Thyroid gland is an endocrine gland in the form of butterfly that locates in the neck below to Adam's apple. Thyroid blood include two lobes that are connected to each other through the thyroid isthmus. The tissue of thyroid gland consist of 2 types of the cells. The first one is essential for the production of two thyroid hormones known as T4( thyroxine) and  T3( T3). The release and production of thyroid gland hormones are regulated by hypothalamic-hypophyseal system.

Thyroid hormones stimulate the growth and development of the organism, increase the demand of the tissues in oxygen, increase systemic blood pressure, heart force and heart rate, body's temperature and level of basal metabolism. They improve mental and physical activity, enhance the speed of intellectual processes, increase lypolysis. Thyroid hormones increase the level of glucose in the blood, enhance gluconeogenesis in the liver, retards the synthesis of glycogen in the liver and skeletal muscles. In low doses thyroid hormones exert anabolic action while in higher concentrations exerts an expressed catabolic action on the protein metabolism.

 

Thyroid tissue is very vulnerable to many pathogenic factors that may cause different disorders in the thyroid gland. For example thyrotoxicosis or hyperthyroidism.  Thyrotoxicosis is a thyroid disease manifested in overproduction of thyroid hormones.  Thyrotoxicosis causes the following symptoms: weight loss, anxiety, agitation, increased irritability, mood changes, increased heart rate, blood pressure, polyruia, tremor and sweating. The main causes of thyrotoxicosis are toxic multinodular goitre, toxic thyroid adenoma and Graves' disease.

 

Another thyroid disease is hypothyroidism. This condition occur when thyroid gland does not produce enough thyroid hormones. is usually caused by the autoimmune thyroid diseases, decreased iodine consumption and thyroid tumors. Light severity level of the disease is manifested in muscles hypotonia, weight gain, consumption, bradycardia, weight gain, goiter, depression, cold intolerance, slow heart rate. In children hypothyroidism causes  cretinism. The treatment of  hypothyroidism includes hormonal replacement therapy.