patients are often colder than those around them. Treatment is by administration of thyroxine. In the past, a disease known as goiter resulted from the lack in thyroid hormone secretions, but the use of iodized salt has helped eliminate the disorder.