| The thyroid is a gland located on the anterior (front) | | | | (fats), in which the lipids are broken down into simpler |
| portion of the neck attached to the upper part of the | | | | or usable forms. The thyroid also promotes normal |
| trachea (windpipe). The thyroid is a bi-lobed gland. This | | | | heart function, normal neural development in fetus and |
| gland is small in size, about 4 centimeters long and 1-2 | | | | growing infants, and normal neural function in adults. |
| centimeters wide. | | | | The thyroid is influenced by hormones produced by |
| The thyroid produces and secretes biologically | | | | the pituitary gland and the hypothalamus. The pituitary |
| important hormones. Tissue in the thyroid is made up | | | | gland is located at the base of the brain. This gland |
| of two different kinds of cells: follicular and parafollicular | | | | produces thyroid stimulating hormone (TSH). TSH |
| cells. The thyroid is composed mostly of follicular cells | | | | stimulates the thyroid gland to absorb iodine and then |
| which secrete T3 and T4 hormones. The T4 hormone | | | | synthesize and release thyroid hormones. |
| (thyroxine) and T3 hormone (triiodothyronine) is derived | | | | The hypothalamus is located above the pituitary gland |
| from the amino acid tyrosine during iodination of the | | | | in the brain. This hormone produces thyrotropin |
| amino acid. Parafollicular cells secrete the hormone | | | | releasing hormone (TRH). The hypothalamus and |
| calcitonin. Iodine is important in the function of the | | | | pituitary gland detect low levels of thyroid hormones in |
| thyroid gland. Iodine is a chief component of the | | | | the blood. TRH is released by the hypothalamus to |
| hormones produced by the thyroid gland. Iodine | | | | stimulate the pituitary gland to release TSH. TSH in turn |
| deficiency can cause thyroid dysfunction, hence the | | | | stimulates the thyroid gland to produce more T3 and |
| need for iodized salt. The thyroid also produces and | | | | T4 hormones. This returns the thyroid hormone levels |
| secretes the hormone calcitonin. The hormone | | | | in the blood back to normal. |
| calcitonin decreases plasma calcium ions concentration | | | | Inflammation of the thyroid or a deficiency in iodine |
| by inhibiting the release of calcium ions from the bone. | | | | causes the condition called hypothyroidism. The thyroid |
| Calcitonin secretion is regulated by plasma calcium ion | | | | hormones become under secreted or are not |
| levels. | | | | secreted at all with hypothyroidism. Hypothyroidism |
| The thyroid plays a key role in regulating the body's | | | | symptoms include fatigue, slowed heart and |
| metabolism. What is metabolism? Metabolism is a | | | | respiratory rate, cold intolerance, and weight gain. |
| chemical reaction that occurs in the body's cells, | | | | Newborn infants with hypothyroidism (cretinism) are |
| releasing energy from the nutrients ingested. | | | | characterized by mental retardation and short stature. |
| Metabolism also uses energy to create other | | | | The thyroid can also be over stimulated in a condition |
| biologically important substances such as proteins. | | | | termed hyperthyroidism. This results in over secretion |
| Basal metabolic rate (BMR) is a measurement of the | | | | of the thyroid hormones. Symptoms associated with |
| body's required energy to keep functioning at rest | | | | this disorder include an increased metabolic rate, |
| (measured in calories). Exertion, stress, fear, and illness | | | | profuse sweating, heart palpitations, weight loss, |
| increase the body's metabolic rate. | | | | protruding eyes, and a feeling of excessive warmth. |
| The thyroid has many other bodily functions. The | | | | With both conditions the thyroid often enlarges resulting |
| thyroid helps regulate calcium levels in the body. The | | | | in goiter. However, goiter does not always indicate |
| thyroid can increase the body's temperature, thus | | | | disease. Thyroid enlargement can result during |
| burning more calories. This in turn increases the body's | | | | pregnancy and puberty. |
| appetite. The thyroid also promotes glucose | | | | If you exhibit some of the above symptoms, you |
| catabolism. Catabolism is the break down of complex | | | | should consult your physician for further follow up. |
| glucose forms into simpler, more usable forms for | | | | Many women due have serious concerns regarding |
| energy usage. This gland stimulates protein synthesis, | | | | their thyroid gland. If you have tried to lose weight with |
| increases lipolysis. Lipolysis is the hydrolysis of lipids | | | | no success, maybe it is due to the thyroid. |